David's Astronomy Pages Clair Dome Observatory - Scoping, Design & Construction

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This page records the scoping, design, construction & commisioning of my new dome observatory in 2018
and it's subsequent maintainance & operation in 2019-2023, including incidents & fixes.

	The Clair Dome Observatory
	Scoping Phase (Dec 2017-Jan 2018)
	New Observatory Concept
	Justification and Aims for New Observatory
	Outline Plan
	Design Phase (Feb-Mar 2018)
	Key Project Decisions
	Project Timeline
	Potential Issues
	Electrical and Connectivity Requirements
	AllSky Laptop & Weather/Environmental Data
	Current Cabling
	Cabling Plans for New Observatory
	Computer Control
	Power Automation
	Dome Automation
	Telescope & Imaging Automation
	Final Plan
	Construction Phase (late Mar - Apr 2018)
	Demolishing Existing Shed Observatory
	Preparing New Observatory Site
	Dome Arrival
	Dome Preparation
	Dome Assembly
	Dome Roof Interior
	Dome Outfitting
	Commissioning Phase (May-Jun 2018)
	Observatory Commissioning
	First Light Image (M13)
	Issues & Fixes
	Ramp-Up Phase (Jul-Aug 2018)
	Ramp Up Phase
	Automated Operation Testing
	Later Observatory Fixes and Enhancements (Aug 2018-Jan 2019)
	Observatory Door Improvement (2018-08-06)
	Shutter Drive Unit Reinstallation (2018-08-22)
	New Dome Clamps (2018-10-03)
	Relay Protection - Hardware Based Closure of Dome in the event of cloud/rain (2019-01-12)
	Cleaning, maintainence stuff and operational incidents (Jul 2019 to 2023)
	Outside Cleaning and Tree Line Trimming (2019-09-03)
	Flooded Observatory Floor (2019-10-18)
	Detached Rubber Trim (2019-10-24)
	Cable Conduit Fixing for Dome Controller Leads (2019-11-17)
	Repair to Observatory Base Sealent (2019-11-18)
	Drainage Holes for Condensation Puddles (2019-11-18)
	Fix to Limit Bracket to increase reliability of Shutter Operations (2020-12-18)
	Replacement Home Magnet (2020-12-26)
	Shutter opening issue (2021-01-08)
	Shutter chain modifications (2021-01-15)
	Repair to Observatory Wall Seals (2021-11-08)
	Shutter failed to fully close, hold up on bottom aperature lip (2021-11-10)
	ASCOM Driver Review (2022-07-02)
	Home Magnet Tests (2022-07-13)
	Dome Cleaning (2022-11-04)
	Snow slid off Shutter onto Scope (2023-01-16)

The Clair Dome Observatory

This page records the scoping, design, construction & commisioning of my new dome observatory in 2018, and its susequent maintainance and operation (2019-2022). 

New Dome Observatory (Clair 3)

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Scoping Phase (Dec 2017 - Jan 2018)

New Observatory Concept (Dec 2017)

After using my roof-off roof observatory for some 21 years at 3 different sites and struggling badly with it during its two final seasons (2016-2017)  I decided that in early 2018 that I would replace it with a completely new observatory. The plan is to get a 2.2m dome observatory with rotation and shutter drives.   The observatory would be placed on either a square, octagonal or circular concrete pad, on pretty much the same site as the existing observatory.  Justification and aims for the new observatory are listed in a following section.

Photos below show the existing roll-off roof observatory together with two photoshopped views of how the new dome observatory might look.

Previous Roll-Off Roof Observatory		Mock-Up View of New Observatory		Alternate Mock-Up of New Observatory

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Justification and Aims for New Observatory (Jan 2018)

I had 3 main justifications/aims for the observatory :

1) Resolve 5 specific issues associated with the Clair 2 roll-off roof observatory:

 - difficulties in opening/closing current observatory roof
   (roof is increasingly difficult to move due to gradual warping of the two sides, causing wheels to fall off the wall rails)

 - safety issues associated with opening/closing 'stiff' roof (potential for back, shoulder or hamstring injury)

 - safety issue associated with deterioration (rot) in one of the roll-off support stands (potential for crush injuries if roof collapses)

 - buffetting of telescope by wind with consequential poor imaging in anything more than a light breeze
   (buffetting problems were magnified in 2009 when a new roof-off was built and a new larger scope (12" LX200) was installed
    this had the combined affect of exposing the telescope to more wind which has reduced the quality of certain data and
    reduced the number of nights when the scope can be operated)

 - gradual deterioration (rot) & water ingress in parts of the 21 year old shed frame

 2) Provide additional capability and opportunities from a new Clair 3 dome observatory:

  - increase astronomical observing/imaging time by being easier to operate and by being less sensitive to weather conditions

 - allow secondary scope & camera to remain attached to the main telescope between sessions making setup quicker and more reliable  
   (in previous roll-off roof observatory the secondary scope & camera has to be mounted, connected, disconnected & dismounted at each session)

 - reduce number and length of visits to the observatory by increasing remote operation capability (e.g. opening/closing roof remotely)

 - create opportunity to improve observatory electrics, wiring, cabling, communications and lighting

 - provide a robust weather resistant structure requiring less maintainence.

 - allow fully automated operations in due course (entire session run from a pretty much a single mouse click)

  3) Help meet specific future observing plans

 - exoplanet transits

  - high resolution planetary imaging

  - solar observing

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Outline Plan (Jan 2017)

The outline plan for the new Dome Observatory was for it to sit in approximately the same location as the existing Roll-Off Roof Observatory, but offset slightly to allow for a new pier base and to position it slightly further from boundary fencing to allow room for up to 2 bays.  The new observatory will reuse the existing armoured Power Cable  and use the existing Telescope and Camera equipment (12" LX200 /  80mm APO,  ST-10XME / ZWO ASI178MC)

The initial outline plan view of the new observatory is shown below. The precise offset from existing observatory, the precise southerly pier offset from dome centre, the pad size/shape and the positions of the observatory door and bay(s) will subject to later revision as design & planning progressed..

Initial Outline Plan for New Observatory

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Design Phase (Feb-Mar 2018)

Key Project Decisions (Feb-Mar 2018)

The key project decisions that were made during early 2018 were : :

• Observatory Size/Brand
• Dome Operation/Drives
• Number of Bays
• Observatory Base
• Pier Block
• Observatory Assembly
• Pier
• Pier Offset
• Pier Height

The decision made under each topic and the rationale is described below:

• Observatory Decison:  2.2m Full Height Dome Observatory from Pulsar Observatories
  
  Alternates Consided
  - other sizes
  - other suppliers
   
  Rationale
   - 2.2m size adequate for 12" scope
   - 2.2m size adequate for expected largely remote and unattended telescope operations
   - well regarded observatory maker based in mainland UK ( https://www.pulsarastro.com/ )
   
• Dome Drives Decision:  Rotation and Shutter Drives
   
  Alternates Considered
   - just rotation drive (no shutter drive)
   - entirely manual operation
  
  Rationale
   - Rotation and Shutter Drives needed for unattended and remote telescope operations
   - highly variable weather demands a means of being able to shut the observatory dome rapidly and without necessary going outside to do so.
   
• Number of Bays Decision:  Two bays
  
  Alternates Considered
   - just one bay
  - no bays
   
  Rationale
   - maximise clear floor space and obtain a clear segregation of  all-sky & weather monitoring
     from telescope/camera observing with the huge amount for cabling & adapters involved
     (both of these points will make provide a very welcome improvement on the current observatory)
   - bay 1 to house power panel and all sky/weather monitoring computer & supporting kit
   - bay 2 to house observatory computer & supporting kit
   
• Observatory Base Decision: Circular Concrete Pad
   
  Alternates Considered
   - rectangular or octagonal concrete pad
  -  wooden base
   
  Rationale
   - concrete provides a strong, resilient foundation
   - circular pad for circular dome considerd more aesthetically pleasing than a rectangular pad (though more difficult to construct)
   - circular pad smaller area should absorb less heat during daytime than a rectangular pad
    (circular pad should also require less concrete but was not a factor)
   
  Notes:
  Concrete pad thickness was 20cm thickness increasing to 25cm thickness where the ground elevation was lower. Pad thickness is greater than the minimum 15 cm written in Pulsar Observatories' guidelines due to the sloping nature of the site.
  In the centre the pad drops off to a 65 cm thickness to provide extra support for carrying the pier/telescope. A layer of gravel was placed below the concrete. 
   
• Pier Block Decision:  Integrated into Pad (instead of being isolated)
  
  Alternates Considered
  - Isolated Pier Block
   
  Rationale
   - The observatory is to be mainly used for unattended and remote operation and therefore vibration
     due to footsteps and movements in the observatory will generally not be an issue. 
  - Observatory will be securely bolted to the pad and hopefully there shouldn't be too much wind induced
    vibration at the wind speeds the observatory will be used for observing.
  - It was the best way to obtain a good flat surface to the observatory base (given the non-rectangular nature of base)
  - The concrete pad will be more appealing / useful for other things to subsequent buyers of the property if it is without wooden isolating  dividers (though there will of course be the issue of the four metal pier studs sticking out of the concrete !)
   
  Notes:
  Hole was dug in the centre of the base to to provide a pier block with dimensions of 75 x 75 x 65 cm (width, length, depth) , with the orginal intention of isolating it from the surrounding pad which is the ideal situation. In the event it was found difficult to design and deliver a method of both isolating the pier block and ensuring that it was perfectly level with the surrounding pad, given the circular form work needed for the pad.  Dimensions of pier block are smaller than those suggested in Pulsar Observatories Guidelines for building the observatory base.   A smaller size was used as it was considered adequate given the experience of previous concrete pier on the same site.  The centre was offset to the south slightly to reflect the designed offset for the pier  (6 cm). There is potential risk of joints forming later in the concrete along the lines where thickness of the pad changes from 20 to 65cm. (this will be monitored by lifting the rubber mats from time to time)
   
• Assembly Decision:  Self-Assembly
  
  Alternatives Considered
  - Assembly by Observatory Supplier (Pulsar Observatories)
   
  Rationale
   - It was a means to saving a little money (or at least offsetting the cost of a second bay)
  - The observatory will need be disassembed and re-erected as part of a future house relocation
    so it was felt reasonable to gain maximise experience now.
  - It simplifed the project timeline by disassociating completion of the concrete base from
    delivery of the dome and enables erection of the dome to be done in good calm weather
    (difficult to pre-arrange in Scotland).
   
• Pier Decision:   Existing Metal Pier, but shortened
   
  Alternatives Considered
  - new Pier from Pulsar Observatories or other supplier
  - new custom pier
   
  Rationale
  - It allows me to use my existing top plate which fits my Meade Ultra-Wedge
  - Existing pier is still perfectly functional but needs rust to be removed and
    to be shortened for the new observatory   (it will now sit on the observatory floor itself
   whilst previously it was attached to a pier block  that lay some 20cm below the observatory floor)
  
  Notes:
  It was originally hoped that reusing my existing pier would save on cost. but this is unlikely to be significant gives the cost of shortening the pier by a blacksmith/fabricator.
   
• Pier Offset Decision:  6.5cm to south
   
  Alternatives Considered
  - pier offset 3.5cm to south
  - pier centered (no offset to south or north)
   
  Rationale
  - For my 12" LX200 sitting on Meade Ultra-Wedge at my Scottish latitude the functional centre
    of the scope (intersection of RA and declination axes) overhanges the centre of my pier by 3.5cm. 
    Thus a 3.5cm pier offset to the south is the natural offset to be used.
   
  - An additional 3cm offset was applied to reduce the region near zenith where guidescope/secondary
    scope would be oculuded by the dome roof (a larger offset would provide even more sky to
    guidescope but would then compromising the ability of main scope to see zenith or begin to increase
    the minimim altitude that can be viewed and further educe the length of dewshield that can be used)
   
  - The additional 3cm offset also allows some additional workspace at the back of the telescope for
    manipulating and change out of camera and other equipment (more of issue with circular dome
    observatory with its inward curving roof than my previous square shed observatory ?)
   
  Notes:
  The 6.5cm pier offset positions the centre of the scope 3cm south of the centre of the dome.  This should allow guidescope to operate up to altitude of 80 deg, instead of up to only 75 deg.  Any further offset reduces the ability of main scope to view zenith (altitude 90 deg). Telescope overhang at a potential future site in Southern England would be 9cm instead of 3.5cm, this can be dealt with when re-building/re-erecting dome at that future site and doesn't impact the current decision.
   
• Pier Height, total including top plate :   96.3cm
   
  Alternatives Considered
   - a shorter pier
   - a taller pier
   
  Rationale
  - 96.3cm height enables scope to still sit reasonably low in observatory for added protected
   and for running a short dew shield  ( a more elevated scope provides the scope with slightly
   less protection and reduces the length of dewshield that can be run)
   
  - 96.3cm height still enables me to see down to 5 deg altitude with the main scope (down to 0 deg with secondary scope)
   (a less elevated scope increases the minimum altitude that can be viewed)
   
  - Provides an reasonable compromise in telescope height between current observatory
    location (57.3 deg N) and a potential future site in S.England (50.7 degN) 
  
  Notes:
  A considerable amount of investigation went into selecting pier height including using dome sizes shown in Pulsar's 2.2m Dome Technical Drawing,  measurements of the scope and wedge, and the building of an integrated Excel Worksheet with Charts to examine the impact of different configurations and the impact on operation of the scope. This work considered not only my current latitude in NE Scotland but also that at a potential future site in Southern England. The difference in latitude (50.7 deg N instead of 57.3 deg N) would causes the telescope at a potential new site to sit 4 cm lower in the observatory on the same pier due to the less elevated positionof northern Celestrial Pole.  Notionally this requires the pier that is 4cm taller than the one used in Scotland in order to operate the telescope at the same height.
   
  Given that I would perfer to re-use my current pier at a new site and after shorterning the scope now I would clearly prefer not to have to lengthen the pier later.  Fixing bolts for my Top Plate allows me to make a 1.3cm difference to the overall height of the pier.   I can have the Top Plate at its lowest setting here in Scotland and then raise it by 1.5cm when operating the pier at a potential future site in Southern England, making just a 2.7cm difference in effective telescope height between the two sites which is manageable.

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Project Time Line (Mar 2018)

An outline project plan was maintained during the planning & construction phases.  An important part of the planning effort was the recognition of key dependancies between different decisions and tasks.

The actual time line for the completed project is shown below

Completed
- 2017-12-10  Project Conception "New Observatory in 2018" 
- 2018-01-10  Decide key dome specifications, 2.2m Full Height, 2 bays, White 
- 2018-02-18  Agreement to proceed
- 2018-02-19  Order 2.2m dome observatory & accessories from Pulsar Observatories
- 2018-03-26  Remove existing observatory (including removal of roll-off supports & metal pier, photos
- 2018-04-02  Dig hole for new pier base and footings for the observatory's concrete pad, photos
- 2018-04-03  Contract local concrete supplier to arrange delivery of 1.2-1.5 cu.m of concrete
- 2018-04-05  Construct and level circular former for concrete pad
- 2018-04-06  Recieve Volumetric-Mix Concrete, wheelbarrow concrete and pour into pad shuttering
- 2018-04-10  Deliver Pier to local metal fabricator/blacksmith to reduce its height
- 2018-04-10  Receive dome observatory, this came 7 weeks after order placement
- 2018-04-11  Survey north alignment and pier position
- 2018-04-11  Finalise required Pier Height Modification
- 2018-04-12  Consult electrician regarding power supply for new observatory
- 2018-04-10  Contract local metal fabricator/blacksmith to reduce the height of current metal pier
- 2018-04-19  Self install Dome Observatory (with help from son)
- 2018-04-21  Install & hook up power panel
- 2018-04-28  Drill holes in Concrete Pier Base, Install Bolts, 
- 2018-05-01  Recieve Shortened Pier from Fabricated/Blacksmith
- 2018-05-02  Install pier
- 2018-05-02  Install Telescope.

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Potential Issues identified prior to Project Start (Mar 2018)

6 potential issues were identified prior to start of the project

• Observatory Size
  The new observatory might not provide as much space as the former observatory
   
• Pier Block
  The old concrete pier block may cause physical problems during the construction of a new pier block
   
• GPS Fix
  The LX200 telescope may note be able to get GPS fix (including accurate time) in observatory at start up with TS80 Guidescope permanently attached and may hang
   
• Dome Aperture
  Main and/or secondary scope might not be able to see out through the Dome Aperture when pointing in particular directions, such as close to zenith
   
• Condensation
  Condenation might be a problem in the dome observatory with deterimental impact on equipment etc
   
• Power Overloading
  The power requirements including new equipment might exceed 13A fuse rating on the main plug serving the observatory

A further particular issue was identified during constuction/commissioning

• Door Size.
  The relatively small door on Pulsar Observatory makes it awkward/difficult to bring large/heavy items safely into and out of the observatory  
   (particularly the heavy/bulky Metal Pier and the heavy/bulky 12" LX200 Telescope)

 These potential issues and the work undertaken to address/solve them is discussed below:

1. Observatory Size.  Whilst the current and the planned new observatory are both predominantly used for automated or remote control imaging, the 2.2m dome observatory being circular and having sides that are shorter has less internal space for moving around in than my current square full-height roll-off observatory. This might become frustrating unless special care is taken over the interior design and layout of the observatory.  Hopefully setup time in the observatory will be shorter and the unplanned visits will be fewer in number.
   
   Proposed Solution
   - Include minimum of one bay to New Observatory for holding 'Power Panel', ''Ethernet Switch (Hub)', '
     AllSky Laptop' (including related USB Hub and adapters) + Miscellaneous Items for Storage
   - Carefully plan out the observatory cabling (240v power leads, 12v power leads, serial leads, USB leads, ethernet leads)
   - Carefully plan out positioning of work spaces for Observatory Control Laptop, AllSky Laptop and Miscellaneous Items
    
2. Existing Pier Block.  The existing concrete pier block(which can't easily be removed) may prevent or cause problems during the construction of a new concrete pier block (Note: an elevation difference to the concrete pad required for the new dome observatory, and a desire to move the observatory slightly further away from boundary fencing prevents reuse of existing pier base).  The new pier block may end up directly abutting the old pier block. Whilst this might help support the new pier, it may also lead to unplanned transfer of vibrations when walking or moving about on the concrete observatory floor which in part lies on the old pier block.
    
   Proposed Solution
   - Offset the New Observatory from the old observatory by a sufficient distance so that a new pier base can be dug without significant impact from the old concrete pier base. The new base will effectively sit alongside the old pier base (photo)
    
3. GPS Fix.  LX200 may not be able to get a GPS fix (including accurate time) at start up and may effectively 'hang' whilst it searches in vain for a gps fix.  Based on the occasions when the TS APO 80mm guidescope has been accidentally mounted before powering up the LX200 this will almost certainly be a problem when the guidescope is permanently left attached to the LX200 main scope between sessions in new observatory. The fibreglass dome itself may or may not hinder getting a gps fix.   Since the observatory is at a permanent site, not getting a gps fix at start-up is not a particular problem since site coords get are saved for the site in Autostar II. However getting a gps fix is a very convenient way to ensure that the LX200 operates during the session with an accurate date/time since date/time are not preserved through power down/power up cycles. Manually entering date/time is a big inconvenience. 
   
   Proposed Solution
   - Disable GPS On LX200 (done from Autostar II menu). Note this also disables the acquisition of Date/Time.
   - Change 'Auto Set Time' setting in LX200GPS/R Ascom Driver so that scope time is always set to computer time upon connect.
   - Change Start-Up procedure
       - Update Computer Time from Internet at the start of or just before start of the session
       - Turn on LX200 (GPS disabled)
       - Connect to LX200GPS/R via POTH-Hub & LX200GPS/R ASCOM driver (scope time set to computer time)
       - Check that Telescope's coordinates match those expected.
   
   (An alternative solution would be the purchase and installation of a GPS repeater, positioned so that its internal transmitter lay close to the GPS reciever in the LX200's left-hand fork arm)
    
   
4. Dome Aperture.   LX200 main scope and/or TS 80mm APO secondary scope might not be able to see out through the Dome Aperture when pointing in particular directionns.  Pointing at zenith or just beyond zenith is a particular problem as the shutter can only be pulled back some 15-20cm beyond zenith.
   
   Proposed Solution
   - Install Pier some 15-17 cm south of dome centre to enable 80mm scope to still see the sky when main scope is pointing near to zenith (with shutter open to the south), but still allows the main scope to see the sky when pointing beyond zenith (with shutter open to north).    This was later changed to just a 6.5cm offset as larger offset affected the ability of main scope view at zenith
   - Use POTH Hub to synchronise the pointing of the dome with that the main telescope. The algorithum is understood to take into account the position of the scope's RA/Dec Axes recorded in setting as well as the altitude and azimuth that the scope is pointing to.
    
5. Condensation. Condensation is reported to be a potential problem in Fiberglass Dome Observatories
    (even though exposure to dew and/or frost will be less than existing roll-off observatory)
    
   Proposed Solution
   - Monitor situation to see if condensation turns out to be a real problem or not.  
     (I personally think the humidity levels will be lower than the roll-off observatory -
   - If required,  purchase a de-humidifier to reduce humidity & prevent condensation
     (Humidifier will require the following features:   Desiccant dehumidifier,  Continuous drain facility , Humidistat)
    
6. Power Overloading.  Total observatory power requirements might exceed 13A fuse rating on the main plug serving the observatory due to the addition of extra equipment associated with the New Observatory (a) Rigel Dome Rotation Drive & Induction Charger for Shutter Drive, b) a Focuser for 80m APO scope  and c) a Dehumidifier) 
    
   Proposed Solution
   - Firstly understand if there is a problem here or not, by compiling list of all equipment to be used and the wattage and power amperage draw of each item at 240V equivalent, and finally by calculating the summed amperage draw (assuming all equipment ws being used simultaneously) and compare against the 13A limit.
   - Initial assessment indicates maximum observatory power consumption is 1728W (7.2A @ 240V),  excluding hairdryer & assuming a 50% power efficicieny on AC adapters, or 3328W (13.9A @ 240V) including hairdryer.
   - Hairdryer (1600W, 6.6A) is the single most power-hungery item of equipment in observatory and should only be used when other equipment isn't drawing high current (i.e. when telescope & dome is stationary and camera & focusers are paused). In event of problems dew heater should also be temporarily turned down or turned off whilst using the hairdryer.
   - Dehumidifier should be switched off during observing sessions to reduce power load
   - Follow up initial assessment with a more accurate assessment using a Power/Voltage/Amps/Watt Electricity Usage Monitor with Digital LCD Display (which can be easily purchased through Amazon for £16 or so)
   
   
   Another Issue / risk that surfaced during the project was :
   
7. Door Size. The relatively small door on Pulsar Observatory makes it awkward/difficult to bring large/heavy items safely into and out of the observatory (particularly the heavy/bulky Metal Pier and the heavy/bulky 12" LX200 Telescope)
   
   Proposed Solution
   - Built some form of platform on outside of observatory entrance and a smaller platform inside of the observatory entrance to allow the heavy 12" LX200 telescope to be more easily moved sideways through the observatory's doorway.

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Electrical and Connectivity Requirements

A study was conducted to look at the number of power sockets and number of ethernet, serial & usb connections. This was extended to look at the power requirments of the all equipment that was envisioned to be used in the new observatory.

			Power			Direct	Indirect
Set	Equipment		Sockets	Ethernet	Serial	USB	USB	Notes
Set 1	Observatory Computer		1	1		(3)
Set 1	Computer Mouse					1
Set 1	Dome Controller		1				1
Set 1	LX200 Telescope		1		1		1	USB to Serial
Set 1	SBIG Camera		1				1
Set 1	Optec TCF-S Focuser		1		1		1	USB to Serial
Set 1	ASI178MC Camera					1
Set 1	Dew Heater		1
Set 1	USB Hub 1		1			1	(4)
Set 2	AllSky Laptop		1	1		(2)
Set 2	Computer Mouse						1
Set 2	AllSky Archive Drive					1
Set 2	Oculus AllSky Camera		1				1
Set 2	Oregon Scientific Weather Stn						1
Set 2	Aurora Cloud Sensor		1		1		1	USB to Serial
Set 2	USB Hub 2		1			1	(4)
Set 3	Ethernet Hub		1
Set 3	General		1					Hairdryer / Flat Frame Sheet
Set 4	Light		1
	Total		14	2	3	11

Initial assessment indicates a maximum total observatory power consumption of 1728W (7.2A @ 240V), excluding hairdryer & assuming a 50% power efficicieny on AC adapters, or 3328W (13.9A @ 240V) including hairdryer.  Hairdryer (1600W, 6.6A) is the single most power-hungery item of equipment in the observatory and should only be used when other equipment isn't drawing high current.

Power Requirements (click image to view at full size)

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AllSky Laptop & Weather Data

Between 2015 and 2017 an always-on 'AllSky Computer' situated in the observatory has been used to control the capture and processing of AllSky Images, between sunset and sunrise each night. During observing sessions (but not in between times) the 'House Computer' captured weather station data (temperature, humidity, wind and pressure) and the 'Main Observing Laptop' captured sky temperature, cloud and rain data when an observing session was being conducted and the observatory the roof was open (which exposed the Cloud Sensor to the night sky).

In the new observatory it is intended that the 'AllSky Computer' takes on the role of capturing all weather and environmental data on a 24x7 basis, distributing this data to the 'Main Observing Computer' as required.

A number of things have begun to happen to make this possible:

1) A serious bug on AllSky imaging control program has been fixed and allows the AllSky laptop to run 24x7 without the AllSky Program and/or the laptop crashing.

2) A 4-port USB hub has been bought and connected to one of the two USB ports on the 'AllSky Computer'.  The 4 ports will be used for
   a) Mouse, b) Oculus AllSky Camera, c) USB  Communication Hub for talking with WMR180 base station d) Aurora Cloud Sensor

3) The USB Hub can be powered, but it is not yet known whether it will actually need to be powered or not, as the only device definately needing additional power is an external USB hard drive (used for Archiving AllSky images) which will be run directly from the other USB port on the laptop.

4) A Weather Station program (VMS), USB Communication Hub and my weather data repeater program have been installed on the 'AllSky' Computer and have run for 10 hours plus.  Testing continues but so far the VMS program running on 'AllSky laptop' has been shown to be able to succesfully access and read weather data from the WRM180 base station sitting on my kitchen window sill,  and forward the data to the Observatory Computer (for recording and information purposes) and to the AllSky Control Program (for annotating processed AllSky Images)

5) Addition of Graphs to VWS Display to show the desired weather information, and change Jpg file settings to output Jpg files at regular intervals (say every 20 minutes). A repeater program is then required to transfer weather graphs to the Observatory Control Laptop and/or upload to website (via FTP). This facility being unavailable within the basic edition of the VWS program that I have.

6) Aurora Cloud Sensor Program (v2 and v3) and Driver for Prolific PL2303 USB-to-Serial Adapter have been successfully installed on the AllSky Computer, and have run for 10 hours plus. A repeater program is required to forward Cloud and Rain Information to the Observatory Computer (for recording and information purposes) and to the AllSky Control Program (for annotating processed AllSky Images & Charts).

7) Move Aurora Cloud Sensor unit from inside the observatory to a position outside the observatory (to allow full-time access to the open sky). Cable length is easily long enough, but the method of fixing the Sensor Head outside needs to be defined.

8) Extend routine in AllSky Program to access and display Sky Clarity and Rain data on existing NightSummary  Plot.

9) Develop routines to use weather data to optimise telescopic imaging and observations and protect the Dome Observatory and equipment from rain or high winds by closing the Dome's shutter at first sign of adverse conditions.

10) Consideration may need to be given to future options such as adding a new CMOS camera & fisheye lens capable of taking both daytime and nighttime AllSky colour images.

Pictures below show show status of some of these improvements and changes in early 2018..

Cloud Sensor (2018-01-01)
Cloud Sensor box in new Outside Position
AllSky Kit & Cabling in Previous Observatory (2018-01-08)
AllSky USB Hub on middle shelf Comms to Oculus AllSky Camera, Cloud Sensor, Weather Station USB Hub Communicator & External USB Drive		Front Power Strip for AllSky Laptop & Connected Equipment 4-Port USB Hub, Oculus AllSky Camera Heater Cloud Sensor,  External USB Hard Drive
Nest of Cables on lower shelf / spilling onto floor in previous observatory Power Cables & Data Cables (USB, Serial, Ethernet) this is something that can be hopefully sorted out / improved on in the new observatory		Observatory Desk & Power/Data Hub (right) + USB Hub Communicator to Weather Station in previous observatory (fixed on cabinet in foreground, left)

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Cabling Plans

A series of Cabling Plans were drawn up for new observatory and are shown below.
Telescope Control and Imaging shows two options.   Option 1 was one initially used in new observatory and was largely based on system used in the previous observatory in 2017.  Option 2 shows an alternate design in which a Power/Comm Hub was brough and installed.   This is close to the design that was moved to in late 2018/early 2019 with the purchase of a Pegasus Powerbox (V1) .

Telescope Control and Imaging - option 1, based on existing setup (this was set up used during 2018, after which the setup migrated closer to that in Option 2 below)

Telescope Control and Imaging - option 2, based on using an all-in-one HUB solution  (A Pegasus PowerBox & USB Control Hub was installed in late 2018, with LX200 comms & power supply tranferred to Hub in 2019)

Observatory Bay 1 - AllSky Imaging, Weather, Ethernet Hub, Power Board (this is the setup that has been used through 2018-2020)

Observatory Bay 1 -  Power Panel and Dome Drive System (a dehumidifier hasn't yet been installed - as of 2020)

Observatory Bay 1 -  Power Panel and Dome Drive System (Red Light and Light Rope haven't yet been installed - as of 2020)

 

Altair Pegasus

Use of an Pegasus Ultimate PowerBox USB Control Hub (Altair), or similar system, could offer me a chance of reducing the cabling going to the telescope. Cost for the Alatir all-in-one solution  is however pretty high (£499) and its not certain whether it can be justified or not. It would be used
- dew heater control (2)
- power for focusers (2)
- USB cable to focusers (2)
- USB cable to ST-10XME camera (1)

It doesn't remove the need for a serial cable to Optec TCF-S Focuser, and may require the Focus Control/Handbox Unit to be mounted on the scope itself, rather than on the pier as at present.

The unit offers no significant benefits however with regard to
 - power for ST-10XME camera (ST-10 uses a special  12V, 12V, 5V AC Adpater adapter and 5 pin power cable
 - power for LX200 (this is can be more easily supplied by cabling from the pier)
 - control cable for the LX200 (this is more easiy supplied by RS232 cable (serial to USB) from the pier
-  USB cable to the ASI178MC camera, which requires a direct camera to computer connection to achieve the highest possible frame rates

The number of cables going to the Telescope Tube area (serving Imaging Cameras, Dew Heaters and Focusers) reduces from 7 to 4. This is a saving of 3 cables but at the expense of having extra kit (Optec TCF-S handbox and the Pegasus Control Hub) attached to the telescope tube/forks by some means.  The  Pegasus Powerbox would also reduce the number of required 240v power sockets by 2.

Update
UPB was purchased and installed on the Observatory Telescope in late 2018.  There were a number of teething problems mainly related to the Power Supply and it was not until mid 2019 that the system was working effectively.

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Computer Control

The observatory uses a Windows 7 computer that is hard-wired to many of the control systems and equipment in the observatory, including the Pulsar Dome with Rigel Dome & Shutter control,  LX200 GPS telescope & mount,   cameras (SBIG ST-10XME &  ZWO ASI 178MC) and focusers.  Currently the computer is a laptop which is brought into the observatory for each observing session.  In due course a dedicated observatory computer will be installed.

In addition to the observatory computer there is a server than manages file storage. All images captured by the observatory computer are stored on the server for processing later.

Finally there is also a separate environmental or weather server that is tied to a weather station (Oregon Scientific WM180R),  cloud/rain sensor (Aurora/Eurotech), machine readable online weather forcasts (darksky.net) and an all sky camera (Starlight XPress Oculus 180). The weather computer collects data from the various sources and uploads various charts, graphs and images to the internet and to the local server for display on the observatory web pages.  The weather server also monitors changes in the weather and accesses how suitable the weather conditions are for observing and whether it is safe or unsafe for opening the shutter on the observatory dome.  This information and certain other weather data  is sent to the observatory computer.  The weather server also recieves information from the observatory computer about where the telescope is pointing and the location of the next few planned targets.  The weather server returns information to the observatory computer about the presence or otherwise of cloud at the scope positon and at each of the next targets.  The weather server is currently an old laptop running Windows Vista, and just about manages to keep up with the computing load required, however it may be upgraded to a computer with faster CPU in due coarse.

An observatory management program running on the observatory computer uses information from the weather server, to decide whether to open the observatory dome for automated imaging when the sky is clear and dark, when to pause imaging or move to an other target when cloud encroaches and when to shutdown & close the observatory when heavy cloud, rain or daylight encroaches.

Communication between Observatory Computer and AllSky/Weather Computer is performed across LAN using a number of specific TCP/IP Ports.

Accurate time in the observatory is important for homing the telescope upon startup and other functions in the observatory, such as correctly recording the time that images are acquired. Computer time is kept current by constant updating from time servers on the internet using Dimension 4 software.

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Power Automation

Currently certain equipment is left on 24x7 (the observatory dome and the weather server and associated sensors) whilst certain other equipment (Observatory Computer/Telescope/Cameras/Focusers) are physically turned on at the start of each observing session.  In due course the turning on/off of equipment may be either automated or at least operated via remote control.

Currently (2018) there is no power back or plan to add any back-up.

Update 2024-02-28.
A UPS Backup to the Pegasus UPB Powerbox that distributes power to the LX200 Telescope is being considered as the telescope is the one item in the Observatory where even a very short power cut create a very significant problem with would result in a significant effort & delay to a live session in order to resolve and cause potential damage. This is because the telescope will turn off with out being parked, requiring its position to be resynced on a known star and a short mapping run completed. Whilst Program routines can aide the process it has to be done under strict user supervision & control.

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Dome Automation

Dome Automation will be enabled using my own Observatory Control Program running on the Observatory Computer with ASCOM & USB connection to the Pulsar Observatories Rigel Rotation Drive and Shutter Drive.

Weather information will be used to ensure the dome shutter is only opened when conditions match specific criteria (no rain and specific limits on cloud, wind and light) and automatically close when conditions become unsafe.  POTH.Hub is used to enable the Dome Position to be accurately slaved to the Telescope Pointing during the observing session.  [ Note: POTH.Hub was later replaced with DeviceHub ]

The Observatory Control Program has been updated to include a routine to open the shutter prior to observing and rotate it into the wind direction to facilitate the equilibration of the telescope, equipment and dome interior with the ambient air temperature.  Sensor information will be used to monitor the temperature difference between the inside of the observatory and the outside air temperature.

The dome will be parked in-between sessions at a position that allows the battery for the Shutter Drive to be topped up by induction charging.

The following online tutorial was found whilst researching Dome automation which proved useful
 :   ASCOM client astronomy development tutorial and introduction (YouTube)

Later work:
   Later work will be listed here....

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Imaging Automation

Image acquisition is can be performed under either manual, semi-automated or fully automated control. Automation is enabled using my own Observatory Control Program. This images a previously prepared target list by orchestrating all of the hardware and software in the observatory by directly monitoring and controlling:

- The LX200 mount for slewing and positioning the telescope with around 10 arc minute precision
- The SBIG camera, 10 position filter wheel and CCDSoft5 for capturing CCD images
- TheSky6 for plate solving and telescope positioning to around 10 arc minute precision
- Optec TCF-S focuser for focusing the telescope using my own focusing routines via CCDSoft
  and maintaining focus as temperature and filters change.
- PHD2 for autoguiding of LX200 scope using 80mm Guidescope and ASI 178MC camera
- Dome opening and closing
- Dome slewing and tracking (either directly or using POTH.Hub dome slaving)
- Weather and sky quality monitoring
- Taking dark flats and bias frames for image calibration
- SharpCap for alternate imaging using piggybacked 80mm scope and ASI 178MC camera.

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Final Plan

The final plan for the new Dome Observatory is similar to original outline plan, but includes a second bay, a circular pad and an adjusted position & orientation.   A plan view illustrationof the final plan is shown below

Final Plan for New Observatory

Construction Phase (late Mar-Apr 2018)

Demolishing Existing Shed Observatory

Photos below show the demolition of the existing roll-off roof observatory and removal its pier.
(The existing pier will be cleaned , shortened and reused in the new observatory)

Demolishing Old Roll-Off Roof Observatory (2018-03-25 to 2018-03-26)
Removal of heavy 2009 Roof (removed by taking off a wooden stop block and pushing the roof off the end of the support beams)		Old Pier Base (North is at top)
Removal of Shed Panels		Removal of Shed Panels
Rot at Bottom Corners of Shed		Rot at Bottom Corners of Shed
Rot at Base of Wooden Roof Support Columns (support posts snapped with only a moderate amount of force)		Rot at Base of Support Column (columns were 9 years old)
3 wheels found to have totally seized up  (explains why roof had become so difficult to open/close)		Seized Up Wheel - detail (Particularly severe abrasion on one of the seized wheels where it has rubbed along the top of the observatory wall)
Old Pier (Old pier is 114cm tall which is too tall for using in the new dome observatory, but will be shortened by 21cm in a fabrication workshop to make it suitable and at 25% of the cost of a new pier )		Old Pier Base (Pier base has become rusty after sitting on the ground below the observatory and will need to be thoroughly cleaned up for the using in the new observatory)

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Preparing New Observatory Site

Photos below capture the preparation of the new site / new pad during the first 10 days of April 2018.

Preparing New Observatory Site (2018-04-01 to 2018-04-03)
Marking out New Observatory site (2.5m diameter circle. Centre is offset from the old pier base to allow for the new base)		Setting & levelling marker posts for concrete pad (Pad will be 2.4m diameter. The site slopes by 15-20cm from left to right )
Surveying Completed (4 survey posts (N,E,S,W) have been added to allow site centre to be re-found using crossed strings after the central peg is removed when digging the new pier base)		Removal of Turf from Site
Hole For Concrete Pad (20cm deep on left around 2-3cm deep on right) Note: centre is disorted in picture due to image perspective		Posts installed around sides of hole and levelled (later these will support 20cm high circular shuttering with 2.4m diameter)
Further set of posts installed around sides of hole (to further support the shuttering for the 2.4m circular pad) Note: centre is disorted in picture due to image perspective		Hole for Concrete Pier Base (pier will be offset from centre of dome by 6.5cm in a southward direction - to the left in image below)
Side View (shows slope of ground across the site)		Hole for Concrete Pier Base (pier support sits on orange subsoil / glacial till)
Site in slightly drier conditions (wet muddy soil has been removed from base of pad, outer parts of old concrete pier have been hacked away) Note: centre is disorted in picture due to image perspective		Circular Hardboard Shuttering (shuttering installed and screwed tightly to support posts and a gravel base has been laid)
Concrete Pad (Wet Concrete about 1 hour after pouring) Volume 1.2 cu.m		Concrete Pad - side view (Wet Concrete about 1 hour after pouring)
Concrete Pad - shuttering removed (2 days after pouring)		Concrete Pad - side view (pad is reasonably circular)
Concrete Pad - edge view (surface is reasonably flat)		Concrete Pad - alternate view
Determining Centre of Pad (diameter measured in mutiple directions, with arcs of 1 radius length scribed for each diameter line) Note: centre is disorted in picture due to image perspective		Intersection of Arcs (centre chosen based on eyeballed average intersection of 1 radius length arcs)
Determining N-S Alignment (north-south alignment determined using shadow of plumb-bob line at local midday, this was at 01:09:03 BST on this particular day based on my  TheSky6 planetarium program)		Determining N-S Alignment (Picture shows shadow of plumb-bob passing through pre-determined centre of concrete pad. Position was then marked with pencil and a straight line drawn with the aid of a steel ruler)
N-S Alignment (picture showing north-south line scribed on concrete pad) Note: centre is disorted in picture due to image perspective		N-S Alignment (double checking N-S alignment line using magnetic compass. Magnetic north is 2 deg west of True North at my location)
Existing SWA Power Cable realigned for new observatory (excess cable would be cut later and the cable taken up through the base of one of the bays)

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Dome Arrival

Photos below show various shots of the dome and it components after it arrival in mid April 2018.

Dome Arrival (2018-04-10)
Wall Panels		Dome Roof Panels
Two Bays		Box with Dome Fixing Kit plus Dome Rotation & Shutter Drives
Contents of Box (Assembly Instructions,  also in the Box, are not shown in this picture)		Box Contents (from Left to Right) : Rotation Drive & Leads, Shutter Drive & Shutter Chain, Dome Fixing Kit (Wheels, Bolts, Nuts), Security Clamps, Pier Fixing Kit
Shutter Drive - front		Shutter Drive - back
Shutter Drive - bottom (showing connections)		Shutter Drive - Limit Switch
Shutter Drive Motor		Shutter Drive Motor Spindle
Rotation Drive & Control Panel		Rotation Drive Wheels (blue) & Encoder Wheel (grey)
Control Panel (base of panel, showing connections)		Rotation Drive Motors (bottom view, showing wiring)
Induction Charger		Induction Charger - side view

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Dome Preparation

Photos below show a selection of work/jobs undertaken in the week between dome arrival (2020-04-10) and dome assembly (2020-04-19).

Variety of jobs done whilst waiting to assemble the dome
Dome Wheels Fitted to Wall Quadrants		Dome Wheels
Damp Proof Membrane (membrane cut to circle)		Two packs for interlocking floor mats (£10 each from Halfords)
Laying out 12 interlocking floor mats (this had to be done carefully to ensure that holes could be filled by offcuts of sufficient size)		Filling in corners with offcuts  (pre-cutting the mats was going to be far easier than cutting them with the dome in place)
Floor mats cut to circular shape Note: centre is disorted in picture due to image perspective		Marking Pier Centre & Base Circumference (6cm offset from dome centre in due south direction
Mats with Pier Cutout (11 inch diameter)		Completed Mats (final job was to write a number (1 to 16) on the back of the mats to indicate layout)
Bay Cabinet Construction (2018-04-18)
Framework for one of the bay cabinet units started (Back legs need to be shorter than the front legs to allow for bay's geometry and obtain horizontal desktop. These were cut after dome had been assembled).		Desk surface cut to size (desktop is wider at front than the rear to allow for bay's geometry)  This cabinet is for main Power Panel and for AllSky/Weather monitoring

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Dome Assembly (2018-04-19)

Dome Assembly
Dome Roof Quadrant, Wall Quadrants and 2 Bays - Ready to Start
Dome Roof Quadrants, Concrete Pad		Assembling the Dome Roof
Dome Roof Completed		Dome Roof Completed
Assembling Dome Walls		Attaching Dome Walls to Concrete Pad
Dome Walls Completed		Ready to Lift Dome Roof onto Base
Fitting Observatory Bays (problem fitting central top bolt)		Fitting Observatory Bays (solution to fitting central top bolt)
Observatory Door		Observatory Assembly Completed

Follow Up Note

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Dome Roof Interior (2018-04-20 to 2018-05-01)

The Observatory Installation Guide states "To give a pleasing finish to the observatory interior, use matt black aerosol paint and carefully spray over dome top joins and bolt any other interior marks".  Since there were quite a few places where the supplied black matt finish was incomplete causing bright sunlight to show through or marks from dusty handmarks etc these were sprayed over as well.  

The observatory outfitting phase suffered lengthy delays as a number of different attempts where made to achieve an acceptable matt black finish to the interior of  the dome roof.   It took 5 different aerosols/paints before I found one that produced an acceptable finish.

1) I first used  Matt Black Rust-Oleum aerosol paint for spraying over joins and marks. Unfortunately the finish produced a satin and in places glossy finish rather than the expected matt finish and it contrasted strongly with the supplied matt black background, even after thoroughy drying.
I took the empty aerosol can back to B&Q, complained that the expected 'Perfect' Finish stated on the can was not perfect and got a full refund.

2) I painting over some of the aerosol sprayed areas with some spare water based matt black paint. This was better, but still left a noticeable
contrast with the supplied matt black background.  I didn't have enough of this paint to repaint the entire interior.

3) I then bought and applied a tin of Blackfriars Matt Black Paint (white spirit solvent). The finish was again poor.  Maybe the paint hadn't mixed or had thickend towards the bottom of the can, but some parts had dried to a shiny like gloss. Even the matt areas were somewhat patchy.

4) I then bought and applied a tin of Johnstone's Matt Black Paint (again white spirit solvent).  The paint was very slow to dry and worried that overnight condensation would affect the paint I left on upstanding light on in the observatory overnight.   The result was that the areas of the dome interior in shadow dried with a matt finish, whilst the areas in direct light dried with a gloss finish ! . Same paint / same application.

5) It wasn't until I bought and applied a tin of Delux Matt Black Emulsion (water solvent) that I finally got a finish that I was content with.

Dome Roof Interior - after 'touching up' with matt black aerosol spray paint (2018-04-21)
Roof Interior - after using Matt Black Aerosol (without flash)		Roof Interior - after using Matt Black Aerosol (with flash)
Roof Interior - after using Matt Black Aerosol (definately not a pleasing finish)
Dome Roof Interior - attempted repaint job with Johnstone's Matt Black Paint  (2018-04-29)
Roof Interior - attempted repaint (paint taking a very long time to dry, and a upward pointing light was left on in observatory overnight to prevent condensation forming on the still wet paint, result was that shadow zone (bottom)  dried with a matt finish , whilst the lit zone (top) dried with a gloss finish - same paint/same application !		Roof Interior - attempted repaint (patchy finish)
Roof Interior - attempted repaint (patchy finish)		Roof Interior - attempted repaint (patchy finish)
Dome Roof Interior - Final Paint Job with Delux Matt Black Emulsion (2018-05-01)
Roof Interior - final finish (after remedial painting with Dulux black matt emulsion)		Roof Interior - final finish
Roof Interior - final finish		Roof Interior - final finish

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Dome Outfitting (2018-04-20 to 2018-05-02)

Pictures below show the outfitting of the new dome observatory.   The pictures have been arranged in a logical order but the subject groups are not necessarily presented in the exact order that equipment was built and/or installed.  The outfitting phase was stretched out due to issues with achieving an acceptable dome roof interior.

Outfitting comprised

- Dome Clamps
- Pier (including Top Plate & Wedge)
- Flooring
- Telescope
- Bay Cabinets
- Observatory Power (including Bay to Bay conduits)
- Dome Rotation Drive & Controller (including Induction Charger)
- Cabling & Telescope Accessories
- AllSky Camera/Cloud Sensor Mast

- Completed Observatory

Dome Clamps (2018-04-20)
Dome Clamps (one of four dome clamps that are designed to provide a permanent in-place security to prevent the dome roof from lifting in strong wind or from being removed )		Dome Clamps - Fitting Issue Unfortuantely there was a problem with the clamps I was initially supplied with as the slots for taking the retaining bolts didn't align with the wall flanges. (replacement clamps were eventually recieved from Pulsar Observatories and installed on 2018-10-03)
Shutter Drive (2018-04-21)
Shutter Drive - initial installation (Note: cable to motors should be inserted into base of shutter unit before attaching drive unit to observatory roof, it can't be inserted with unit attached !)		Attaching Drive Motor Cable (cable is impossible to retrospectively attach with the drive unit already attached to the dome roof)
Drive Motor Cable finally attached (Note: cable attached after taking Shutter Drive Unit off the Roof, notice how cable has to be bent sharply to get it to attach)		Shutter Drive Cable (show cable passing through pulley and  its attachment to shutter)
Dome Roof Flange (Roof flange filed to ensure that it doesn't interfer with the passage of the dome drive chain)		Shutter Drive Chain
Shutter Drive Unit		Shutter Upper Stop
Pier Installation (2018-04-28 to 2018-05-02)
Shortened Pier (Pier after being shortened to a new height of 93cm by a local fabrication workshop) (see original pre-shortened pier)		Pier with grey primer (black satin paint failed to attach directly to red-oxide on first paint attempt, requiring the red-oxide to be rubbed  and over painted with a grey primer before reapplying black top coat)
Aligning Pier with earlier N-S line (pier laid over a scribed circle centred on planned pier position, and rotated so that south side of pier is precisely aligned with earlier N-S alignment line, centre of 4 pier holes then scribed on concrete floor)		Preparing Holes for Pier Bolts (pier, SDS drill, studs, vacum Cleaner)
Drilling holes with SDS drill & 22mm masonary bit (holes were piloted with a smaller bit beforehand)		Cleaning hole of debris with homemade vaccum attachment
Checking Pier Holes with Pier Base		Cleaning sides of hole with dry brush
Cleaning hole with dry brush		Cleaning hole with wet brush
Pier studs with used tube of J-Fix Polyester Resin		Pier studs in place
Waiting for resin to firmly set before locking down nuts
Final Pier Alignment Check (checking that Pier will be aligned with earlier N-S Alignment Line before bolting it down)		Pier Installed
Final Pier Alignment Check (checking that Pier will be aligned with earlier N-S Alignment Line before bolting it down)		Pier Installed (top view)
Installing Top Plate (checking that Top Plate is horizontal in the E-W direction)		Installing Top Plate (checking that Top Plate is horizontal in the N-S direction, this direction is less important as any discrepencies in that direction can be corrected when adjusting the wedge inclination during polar alignment)
Top Plate Installed		Top Plate Installed
Checking that wedge is horizontal in E-W direction		Wedge Installed On Pier
Flooring Installation (2018-05-02)
Damp Proof Membrane (membrane cut prior to dome assembly)		Interlocking Floor Mats (mats cut prior to dome assembly) centre is disorted in picture due to image perspective
Damp Proof Membrane Installed		Installing Interlocking Floor Mats
Installing Interlocking Floor Mats		Cutting slots for the wall flanges (these 4 corner mats were left to last)
Floor Mats Installed		Floor Mats Installed (top view)
Telescope Installation (2018-05-02)
Temporary platform (platform built to aid entry of heavy 12" LX200 into dome)		12" LX200 about to enter observatory
LX200 telescope installed in dome		LX200 telescope installed in dome
Bay Cabinet Installation
Cabinet in Bay 1 (Power Panel &  AllSky/Weather Monitoring)  Desktop later reduced from 54cm to 48cm depth to prevent water of condensation dripping from roof interior		Cabinet in Bay 2 (Telescope / Observatory Control)  Desktop & lower shelf later reduced from 55cm to 48cm depth
Cabinet in Bay 2 (Telescope / Observatory Control)  Picture shows cabinet after reducing Desktop/Shelf Depth and after fitting leads to telescope		Cabinet in Bay 2 (Desktop for Telescope / Observatory Control)  Power Lead, Ethernet Cable & USB3 cable for ASI ZWO camera on left,  USB cable to Hub and Mouse on right)
Observatory Stool (Stool taken from old observatory and modified to reduce its height to make it suitable for working at the height of the cabinet desktops and to add a flat base to avoid leg indents on the interlocking rubberised floor mats)
Observatory Power Installation (2018-04-21)
Existing SWA Power Cable realigned for new observatory (excess cable would be cut later and the cable taken up through the base of one of the bays)		Preparing SWA Cable for tie-in (cable taken up through a 20mm conduit in base of Bay 1)
Power Panel under Cabinet in Bay 1 (7 sockets compared to 5 sockets in original design)		SWA Cable hooked up to Power Panel (note a RCD is located at the house end of the SWA Cable)
Power and Data Conduits between Bays (2018-04-25)
Flexible Conduits travelling between two bays One conduit carries power from Power Panel Bay (left) to Telescope Bay (right). The second conduit carries Ethernet cable and plus a USB cable for operating the Dome Drive.		Flexible Conduit for taking Power & Data (25mm flexible conduit and glands)
Data Cables about to be inserted into Flexible Conduit (1 USB, 1 Ethernet)  (lug on ethernet connection is held down with tape to prevent it sticking in the conduit)		Data Cables emerging from end of conduit (tape has had to be used to cover over sharp or square edges on the two connnectors, tape also had to be used to increase  the rigidity of the inserted cables and enable the cables to be pushed through to the end)
Cabinet in Bay 2 (Telescope Control Bay) Picture taken after running power/data cables from Bay 1, but before fitting shelves and desktop		Power Cables & Data Cables emerging from conduits (Telescope Control Bay)
Cables emerging from 25mm conduits at bottom of bay 2		Power Cables & Data Cables emerging from conduits (Power Panel/AllSky Camera Control Bay)
Power Strip under cabinet in Bay 1 (AllSky Camera & Weather)		Power Strip under cabinet in Bay 2 (Telescope/Observatory Control)
Cable Protector/Guide Addition of protector on 2018-05-23 may have been responsible for a series of Telescope Communication Errors seen during the next two sessions by pressing too tightly on RS232 Cable to the Scope (this was later fixed by relieving the pressure on cable)
Observatory Lights (2018-05-07)
Light & Light Switch (with dimmer) next to door		Light & Light Switch (with dimmer)
Dome Rotation Drive & Controller (2020-04-29)
Rotation Drive & Control Panel (unit prior to installing)		Rotation Drive Wheels (blue) & Encoder Wheel (grey) (unit prior to installing)
Over-stretched Spring on encoder arm (spring on encoder arm that became irrepairably overstretched when front motor / driver controller was removed from back motor plate without unhooking the spring)		Temporary Workaround /  'Bush Fix' (elastic loop wrapped around encoder block to keep  encoder wheel tensioned against the roof flange)
Conduit for 12V Power Cable & USB Cable to Dome Drive Controller (2020-04-29)
White conduit taking 12V power line & USB control cable		Picture showing detailed view of top and bottoms of conduit
Induction Charger (2018-05-02)
Induction Charger - front view (installed above Rotation Drive, charges the shutter drive in the roof using induction, no direct leads !)		Induction Charger - side view (gaps ranges from 8 to 10mm)
Dome Controller		Dome Controller - LCD screen (showing shutter battery status)
Cabling and Telescope Accessories (2018-05-07)
Optec-TCF-S focuser & ST-10 Camera connected to Scope.  USB 3 cable is for ASI ZWO camera (not yet attached)		Cables to/from Telescope (Optec TCF-S controller box mounted on pier)
Cables to/from Telescope (orange string is a trial attempt to carry weight of cables from back of scope and stop them dragging across the floor)		Cables to/from Cabinet in Bay 2
Telrad attached to dovetail & 12" LX200GPS Telrad has been screwed to a male dovetail, taken from Meade finder scope that is not used, to provide a more secure attachment than the normal sticky pad attachments
AllSky Camera/Cloud Sensor Mast (2018-04-29)
AllSky Camera & Cloud Sensor Mast (mounted on mast on the north side of the Dome)		AllSky Camera / Cloud Sensor Closeup
AllSky Camera (Camera poking above the observatory roofline, camera is mounted on mast on the north side of the Dome)		AllSky Camera Closeup
Associated AllSky/Weather Accessories in Cabinet in Bay 1 (top down view, prior to fitting desktop, showing Powerstrip with plugs/adapters (left),  USB Hub & USB Hard Drive (centre),  LAN Hub & Weather Station USB Hub (right) )
Completed Observatory (2018-05-07)
Completed Observatory		Completed Observatory

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Commissioning Phase (May-Jun 2018)

Observatory Commissioning

• Commissioning Phase Aims
• Observatory Issues and Unfinished Work (left over from the Construction Phase)
• POTH.Hub
• Dome Controller
• Observatory Control Software
• Main Scope Setup (12" LX200GPS/R)
• Observing Limits
• Telescope Leads
• Additional Equipment Required
• Commissioning Logs / Results
• First Light Image

Commissioning Phase Aims

Aims for the commissioning phase:

- Identify and rectify issues relating to the design, assembly and kitting out of the observatory
- Configure POTH.Hub for operating LX200 Scope and Pulsar Dome together
- Identify any issues relating to the Dome Controller
- Test observatory control software (identify/fix any bugs, identity/prioritise any useful enhancements)
- Set up main scope (Telrad Alignment, Polar Alignment, Periodic Error Testing & Correction, Telescope Balance)
- Log commissioning results
- Identify static and dynamic observing limits (zenith limits, guidescope limits, observing horizon & wind conditions)
- Optimise telescope leads
- Identify any additional equipment requirements

Observatory Issues and Unfinished Work

- Trip Hazard from Temporary Slab in front of Dome (fixed, 2018-05-07)
- Slabs to be laid leading to the observatory and below door (done, 2018-05-08)
- Gravel to be load along the front edge of the observatory pad (done, 2018-05-10)
- Silicon lubricant to be added to shutter chain (done)
- Water issues associated with leaks and condensation (fixed, monitored & signed off 2018-07-31)
- Flimsy door bends under its own weight and encourages forcing of door by potential intruder (fixed, 2018-08-06)
- Stutter, slackness in chain during shutter opening/closing (fixed, 2018-08-22, fixed 2021-01-15)

- Dome Clamp Fitting Issue (fixed 2018-10-03)
- Potential Snow entry through the gap between shutter and dome roof near zenith (snow protection routine for automatically rotating roof to minimise risk
- Stutter during dome rotation (fixed 2021-01-15)
- Slabs to be laid around the rear side of the observatory (still open)

POTH.Hub

Dome Geometry set up in Poth.Hub properties:

Dome Controller

- Dome Slaving (checked, 2018-05-05)
- Dome Shutter Pointing (checked, 2018-05-05)

Issues:
  - Pulsar Dome switching back and forth between USB Serial Port COM9 and COM11 (2018-05-05) (Details)
  - Incidence where Slaved Dome operating around azimuth 70deg +/-, whilst scope operating around azimuth 190 deg +/- (2018-05-05)
  - 'Unexpected' Dome Movements as the Dome synchronises every few minutes with Telescope Pointing  (2018-05-05)
   (can Dome be set to move at 1.0x sidereal and be slaved at same time to alleviate this problem ? )
 - Shutter battery shows maximum charge of 51% (2018-05-03)

Observatory Control Software

The following problems were identified and have been fixed:

- Cloud Sensor UTC times not converted to BST time  (fixed, 2018-04-29)
- Sun information being accessed by Observatory Manager thread every 30s interferes
    with user's use of TheSky program (part fixed, 2018-05-05)
- Program crash whilst performing plate solution attempts (fixed, 2018-05-05)
- DarkSky.Net UTC times not converted to BST time (fixed, 2018-05-07)

The following problems were also identified but remain open,  i.e. are unfixed:

- Unexpected alerts from Obs.Manager reporting that A/C power has been off for 20 minutes (open)

Following enhancements are identified

- Instruct dome to 1.0x sidereal (ie tracking),  Instruct Dome to 0.0x sidereal (ie stopped) - Medium Priority
- Access Shutter Battery reading and issue alerts as appropriate and close shutter or not open till battery charge is acceptable - Medium Priority

Rotation Rate of Dome (sidereal) must be set to 0.00x sidereal when using POTH.Hub's Slave Dome function.  If not TheSky6 doesn't recognize that a telescope slew has been completed (as it sees that Dome is still moving). As a consequence the control program doesn't respond with the next program step

Main Scope Setup (12" LX200GPS/R)

Tasks Completed :

- Focusing (ok, 2018-05-05 & 2018-05-17)
- Main Camera Alignment (ok, 2018-05-05, ~180 deg (N down) due to camera leads)
- Telrad Alignment (done, 2018-05-05 , Arcturus)
- Synchronise on Object (done, 2018-05-05, Arcturus)
- Set Telescope Park Position (done, 2018-05-05, Alt 0 deg, Az 180 deg)

- Set Scope to get Time/Date from Computer via POTH Hub (done, 2018-05-05)
- Provisional Polar Alignment (done, 2018-05-10 / 2018-05-)
- Periodic Error Measurement (done, 2018-05-13))
- Set Scope to not use GPS (done, required as guidescope presence stops the LX200 from getting a GPS fix)
- PEC curves uploaded (done, 2018-05-16)
- TPoint Mapping (first run done, 2018-05-17))
- GuideScope focus and alignment (done, 2018-05-22)
- Map Local Horizon (done, 2018-05-22)
- Clear View Checks, including Zenith (done, 2018-05-22)
- Observing Run using Computer Generated Schedule & Automated Execution (done, 2018-06-11)
- Stress Test (done, 2018-06-13)

Tasks To Do :
- Fine tune Polar Alignment (to do)
- Collimination (to do)

Observing Limits

Local Horizon Mapped :

Mapped Horizon (Horizon Altitude varies between 0 and 14 deg)

Telescope Leads

- Slewing Safety Check, looking at Telescope/Camera cable travel was successfully conducted ahead of session on 2018-05-17 (pictures). No telescope lead issues surfaced during mapping of 121 points during session itself
- 12V Cigarette Lighter Connector became accidently disconnected during session on 2018-05-17 causing dew heater to go offline.
 (a better solution is required)
- Addition of a cable protector/guide on 2018-05-23 may have been responsible for a series of Telescope Communication Errors seen during the next two sessions by pressing too tightly on RS232 Cable to the Scope (this was later fixed by relieving the pressure on cable)

Additional Equipment Required

Additional equipment required

- focuser controller for 80mm guidescope
- LED strip lights for Cabinet/Bays
- Dehumidifier

- Completed : Extra Floor Strip for carrying cables across floor from cabinet to scope
- Completed : Interior Door Mat
- Completed : New 12" Dew Strip to place inside Dew Shield (purchased but not yet fitted)
 

Commissioning Logs / Results

Commissioning Session	ID		Test / Task		Result		Highlights
2018-05-05	S610.1		Start Up		Issues		Partly successful, but several issues.
(night-time)			Control Program		Issues		Critical problems encountered with Observatory Control Program
			Focus		Ok		Adequate for commissioning setup and tests
			Camera Orientation		Ok		(Orientation 180.0 deg+/-)
			Telrad Alignment		Ok		(Took a long time)
			Centre Align Star & Sync		Ok		(Arcturus)
			Set Park Position		Ok		(Az 180, Alt 0)
			System Stability		Issues		Issues with Dome Com Port jumping and Slaving/Telescope LST
2018-05-08	S610.2		Start up & Slaving		Ok		POTH.Hub connected & functioning ok
(night-time)			Centre Align Star & Sync		Ok		(Arcturus)
			Polar Alignment		Fail		Not achieved due to developing cloud.
			Parking / Close Down		Ok		Earlier alert message problem fixed
			System Stability		Ok		Session was short
2018-05-10	S610.3		Periodic Error		Ok		Successful check. Normal PE trace (35" peak-to-peak, PEC off) - Graphs
(night-time)			RA Motor Unit		Ok		Confirmation that installation of new RA motor unit giving required benefits
			Polar Alignment		Ok		Provisional Alignment Completed (~ 2' Azim / 0.2' Alt) - Graphs
			System Stability		Issue		Issue with Telescope/POTH loosing the correct LST
2018-05-11	S610.4		Trun off GPS		Ok		GPS Turned off (allows 80mm guidescope to be left on between sessions with GPS Fix issues at next start-up
(daytime)			Auto Time Update		Ok		Time updated to Computer's Time upon Scope connection
2018-05-13	S610.5		Start Up		Ok
(night-time)			Periodic Error		OK		RA tracking measured across 2 x 24min worm cycles
			PEC Upload		Fail		PEC curve not correctly sychronised to Worm Segment Counter (shifted curve prepared ready for upload at next session. - Graphs)
			Remote Control		Ok		Observatory operated under remote control for part of session
			Polar Alignment		Ok		Alignment further refined using PemPro Wizard - Graphs (alignment estimated to be within 1.5 arc min of Celestrial Pole)
			System Stability		OK		System not pushed excessively
2018-05-16	S610		PEC Upload		Ok		PEC Curves successfully uploaded to mount.
(night-time)			Periodic Error		Ok		Residual PE Error used to further refine PEC curves (2 iterations), PE < +/- 3 arc mins - Graphs
			First Images		Ok		First set of images taken, including unguided images with up to 180s exposure.- Images (S610)
			System Stability		Ok		System stable throughout session.
			Remote Control		Ok		Observatory operated under remote control for majority of session. (Observatory opened and closed from inside house.)
			Flat Frames		Ok		Sets of Flat Frames where acquired with C filter
2018-05-17	S611		Slewing Safety		Ok		Slewing Safety Check successfully conducted (Pictures)
(day-time)
2018-05-17	S611		Focus		Ok		Semi-Automated focusing run successfully conducted (Details).
(night-time)			TPoint Mapping		Ok		121 points successfully mapped (25% Automap rejection with Error Code 653)
			TPoint Model		Ok		TPoint Model built (Details), polar alignment elevation ME sensitive to other terms used in the mode.
			Polar Alignment Review		Ok (part)		Polar Alignment Information from TPoint run (Polar Alignment review)
			System Stability		OK		System stable throughout session.
2018-05-22	S611.2		Align Guidescope		Ok		Guidescope aligned with LX200 Main Scope
(day-time)			Map Local Horizon		Ok		Local Horizon mapped and uploaded to TheSky6  (Details)
			Clear View Checks		Ok		Clear View Checks completed, including checks around Zenith (Some issues near to Zenith)
			System Stability		Issue		System generally stable but a couple of glitches noticed that could be problematic for unattended operation
2018-06-06	S612		TPoint Model		Ok		Synced into TPoint Model
(night-time)			Images		Ok		Partly achieved with images of Jupiter & its moons (Pictures)
			Observing Plan		Fail		Not achieved due to POTH/Scope/CCDSoft Instability (Observing plan)
			System Stability		Fail		System very unstable with frequent disconnections to tthe Scope. Also problems with Dome COM port (9 & 11), freezing of CCDSoft, and upset to scope's LST  (Operational issues)
2018-06-08 (day-time)	S612.2		Observing Plan		Ok		Observing Plan successfully executed using live observatory hardware, but without plate solution/centering (no stars in daytime) (Observing plan)
			System Stability		Issue		System initially unstable with disconnection to scope, freezing of CCDSoft5 (Operational issues)
2018-06-11 (night-time)	S613		Observing Plan		Part OK		5 Targets successfully acquired with automated execution of computer generated observing plan / schedule.  Issues with accuracy and time take for high precision target centering, time overruns and missed start times for following target. (Observing plan)
			Images		Ok		Some images acquired (Pictures)
			System Stability		Fail		System very unstable in first half of session with frequent incidences of telescope communication error '213' / automatic termination of telescope link. Also problems with freezing of CCDSoft5 and Dome COM port switching (9 & 11)  as side-effect of '213' error. (Operational issues)
			AllSky		Fail		AllSky Laptop failed with a terminal hard disk failure (Failure & Replacement)
2018-06-13 (day-time)	S613.2		Stress Test		Ok		2 hour long Observing Plan (74 target) successfully executed using live observatory hardware & software, but without plate solution/centering (no stars in daytime) (System Stress test)
			System Stability		Ok		System stable, without any repetition of telescope communication error '213'

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First Light Image (M13)

First Light Image from the new observatory, 2018-05-17 M13, Globular Cluster (Hercules)

CCD Image (100% size, cropped, logscale),  7 x 10s exposure (average combine), 2x2 binning, C Filter 2018-05-17  00:25 h UT (#610045-51) 12" LX200R  (at f/10.4) + ST-10XME

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Issues & Fixes (May - June 2018)

• Dome Clamps
• Condensation on Roof Interior
• Small water leaks above each bay
• Cabinet Remediation
• Water leak (pulley fitting in roof)
• Telescope Communication Errors
  

Dome Clamps
Dome Clamps - Fitting Issue (2018-04-21) A problem was noted with the batch of dome clamps I was initially supplied with. The slots for taking retaining bolts didn't align with the wall flanges) (replacement clamps are due to be sent out in due course.  They are understood to be sent out soon - Sep 2018)
Condensation on Roof Interior (2018-04-21) Condensation was particularly bad during the first two weeks, but settled down over the summer months.  It will be monitored as the winter season is approached to see if a Dehumidifier is required.
Condensation on roof interior (high up on ceiling)		Condensation on roof interior (detail)
Water drip lines related to condensation on roof interior (taken before Dome Roof Paint Remediation)		Water drip line on shutter interior
Water drops from Small Leak along  top of Bay		Water drops from small leak along  top edge of one of the bays
Small Water Leaks Above Each Bay (2018-04-25)
Top of Bay		Photo showing earlier problem fitting Observatory Bay
Water drops from Small Leak along  top of Bay		Water drops from small leak along  top edge of one of the bays
Outside view showing leak path along top edge of bay (gap was later sealed with silicone)		Outside view showing leak path along top edge of bay (alternate view)
Cabinet Remediation (2018-05-01)
Water drip lines related to condensation on roof interior (drip lines like these fall down on to original cabinet desktops before being reduced in depth,  drips will now fall onto floor from where water can safely evaporate (taken before Dome Roof Paint Remediation)		Reducing Desktop /Shelf Depth (original surfaces were made with depth of up to 55cm, but water drops from heavy condensation one frosty night fell on to the surfaces damaging them in the process, The work surfaces were cut back to a maximum depth of 48cm so that they lay entirely within the bay)
Water Leak (2018-05-02)
Water Streak on roof interior (indicating a leak from somewhere in the upper roof, investigation shows this was due to rain entering from uppermost pulley fixing)		Wet patch near uppermost pulley fixing (indicating a water leak from uppermost pulley fixing
Water Drip from bolt holding uppermost pulley (investigation showed that one nut holding the fixing was loose, this was loosened whilst adjusting the pulley and evidently hadn't been retightened)
Telescope Communication Errors (2018-06-06 to 2018-06-13)
Cable Protector/Guide added on 2018-05-23 Protector addition may have given rise to Intermittent Telescope Communication Errors by pressing too tightly in RS232 Cable to Scope		Cable Protector/Guide   Recently added Cable Protector loosened to relieve pressure on RS-232 Cable Cable Connections fully checked

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Ramp Up Phase (Jul-Aug 2018)

Ramp Up Phase

Ramp-up phase is the intended to gradually move the observatory into full operation, by
- ironing out any remaining bugs and issues in the system prior to the forthcoming winter season,
- adding and testing a key software enhancement to enable fully-automated operation.
- increasing the time devoted to taking proper astronomical images and to scientific programs.

Automated Operation Testing (Jul 2018)

Aims for the automated operation testing phase:

- Test routines in Observatory Control Software (CCDApp2) that are designed to provided Fully-Automated Operation capability
- Identify and rectify issues relating automated operation of the observatory
- Ensure that robust safeguards are in place to ensure that automated operation is safe
  particularly with regard to shutter opening/closing.
- Continue to test and prove system stability, and iron out any remaining issues with the observatory.

Automated Operation Testing  - Results & Highlights

Session	Test / Task		Result		Highlights
2018-07-18 (night-time)	Fully Automated Test		Issues		Observatory System placed in Fully Automated Mode, which generally worked ok except that target slewing/imaging commenced with the Dome Shutter still shut (not opened due to adverse weather (cloud), which is in itself a positive result) (fully automated test)
	System Stability		Ok		System stable, without any repetition of telescope communication error '213' (Unable to 'unpark scope' however after parking at end of session)
	AllSky		Ok		AllSky & Weather Montoring Services back in action following incorporation of a replacement Laptop that was brought into service on ~2018-06-25+
2018-07-22 S614	Fully Automated Test		Issues		Observatory System placed in Fully Automated Mode and ran for second half of the night. (fully automated test)
	System Stability		Ok		System stable
	AllSky		Ok		Annototion of AllSky Visible Stars back in action following update to SExtractor settings.
2018-07-24 S615	Fully Automated Test		Issues		Observatory System placed in Fully Automated Mode and ran for second half of the night.   (fully automated test)
	Observing Plan		Issues		Low imaging efficiency due to target observations overunning their allotted time slot causing the following target observation to be missed leading to wasted time whilst execution waits until the scheduled start time of the next planned observation.  Mosaic Frame Imaging  Mosaic Failed Fix to Mosaic Inaging worked.
	System Stability		Ok		System stable.
	AllSky		Fail		Outage of Cloud Detector (fixed by manually disconnecting and then reconnecting USB and Power cables)
2018-07-25 S616	Fully Automated Test		Ok		Observatory System run in Fully Automated Mode for entire night. Newly added code to skip final image(s) to ensure target observation finishes within allotted time slot (and ensuring that the next target observation isn't missed) worked perfectly  (fully automated test)
	Observing Plan		Ok		Newly added code to skip final image(s) to ensure target observation finishes within allotted time slot (and ensuring that the next target observation isn't missed) worked perfectly.  Fix to Mosaic Frame Imaging worked.
	System Stability		Ok		System stable.
	Monitoring		Fail		Indoor Desktop Computer out of action with terminal hard disk failure (C Drive) (Fall-back is to use UltraVNC from IPad)

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Later Observatory Fixes and Enhancements (Aug 2018 - Jan 2019)

Observatory Door Improvement (2018-08-06)

It was quickly noted after assembly and first use that the door supplied with Pulsar 2.2m dome observatory is very flimsy and easy bends /wobbles under its own weight when its open.  I finally got around to having the observatory door stiffened up using shaped wood & fiberglass cross-pieces in August 2018.  The remediation was performed at a local fiberglass workshop for £60.

Observatory Door - as supplied Flimsy & bends too easily under its own weight		Observatory Door - stiffened Door stiffened up by the addition of shaped wood & fibreglass cross pieces

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Shutter Drive Unit - Reinstallation (2018-08-22)

After using the Shutter Drive for a while it became obvious that its position wasn't sufficiently correct and that there was a misalignment between the drive sprocket and the line of the plastic chain that pulls the shutter open and closed (a risk of a self-installing a dome for the first time). Slack chain would develop close to the drive unit when the shutter began to open until the shutter reached the first xxxx.  leaving one with some lack of confidence in the system.  No amount of tension adjustment was able to stop this slack from developing.  It was also apparent that there would probably be long term wear on the side of the plastic chain that pushed against the metal drive sprocket the most, with eventual risk of failure. There might also be some extra wear on the connection of the sprocket to the drive axis or on the drive axis itself.    Relocation the shutter drive unit so that the drive sprocket would align perfecting with the chain was put down as a 'task to do' - a job to do some time before the winter season.  

The need for this remedial fix came to head following an incident during the observing session on 2018-08-21 when the chain jumped  off the drive sprocket when the motor tried to open the shutter from a closed position.    With the shutter not moving and unable to close the relay at top of dome, the motor continued running for 45 minutes in a vain attempt to open the shutter before the observatory was visited and drive turned off. The problem wasn't picked up via remote monitoring as the observatory control program was putting out continuous messages that it was closing the shutter due to cloud, wind and threat of rain (from local rain radar).  The incident highlighted several things, but among them was the need to correct the current installation deficiencies and relocate the shutter drive in order to prevent or strongly reduce the risk of another chain problem in the future.

Pictures below taken whilst re-locating the shutter drive unit the following day (2018-08-22). The drive unit was shifted across by 10mm. It was noticed that the drive sprocket was somewhat loose and the opportunity was taken to correctly position the position it on the axle and tighten up the retaining grub screw with a suitable Allen key. It was necessary to move the bracket that comes in contact the relay attached to the shutter drive unit to ensure reliable closure of the relay. This was by a small amount only as the bracket still had to reliably hit the relay at the top of shutter travel.  The chain is now perfectly aligned with the drive sprocket and works more smoothly, and my confidence in the system is again restored.

It is noted that a slack in the chain on the 'downstream' of the drive sprocket is still created in the process of opening the shutter.  Hopefully with the perfectly aligned chain/drive sprocket the chain can't manage to crawl its way off the sprocket.
(The slackness created when opening the dome appears to highlight a weakness in shutter system due to the inherent changes in the total direct path distance around the various pulley wheels and sprocket as the shutter open/closes. Ideally the system would incorporate a 'tension wheel' that would maintain a constant tension in the chain whatever the position of the shutter.)

Shutter Drive Unit removed (a piece of timber (out of view) is being used to hold the shutter open)		New Holes drilled (10mm to right of original holes)
Re-Installing Shutter Drive Unit (Old holes covered on the inside with tape and then filled from outside with white sealant. They end up largely covered by the washers on the new holes)		Shutter Drive Unit installed in the new position
Chain reattached to Drive Unit (Chain run is now perfectly straight)		Chain aligned with drive sprocket
View of Chain with shutter closed (chain is nicely tight)		View of Chain with shutter partly opened (chain goes slack on downstream side of the drive sprocket when the total direct path length reduces - this highlights an ongoing weakness in shutter system, but eventually fixed in Jan 2021

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New Dome Clamps (2018-10-03)

The Dome Clamps that were originally supplied with the Pulsar Dome Order in April 2018 didn't fit, as the slots for taking the retaining bolts didn't align with the wall flanges.  Apparently the clamps sent out by Pulsar Observatories at this time had used the clamp design associated with the wall-less Dome and not for the walled Dome, and a new batch needed to be manufactured. The new clamps were finally delieved in late September 2018 and where successfully fitted in the observatory on 2018-10-03. 

There are four dome clamps that are designed to provide a permanent in-place security to prevent the dome roof from lifting in strong wind or from being removed.  Whilst the observatory gave no indication that the roof would be likely to lift in winds, the observatory site is close to the sea and pretty exposed to the winds. Having previously had my roll-off roof blown off  former shed observatories  I'm very pleased to have new clamps installed before the inevitable autumnal/winter storms arrive.

New Dome Clamps (finally delivered and fitted)

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Relay Protection - hardware based closure of Dome in the event of Cloud/Rain (2019-01-12)

• During risk assessment for unattended operation of the Observatory it was identified that there was a need for automated closure of the Dome Shutter in the event that either my Observatory Control Program (AstroMain) locks up or the Observatory Computer itself freezes/dies and were consequently unable to command the Dome to close in the event of rain.
  
  [ My AstroGuard program provides some protection in the event that the AstroMain program doesn't command the shutter to close when it starts to cloud over or rain begins and my AstroProtect program provides protection in the event that the Observatory Computer automatically restarts after a computer crash.  However neither are effective if
    a) the Observatory Computer freezes or totally fails,  or
    b) the COM connection to the Dome Controller goes down or otherwise fails ]
   
• It was identified that there is a protective Relay port on the bottom of the Dome Controller which could provide the required additional protection if it could be hooked up with the protective Relay output from my Eurotech Cloud Sensor and operated on the basis of a set of Thresholds saved in the Sensor Head.
  
  Photo showing base of Pulsar Dome Controller
     
  
  Eurotech CloudSensor (left) including Rain & Light Sensors
    
   
  
• The Eurotech Cloud Sensor manual provided some information about it's Alert Relay
  
  
  
  The manual also describes and the setting up of thresholds (in terms of Rain, Sky/Clarity and Light) and the enabling/disabling of the Safe/Unsafe Relay for each element  (It would seem that the Safe/Unsafe Relay probably operates at the lower thresholds (Clear/Cloudy, Dry/Wet, Dark/Light) rather than the higher threshold (Cloudy/V.Cloudy, Wet/V.Wet, Light/V.Light)
   
• The Pulsar Observatories Dome manual and Automation manual (as at 2018) appear to be totally devoid of any information about the Dome Controller's relay facility .  The pop-up help on the Relay settings in the version of the Pulsar Dome Software that originally came with the dome was of little help (and as it turned out the Settings Setup was missing some critical setting options).  
  
  The Pulsar Observatories technician was contacted for assistance, as a result of which I recieved and updated the Dome's software  which gave access to Relay settings that was unavailable with the previous version
   
  • Dome Software & Drivers were updated using the  'Pulsar_Observatories_Package 1.0.32.0.exe'  installer
  • Dome Rotation Driver updated from 1.30 to 1.39
  • Shutter Driver updated from 1.17  to 1.22
     
• The available Relays settings for the Pulsar Dome are shown below along with the associated Pop-Up Help description for each setting.
  
   
  
  It would seem that the best settings to use would be
  
  AutoOpen - Disabled (This is disabled as I would want the opening of  Shutter to be under full control of my Observatory Control Program, operating in either Manual or Automated Mode or under my direct manual control using the Dome Controller panel)
  
  Polarity -    NC or NO   (Best choice to be assessed by experimentation)
  
  Change -  Anytime (Would want protection to always be available, so Dome would close if it started raining whilst Dome was Slewing)
  
  Delay - 10 or 15 Seconds (Ideally I would want the Observatory Control Program to recognise the Rain /Cloud condition and respond accordingly with the Relay acting as a backup protection, but without too much of a delay otherwise the dome interior & equipment could get damaged in a sudden downpour )
   
• A Connector for the Pulsar Dome Relay Port was purchased from RS Components Online (see product page )
  
  The connector is a 2 way/Pole with a clamping-yoke screw system and came as a pack of 5 plugs (the long terminal block shown in the picture on the product picture is misleading)
   
• A 2 wire cable was connected to a Relay Plug with sufficient length to reach Cabinet Bay 1 that contained the Cloud Sensor relay wires and then connected to the Dome Controller.
  It was established that the relay is powered by a 12.8V supply coming from the Dome Controller.
  
      
  
     
  
   
• Two to three hours were spent looking for Relay Settings and Wiring Configurations that gave the required Dome behaviour, whereby  :
  
  - the Dome shutter could open and would stay open when conditions were 'Safe' 
       (according to the criteria that have previously been saved to the Cloud Sensor)
   
  - the Dome shutter could not be opened when conditions were 'Unsafe' 
       (i.e. the opening of the shutter would  automatically abort  before being fully opened and close again)
   
  - the Dome shutter would close when conditions were 'Unsafe'
  
  It was thought that if I use the White (Nornally Closed) wire in the circuit then I would need to use the NC (Normally Closed) Setting in the dome's Relay Settings  (or, if I use the Brown (Normally Open) wire then I would need to use the NO (Normally Open) setting in Relay Settings)
  
  However the opposite proved to be the case and  I ended up using the White (Nornally Closed) wire with the NO (Normally Open) setting in Relay Settings.
  
  It is believed that the discrepency is a difference in terminology. The Cloud Sensor's description of 'Normally Open/Normally Closed' relates to an Active Alert (e.g it is raining), whilst the Pulsar Dome's description of 'Normally Open/Normally Closed'  relates to the absence of an Alert (e.g. it is not raining). This explains why NO Setting works with the NC wire. (Presumably the NC setting would work with the NO wire ?)
  
  
• Happy with the solution found the wiring circuit was then carefully duplicated using a 4-pole terminal block (forming a relay connector) and the functionality again tested.   The wires where then taped up to secure them and the 'relay connector' carefully tucked away beneath the AllSky/Weather cabinet.
  
  Finally the relay cable going to the Dome Controller was inserted into the conduit going to the Dome Controller and then all cables associated with the Controller tidied up as much as possible.
   
    
   
• It should be noted that when working on the Shutter / Shutter Drive it is important to deactivate the relay otherwise the Shutter could shut when one is not expecting it to close.  Of course it should be remembered to reactivate the relay circuit once the work is completed in order to maintain the expected back-up protection.
   
  
• It is important that the Relay Delay value is not set to 0s.   It seems that spurious signals / momentary values when delay setting was 0s led to the shutter instantly and unexpectedly closing even though the sky was completely clear. This might occur up to 5 or so times in a session.  Including a delay (20s or 30s) stops these spurious/unexpected closures and allows Observatory Software to gracefully suspend operations and begin to close the shutter before the relay is activated by the hardware.

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Maintainence and Operational Incidents/Fixes (Jul 2019 - 2022)

Outside Cleaning and Tree Line Trimming (2019-09-03)

Opportunity taken today to some maintainance around the observatory.  

•  Exterior of Dome Observatory cleaned with warm soapy water.
  Using a ladder and the Dome's controls to slew the dome round in 90 deg portions the majority of the roof could be reached and cleaned
  (inspiration and encouragment for this task came from recent Sky At Night article  "How to clean your astronomy observatory" by Steve Richards (no relation), who looks at the cleaning of his Pulsar Dome observatory)
• Northern hedge line and a garden tree were trimmed
• A temporary light shield was installed to block bright light getting to AllSky Camera from a bright security light at nearby building site.

Observatory Exterior getting a good cleaning with warm soapy water & sponge		Northern hedge line trimmed so that it doesn't obscure northern sky from aurora monitoring AllSky Camera
Temporary 'shield' to block an annoying bright worksite security light		Garden Tree trimmed so that it doesn't obscure southern sky from low Declination targets

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Flooded Observatory Floor (2019-10-18)

There was a very heavy rain storm on the morning of 2019-10-18. It was the sort of deluge that overflows the gutters and lifts the drain covers (not literally, but the water was forcing its way out of the drain cover sides and 'boiling' 5cm into the air !). During a visit to the observatory the following day, it was noticed that there was a distinct feeling and sound of water squelching under the rubber floor tiles, and there was water coming up through the gaps between the tiles when pressure was applied.

Pulling back the floor tiles and investigating revealed a huge puddle on water on the floor of the observatory, both on top of and under the plastic membrane. 

Pictures of the Puddle on Observatory Floor following deluge on 2019-10-18

 The rubber floor tiles were lifted and removed and towels used to soak up the large puddle of water. 

After the puddle was cleared an investigation began into how the water got into the observatory: 

•  there was no absolutely no indication that the water had come through the roof, walls or door of the observatory
  • the inside surface of roof and walls were all dry
  • there were no splashes or water on top of equipment etc
  •  the top surface of the rubber floor mat was initially dry when first entered, except for water along the jins between some of the tiles
  •  the carpet floor mat just inside the observatory door was dry.
     
• the water could therefore only have come from below the floor or from under the walls.
  
• water influx via the pier bolt holes (athough an initial canidate) was ruled out
  •  after drying there was no continuing any seep of water from around pier base, but there was water still evident under roof walls.
• water influx coming up through the concrete floor (athough an initial canidate) was ruled out
  •  although the central part of the floor remained much more damp that around the edges which looked relatively dry; this was due to the fact that concrete floor sealant was only put down around the outside and under wall parts of the concrete pad.
    (water had seeped into the floor from the puddle above, rather than had infused upwards from the underlying water table)
• water influx coming under the walls of the observatory is the most-likely point of entry
  •  at least 3 points of obvious weakness in the sealant around observatory wall was noticed
  • one was a small hole in the concrete that corresponded to an aborted drill hole when installing bolts for the fixing the dome to the concrete pad, its about 1.5cm deep and may have allowed water to get under the wall, and corresponds to a damp patch on the floor on the inside
  • two were a line of weakness in the sealent, either a line of weakness between sealent and bottom of dome roof or line of weakness between the sealent and the concrete pad.
  • water continued to seep through from under walls for 3 weeks following initial remedial fix to the sealent around base of outside wall
• water influx coming up the bolt hole used for pinning the observatory to the concrete pad couldn't be ruled out, but is less favoured
  • water that appeared to be seeping from under the observatory floors could have equally been coming up from the bolt holes
  • however its not thought that any of the bolt hole was drilled deeper than the thickness of the concrete pad,
  • if one of the holes had breached the pad its doesn't explain why water appeared to be seeping from mutiple places along the wall base.

Investigating how the water got into the observatory (2019-10-19 & 2019-10-20)

First Repair Attempt
An emergency repair was made a few days later in which the sealent was replaced along all the sections of observatory based with obvious weakness. However this remedial repair was unsuccessful and water continued to seep under the walls from multiple points.

It was concluded that the repair had failed and during a second remedial repair on 2019-11-18, it was evident that the sealent in the first repair attempt has failed to bond to the concrete, during to dampness in the concrete and the seep of built up water still lingering under the wall.

Sealent along observatory base was eventually fixed by a second repair fix on 2019-11-18

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Detached Rubber Trim (2019-10-24)

At some point during the session on night 2019-10-24 the Reinforced rubber edge trim that normally sits around the dome flange edge became detached and then proceeded to peel itself off as the dome rotated. This was only noticed when the observatory was visited the next morning. No damage seems to have been done apart from some abrasion to the rubber strip as it was forced through one of the metal roof retaining clamps.  It is assumed that the incident happened at 03:14 when one particular slew (to GCVS GK Per) took an anomalously long time taking 6.9 mins to complete a 137deg  azimuthal slew (i.e. a speed of only 20 deg/min). 

The rubber strip was re-fitted to the flange taking care to press the reinforcement tighter in order to make it fit tighter to the dome flange especially at the the two ends.  I think this is the second time that this has happened.

Pictures showing the Reinforced Rubber Trim that had detached from dome roof flange during previous night's session
Re-securing Rubber Trim with Pair of Pliers (later picture)

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Cable Conduit Fixing for Dome Controller Leads (2019-11-17)

The original cable conduit for power and USB leads going up to the dome controller, which relied on its sticky tape backing, detached from the observatory wall almost straight after fitting.  Attempts since them to seal the cable house to the wall haven't worked for more than a few days at a time.  Finally a firmer way of attaching the cable housing in place was developed using a pieces of suitable sized wood, held in place by one of the existing bolts that attach the AllSky/Weather Bay to the Observatory.   The cable conduit is now finally held in place in a way that won't come loose..

Pictures showing the new firm attachment for the cable conduit going to dome controller

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Repair to Observatory Base Sealent (2019-11-18)

Following entry of water into observatory during a deluge on 2019-10-18 and a failed first (emergency) attempt at fixing the sealent around the base of the observatory, a second attempt to repair the seal was made a month later on 2019-11-17 / 2019-11-18. It was not easy to find a time to do this in November in November (5 degC 90%+ humidity) when there is a lot of rain and everything remains damp for days on end.   However eventually there there was a brief weather window. After stripping out the old sealant , some 24 hours was spent drying out the concrete pad/under wall area.  After using tissues to absorb the last bits of water from under the wall and a hair dryer to remove the remaining moisture a fresh bead of sealent was finally applied.  This time (hopefully) the repair has done the job. At the least first indications (2019-11-20) are that the leak path has been fixed.

Second Repair Effort  (2019-11-18)
Observatory Floor (2019-11-20) No indication of any residual water seep along walls

Follow Up Note (June 2020)
A few months further on (early 2020) water was again found seeping in from under the walls. 

The plastic membrane has been removed and the floor tiles relaid directly on concrete floor as the membrane was stopping the drying out of the water in warm weather.  A new attempt to seal the walls was made during a dry spell in summer 2020.  

Follow Up Note (November 2021)
Water has again been seeping in from under the walls.  This time new sealant was applied on top of existing sealant and for first time sealant was applied on the inside joint.  See Repair to Observatory Wall Seals (2021-11-08).

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Drainage Holes for Condensation Puddles (2019-11-18)

After a full night of observing with the shutter open all night a considerable amount of dew can build up on the inside surfaces of the dome and its shutter.  Much of this condensation eventually runs down the inside faces of the dome and accumulates on the flat inside rim particularly in the wide area beneath the shutter and on its counter part on the opposite side of the dome.  If the amount of condensation isn't too much it doesn't cause a problem and it eventually evaporates away over the course of several hours (though not without keeping observatory humidity levels high during the process). If there is a lot of condensation the rim puddles can overflow to become floor puddles. Typically the puddle from the beneath the shutter ends up on the floor by the door since the closed shutter intentionally lies over the door when the dome is parked.

Fed up with this situation a number of small holes where made at the backs of the 2 widest areas of the roof rim that will hopefully allow the water of condensation to drain to the exterior of the observatory and reduce the problem inside.

Condensation Puddles on Dome Flange Rim and on Floor
Drainage holes drilled to help allow condensation puddles to drain to exterior

Update 2019-12-18

After a full night of observing on 2019-12-17 with the shutter open all night and temperatures down to -3°C a fair amount of frost built up on the inside surfaces of the dome and shutter.  As this frost melted the next morning lines of of water ran down the inside faces of the dome. Previously this water would accumulate on the flat inside rim particularly in the wide area beneath the shutter and on its counter part on the opposite side of the dome and eventually drip down onto the floor.  But since the drilling of a series of drainage holes at the backs of the 2 widest areas of the roof rim last month the water can now gradually drain to the exterior.

Lines of melt water from the frost that built-up during the previous night's observing session which had experienced temperatures down to -3°C
Drainage holes showing water draining to exterior  (later pictures)

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Fix to Limit Bracket to increase reliability of Shutter Operations (2020-12-18)

During an observing session on 2020-12-17 the shutter was unable to close when clouds developed due to mechanical failure of shutter pulley chain system.   Dome left open to potential damage from rain.  Shutter opened at 18:24. All logs/reports indicate the shutter had successfully opened (no indication at this time of any problem). Autofocusing conducted and 1st target successfully acquired. After clouds developed at 19:06 the Shutter was automatically commanded to close. An alert was issued saying dome hadn’t closed after 100s (normally takes 45-50s to close). 10 minutes later remote monitoring showed that the dome shutter was still in the 'Closing' state and hadn’t reached the ‘Closed’ state.

After spending a couple of minutes to rule out a problem with the DeviceHub connection, the observatory was visited to check what had happened, where it was found that the shutter drive was still busy turning, but the plastic drive chain had 'delinked' and was no longer attached to the drive cog. The shutter was completely open. In fact the shutter was in a position that was 'over-open' such the U shaped metal limit block (bracket) on the shutter and the chain fixture had been driven beyond their normal range and had overridden the rear roof line ,causing the shutter to be loosely stuck. The chain had come apart adjacent to the point of fixture of the chain to the shutter roof. The shutter was manually closed at 19:26 and a user intervention made to close the session (including parking dome and telescope). The issue was deemed critical as automated operations were unable to close the open shutter and observatory equipment would probably have been damaged by a rain shower that occurred later in the evening at 23:00.

An investigation was made the following day. Although the shutter has never done this before (multiple open/close operations over last 2.1/2 years) it was evident with hindsight that this was in fact a problem waiting to happen. It is noted that the height of the limit block compared to the gap between the shutter and the roofline means that the limit switch grazes the rounded end of the limit block rather than hitting the end of the limit block square on.   One link from the chain was missing and couldn't be found. 

It would seem upon opening the dome, the limit switch has been triggered and the message passed on to dome controller and dome driver, but in this particular case the rounded end of the limit block had immediately slipped over the limit switch and over-rode the roofline, causing the shutter to become effectively ‘stuck’. It is supposed that when the command was made to close the dome the chain delinked due to a combination of the very angle at which the chain rubbed on the roofline and the excess force required to pull the shutter back from its ‘stuck’ position.   Alternatively the chain had delinked when it hit the roofline when the shutter overran it normal range upon opening.

A repair was made to the chain by replacing a section of the chain with some spare chain left over from the original installation

A wood insert was used to raise the height of the limit bracket by 8mm in order to prevent the issue from ever occuring again. 

It was subsequently learned that Pulsar Observatories space out the limit bracket with an M8 nut during their own installations, which confirms the fix I had made, but as of 2020-12-21 the Assembly Manual for Pulsar Dome with Drives on Pulsar Website was still showing the limit bracket without the necessary space-out.

Photo showing position of break in shutter chain.		Photo showing Shutter's Normal Open Position Arrows indicating how shutter was driven beyond its normal position
Photo showing Roof Line and position of Upper Limit Switch and Upper Pulley		Photo showing new position of Limit Block (Bracket) when Shutter is Open (limit switch now hits the  side of the Limit Block rather than its rounded top)
Photo showing original position of Limit Block (bracket lies flush with shutter and only grazes the upper limit switch)		Photo showing new position of Limit Block (Bracket) (bracket raised using an 8mm thick piece of plywood so that the limit block can hit the upper limit switch square on) (alternative fix would have been to space out the bracket with an M8 nut)

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Replacement Home Magnet (2020-12-26)

A new replacememt Home Magnet for Observatory Dome was received from Pulsar Observatories.   This was a replacement for the original magnet that had become badly corroded and became unreliable for homing the observatory (photo below left).  The original had a cut or flaw in its outer casing and water had entered the magnet and corroded it over the course of a couple of years. The new magnet (photo below right).was installed and successfully used for an overdue recalibration of the dome. The new magnet also allowed ASCOM Conform tests for the Dome to pass its Find Home Test where it had previously failed.

Photo showing the old corroded magnet		Photo showing the new replacement Home Magnet

Update 2021-12-05
New magnet has also begun to corrode on one side. See image below, casing has fragmented.  The Magnet's magnetic strength seems to be still ok.

Photo showing the new magnet after 12 months

The Magnet Supplied by Pulsar is a 10mm diameter x 5mm thick, very strong Neodymium magnet,  like these ones from Amazon :
 F645-N52-10 Magnet Expert 10mm dia x 5mm thick Ultra High Performance N52 Neodymium Magnet - 3.2kg pull ( Pack of 10 ) by first4magnets™
 https://www.amazon.co.uk/Magnet-Expert-thick-Performance-Neodymium/dp/B00GFMQ5OM   (£10.48)

- Corrosion issue is due to basic rusting process (metal/Fe + water + oxygen). 
- The magnet is inevitably exposed to water from dew/condensation created during nightime observing sessions.
- Neodymium magnets are apparently known for their poor resistance to corrosion, unless they are waterproof versions that are coated by a plastic layer or shrink-wrapped in a PVC cover (which the Pulsar supplied magnets are not)
- The position that the Home magnet needs to be placed in my system, where it sits in direct contact with metal embedded in the reinforced rubber trim, might enhance the rate of corrosion either directly by some electrolysis effect or by causing damage/scratching to the magnet's 'protective' casing.
- Based on original supplied magnet, the corrosion will eventually progress to the point that it is no longer strong enough to be detected by the Dome Unit/Encoder.

Update Q2 2022.
A pack of ten 10mm diameter cylindrical magnets have been purchased quite cheaply via Amazon for £3.95, and are intended to provide a backup in case of a future failure of existing magnet.  They're only 3mm thick and only have only 1.2kg pull.  Future testing is required to see if they have sufficiently strength or not.

Update 2022-07-13
The dome's current Pulsar Supplied home magnet (5mm) was checked today (2022-07-13) and whilst it has continued to corrode it still works ok for finding the dome's Home position. 

It is likely however that future corrosion will eventually reduce its magnetic strength to the point that it will now longer be detected by the dome controller/magnetic reciever, and demands that a working backup is available on standby.

Tests show that one of the 10mm dia by 3 mm width regular magnets (purchased earlier this year) doesn't t have sufficient strength to be detected as a home magnet. However it was found that two of these magnets used together does have sufficient strength, and can provide a working backup option.  It is possible, but not yet proven, that two regular magnets will have better corrosion resistance than the Pulsar Supplied Neodymium magnet.   See Home Magnet Tests (2022-07-13)

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Shutter opening issue (2021-01-08)

OpenShutter request at 06:26 failed after 37s with ShutterStatus=5 (Error), whilst a followup OpenShutter request at  06:29 failed after 10s with ShutterStatus=5 (Error).   Dome Open/Closing was tested the following day in daylight conditions.  The shutter opened ok but the stutters as the shutter/chain connector jumps over the pulley wheels were again very noticeable (as they usually are).  Examining the higher guide wheel shown that it has a slight notch worn it to it where the screw head on the shutter/chain connector hits the wheel.  It is theorised that the resistance at the guide wheel points, cold temperature and ice combined to cause shutter opening to stall and produce the Shutterstatus=5 (Error).   It is assumed that the stall after 37 sec corresponded with the upper guide wheel, whilst the later stall after 10 sec corresponded with lowermost wheel.  The higher pulley wheel was rotated to offer a fresh surface for the chain and the Shutter/Chain Connector spacing was adjusted in an attempt to reduce the resistance of the connector coming over the wheels, but there didn't seem to be any improvement.       

Pulsar Observatories were contacted for advice (response pending).

Photo showing shutter chain passing over upper guide wheel		Photo showing chain/shutter connector passing over upper guide wheel

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Shutter Chain Adjustments (2021-01-15)

Following an issue with shutter opening in Session S847 (2021-01-08)  (opening failed after 10-27s with ShutterStatus Error=5  and opening stutters/jumps awkwardly when chain bolt goes over guide wheels) and some advice from Pulsar Observations, a couple for adjustments were made to the Observatory's Shutter Chain today (2021-01-15).

• Spacing on Chain Bolt has been reduced in order to provide more clearance when head of chain bolt passes over guide wheels.  One of the two spacer nuts that were present on the 6mm chain bolt, has been taken out and replaced with a couple of washers, so that there is effectively 1.1/2” nuts worth of spacing instead of 2. With the chain attached closer to the shutter, the head of the chain bolt is now ‘lifted’ over the guide wheels as the shutter opens/closes, but is not too close that the chain is too far distorted when the shutter is at its limits and the chain is drawn against either the upper roof line and lower bottom line.
  
  With just 1 nut worth of spacing the chain gets too distorted (too bent) when it is at either limit and I was previously worried about it potentially causing the chain to delink. With 3 nuts worth of spacing there is potential for the shutter to bind on the guide wheel brackets.
   
• Chain has been tightened in order to remove the previous slack.  This was accomplished by taking out one link in the chain.
  
  When I tried with one less link during dome's original installation I found things were too tight and had to put link back in.  And since then have lived with the chain being on the slack side (slack even with the shutter drive positioned to apply maximum tension on the chain). That I can now go with one less link makes me think that the chain has either slightly ‘lengthened’ with 2.1/2 years use or my realignment of the shutter drive unit in late 2018 reduced the required chain path length just enough. Certainly the slack in chain has now all gone.
  

Photo showing previous chain bolt spacing (2 nuts + 1 washer) (photo taken 2021-01-09)		Photo showing new reduced chain bolt spacing (1 nut + 3 washers) (photo taken 2021-01-15)
Photo showing previous slack  in shutter chain (photo taken 2021-01-09)		Photo showing shutter chain post-tightening (slack removed by taking out one link in chain) (photo taken 2021-01-15)
Photo showing upper pulley wheel with tightened chain and reduced chain bolt spacing (photo taken 2021-01-15)		Photo showing shutter chain after tightening (photo taken 2021-01-15)

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Repair to Observatory Wall Seals (2021-11-08)

Description
With a large amount of rain over the period 2021-10-28 to 2021-11-01 (see chart below), the observatory floor became increasing wet and began to rise up through the joints in the rubber floor matting.   The water seeps in under the walls at places where the white sealant has degraded.


Note:  Y Axis is 'rain rate' as measured by Eurotech/Aurora Cloud Sensor

This has been on ongoing issue since observatory was constructed in 2018 (see Flooded Observatory Floor 2019-10-18), and the seal has been changed out on 2 previous occasions (see Repair to Observatory Base Sealent 2019-11-18).  A certain amount of water under the matting can be tolerated but the amount finally become too much and a new repair was required.

Fix
Floor matts have been removed (2021-11-01) and the excess water removed with towelling.  Floor was allowed to dry out and some emergency No-Nonsense All Weather Sealant applied as a strip on the outside and (for first time) inside the wall base in an fresh attempt to try to stop further water ingress. The sealant is supposedly ''suitable to use in wet weather conditions".  Seals were applied today (2021-11-08).   Floor matts were relaid (2021-11-11)  after giving the inside seal opportunity to set.

In past fixes (2019 and 2020) the old seal has been pulled out before applying new sealant, but since this hasn't proved to be a long term fix in the past, this time the outside sealant has been applied on top of existing sealant.    Photos below showing the new sealant in place.

Photo showing sealant applied on outside joint between dome wall and concrete base (sealant has been applied over the top of existing seal)		Photo showing sealant applied on inside joint between dome wall and concrete base (this is first time that sealant has been used on inside)

Update 2021-12-08
Whilst the observatory floor has stayed dry for the past 4 weeks following attempted wall seal fix, it was found to be again wet this morning following the heavy deluge that we had from Storm Barra last night (2021-12-07). Not as bad as before, water under floor matts over only 1/3 of the floor area and hadn't risen up through the joints. between tiles.   Matts removed from affected areas and water soaked up with a sponge.   Will apply some further sealant during the next dry spell

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Shutter failed to fully close, hold up on bottom aperture lip (2021-11-10)

Observatory Shutter failed to fully close during an automated observing session on 2021-11-09 and was investigated the following day.   Dome was commanded to close when conditons deteriorated, but checking observatory status 20 minutes later indicated that Shutter was still in the Closing State.  A trip out to the Observatory showed that the lower lip of the Shutter was hung up on the rubber strip that sits on the lower edge of the aperture leaving the shutter almost closed but still around 2cm from its fully shut position.  

The Shutter drive unit motor had turned itself off, there were no growling noises coming from it at least (this is good and answers a long standing question about what happens if the shutter hangs up).  Under manual control the shutter was partially opened using the red button on the Shutter Drive Unit and then pulling the lower aperture inwards  by hand the shutter was finally closed (again using the red button).

Investigating it is clear that the primary cause of the failure was that the roof panel below the aperture, to which the shutter drive is attached, bows out. There is a 1.5cm of play in the panel and it supposed that the shutter just happened to hang up on this occasion.  It has been this way still its original construction and erection of the observatory in 2018 , but it hasn't presented a problem before now .   The dome roof was constructed on a flat surface and at the time it didn't seem that the 4 four quadrants would fit together without the bulge appearing and still keep the surfaces of the four quadrants smooth where they abutted.

Day time pictures that try to illustrate the failure the previous night are shown below.

Photo showing shutter and roof paneling below lower aperture Dome is at 158° Az position		Photo showing bulge in roof paneling below lower aperture This is with the shutter in its fully closed position
Photo showing shutter and lower aperture lip This is with the shutter in the hung up posituon in a reconstruction of the failure the previous night		Photo showing rubber strip on lower aperture lip This has now been removed to reduce the  probability of a future failure

A rubber strip is attached to the bottom lip of the aperture.  This does make the lip wider than it would be without it,  but even with this rubber strip the shutter has previously always managed to ride over the bottom aperture lip and fully close.

Re-reading the Installation manual I see that it does say  "Note that domes with shutter drives do not have the rubber strip"  but I had sufficient length of rubber strip supplied with the observatory and I used a piece of it on the lower aperture lip without any problem up to now. I just had to cut out an appropriate region at the point where the limit switch is positioned.   The manual shows pictures in the Dome Drive section both with and without this rubber strip being present.

With hindsight this was probably a problem just waiting to happen, but there may be two contributing factors to trigger it on this occasion

• The dome and its shutter got a significant buffeting from 50-60mph gale force winds last week which may or may not altered the roof or shutter in some subtle way.
   
• The dome was orientated to Az 158° which might be at a position where the bottom aperture lip happens to be pushed out a bit further than other positions

Fix/Workaround
I considered various means for either stopping the aperture lip/panel from bulging outwards so far or would keep the shutter further away from the lip but couldn't think of anything that would work (see more detailed notes).  It was decided that the best way of resolving the issue (or at least minimising the risk of it happening again) was to remove the rubber strip from the aperture. This was done today (2021-11-10). 

Daytime tests (2021-11-11) indicate that the fix works and observatory operations can continue. The potential of a future hang up is still there since the root cause hasn't been dealt with.  Dome closing operations will be therefore be monitored closely over the next two or three sessions to allow confidence in the shutter system to be regained.

Update 2021-12-05

An attempt was made to see if the panel below the lower aperture could be 're-trained' to stay in its correct 'non-bulged' state. A bungee cord was used to pull the panel inwards whilst gentle heat was applied to the panel with a hair-dryer and then left to cool down.  The tie was left in place for about one hour. It may or may not have made a slight improvement.   The cord was removed after an hour since an observing session was to take place that evening, and the tie cannot be left in place whilst the dome rotates in azimuth.   Although it is doubtful that the 'training' will work, further and longer attempts to 'train' the panel will be made over the next few weeks.

Photo showing bulge in roof paneling below lower aperture This is with shutter in its fully closed position		Photo showing roof paneling with it pulled in by bungee cord (bulge is pulled in but returns again when elastic cord is removed)
Photo showing bungee cord being used to pull-in the bulge in the roof panel (this is in an attempt to retrain the panel to remove the buldge that caused the shutter to hang up)		Photo showing bungee cord connecting roof panel and telescope pier/wedge (obviously the tie can't be left in place whilst the Observatory is operational since the dome needs to rotate)

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ASCOM Driver Review (2022-07-02)

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Home Magnet Tests (2022-07-13)

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Dome Cleaning (2022-11-04)

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Snow slid off Shutter onto Scope (2023-01-16)

During session on 2023-01-16, the shutter was closed and the session suspended ahead of cloud with frequent snow showers. Two hours after the showers had ended (having dropped around 2cm of snow) and after the skies had cleared of cloud the dome was reopened and the session continued with the acquisition of images from 8 further targets.   When those images were quickly examined in the morning it was discoved that whilst they contained stars the background had a very uneven illumination pattern. Investigation showed that images appeared this way because of snow / ice on parts of the front lens of the LX200 scope.  There was also some snow/ice on front part of the fork, on the left hand fork arm and on two small regions of the observatory floor located either side of the scope.  The distribution of ice and the fact that the observatory was closed during the snow showers, strongly suggest that some of the snow/ice that had accumulated on the shutter has slipped and fell into the Observatory when the shutter was opened.   Unfortunately the telescope was pointing in a fairly upward direction at the time (pointing to altitude 58°) and some of the snow/ice fell into the dew shield and onto the LX200's corrector lens. 

The snow/ice was cleared away from the front of the scope in the morning and dried out.  Other snow/ice on the telescope and floor were was collected with brush and pan (before it had a chance to thaw),  and removed from observatory.

Whilst the risk of snow/ice entry during shutter opening after snowfall is a known risk,  the mitigation of pointing the telescope in a horizontal direction wasn't actioned on this occasion  (I had just woken up from an alarm I had deliberatlly set and I was too sleepy at the time to think through the operation / risks).   Whilst putting the telescope into horizontal position wouldn't have prevented the snow/ice slipping into the observatory, the dew shield would have stopped that snow/ice getting onto the front of the telescope optics and would thus allowed the remainder of the imaging session to have been successful rather than a failure.

After battling with continued condensatiion issues despite several attempts to clear the condensation / humidity from telescope and several sessions with degraded imaging a Lymax SCT cooler was eventually purchased and used to finally clear the condensation / humidity on 2023-02-09.  This was successful (see Notes : Lymax SCT Cooler, 2023-02-09).

Raw Image showing anomalous illumumination / background		Raw Image showing anomalous illumunination / background
Photo showing snow /ice on front of telescope optics		Photo showing snow/ice on front of fork and balance weights
Photo showing snow/ice on left hand fork arm		Photo showing snow/ice on  floor of observatory (either side of scope)
Observatory Picture/Dashboard at time of incident
Lymax SCT Cooler (2023-02-09)		Lymax SCT Cooler inserted into Visual Back of LX200 Scope(2023-02-09) SCT Cooler successfully used to push humid air out of telescope tube

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