David's Astronomy Pages Notes - New Observatory Plan (2018)

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	New Observatory (2018)
	- Justification and Aims for New Observatory
	Outline Plan
	Outline Project
	Potential Issues
	Electrical and Connectivity Requirements
	Images from 2017-12-13 >>

New Observatory (2018)

After using my roof-off roof observatory for some 21 years (used at 3 different sites) and struggling with it in the past couple of years I've decided that I need to get a completely new observatory in 2018.   The plan is to get a 2.2m dome observatory with rotation and shutter drives, but is still subject to spousal permission / negiotiation.

Mock-Up View of New Observatory

Justification and aims for the New Observatory are listed below.

Justification and Aims for New Observatory

1) Resolve 5 specific issues associated with my current 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 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 20 year old shed frame

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

  - increase astronomical observing/imaging time, by being easier to operate and 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   (at present 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)

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

 - provide a robust weather resistant structure requiring less maintainence.

  3) Help meet specific future observing plans

 - exoplanet transits

  - high resolution planetary imaging

  - solar observing

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Outline Plan

The outline plan for the new Dome Observatory is to site it in approximately the same location as the existing Roll-Off Roof Observatory, but offset it slightly to allow for a new pier base and to position it slightly further from boundary fencing.  I expect to reuse the existing Power Supply Line.    A plan view illustration is shown below (Note that precise offset from existing observatory, precise southerly pier offset from dome centre and the positions of the observatory door and a planned single bay are still to be finalised).

Outline Plan for New Observatory

Plan is to buy a 2.2m Full Height Dome Observatory from Pulsar Observatories ( https://www.pulsarastro.com/ ) including key accessories such as Rotation and Shutter Drives.

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Outline Project

Outline project plan is as follows:

- Agreement to proceed
- Order 2.2m dome observatory from Pulsar Observatories for delivery in spring 2018
- Consult Electrician regarding observatory power supply & power panel for new observatory.
- Remove existing observatory (including removal of roll-off supports & metal pier)
- Reduce the height of current metal pier (contract local metal fabricator/blacksmith)
- Dig hole for new pier base and footings for the observatory's concrete pad
- Build and install levelled wooden former for pier base/concrete pad
- Fill wooden former with concrete and level off concrete (contract local concrete supply & delivery firm)
- Receive dome observatory and self install (with help from son)
- Drill holes in Concrete Pier Base, Install Bolts and Install pier
- Install power panel & hook up (contract Electrician where required)

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Potential Issues

	Pier Block (Old concrete pier block may cause physical problems during the construction of a new pier block)
	GPS Fix (LX200 may be unable to get GPS fix (including accurate time) at start up 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 dome observatory with deterimental imapct on equipment etc)
	Power Overloading (Power requirements including new equipment might exceed 13A fuse rating on the main plug serving the observatory)

1) 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)

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.

2) 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)

3) 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)
- 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.

4) 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.  
- If required,  purchase a de-humidifier to reduce humidity & prevent condensation
  (Humidifier will require the following features:   Desiccant dehumidifier,  Continuous drain facility , Humidistat)

5) 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)

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Electrical and Connectivity Requirements

			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.

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