David's Astronomy Pages
Notes - Session 728 (2019-12-10)

 
Bullet Session Aims & Highlights
 - Observing Result
 - Night Summary Plot
 - Session Event Log
 
Bullet Operational Issues
  - Critical Issues (0),  Major Issues (0),  Minor Issues (6),  Continuous Improvement (2)
   
Bullet Polar Alignment - Measurements and Adjustments
Bullet Declination Backlash - Measurements
Bullet PHD2 Update to v2.6.6.dev3
Bullet Images from 2019-12-10  >>
 
2019-12-11
Bullet 2" Field Flattener (TSFLAT2)
Bullet LX200 Declination Drive Checks (1)
Bullet LX200 Re-Balancing (1)
 
2019-12-14
Bullet LX200 Re-Balancing (2)
Bullet LX200 Declination Drive Checks (2)
Bullet Polar Alignment Checks
 

Session Aims & Highlights (2019-12-10)

Main aims

  1. Polar Alignment:  Use PHD2 Drift Align Tool to improve polar alignment and thus improve autoguiding performance.
  2. Targets: Acquire images of a selection of targets under moonlit sky conditions including variable stars, nearby stars and comets.

Equipment & Software

Highlights

Lowlights

Summary Plots & Logs

Observing Plan
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Observing Result
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Slew/Centering Performance
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Dome Slewing Performance
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Sky Conditions (Locate Frames)
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Night Sky Summary Plot
Top axis: Sky Brightness at Zenith (in ADU/s)
Lefthand axis: Local Time (hh LT). Righthand axis: Sun Altitude (degs)
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Pre-Session Weather Forecast (API data from darksky.net)
Forecast showed initially cloudy clear with some rain, but then clearing after midnight. Wind quite strong
In the event skies rain stopped at 17:00 and skies at 20:00
Observatory opened at 22:07 and Polar Alignment, BackLash Testing was conducted.
Main session was started at 02:20 and continued until 05:37 when session suspended
due to passing cloud and overall reducing star count.
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Session Event Log
Time     Event Detail
21:54:26 Session Created Live Session Created (2019-12-10 S00728, ImageSaveNum: 728001)
21:54:38   Scope Switched On Scope Power has been switched on via UPB Powerbox.
21:55:44   Services Stopped Observatory Services stopped
21:55:48 Program Closed Program closed by User
22:04:16 Session Resumed Live Session Resumed (2019-12-10 S00728, ImageSaveNum: 728001)
22:06:25   Obs.Manager Started Obs.Manager started
22:06:27   Obs.Overseer Started Obs.Overseer started
22:06:31   Services Started Observatory Services started
22:07:45   Shutter Opened Shutter opened (opening time 44s)
22:09:44   Telescope Connected Telescope Connected (TheSky6)
22:10:05   Camera1 Connected SBIG Camera Connected (set point -20°C)
02:03:56   Services Stopped Observatory Services stopped
02:04:05 Program Closed Program closed by User
02:05:15 Session Resumed Live Session Resumed (2019-12-10 S00728, ImageSaveNum: 728001)
02:06:24   Obs.Manager Started Obs.Manager started
02:06:26   Obs.Overseer Started Obs.Overseer started
02:06:30   Services Started Observatory Services started
02:06:43       Focusing Started Foc2 Focusing Started (Secondary Scope, using ShCap)
02:08:03       Focusing Failed Foc2 Focusing Failed - star lost
02:08:08   Telescope Connected Telescope Connected (TheSky6)
02:08:23   Camera1 Connected SBIG Camera Connected (set point -20°C)
02:10:17       Focusing Started Foc2 Focusing Started (Secondary Scope)
02:13:50       Focusing Completed Foc2 AutoFocus Completed (Profile No 2)
02:14:36       Focusing Started Foc2 Focusing Started (Secondary Scope, using ShCap)
02:16:34       Focusing Completed Foc2 AutoFocus Completed (Profile No 3)
02:17:55 Observatory (Auto) Observatory placed in Fully-Automated Mode
02:17:58 Session Pending Session pending (2019-12-10)
02:18:00 Session Initiating Session initiating (2019-12-10)
02:18:02   Plan Requested Observing Plan requested from AstroPlan (1.13.6)
02:18:21   Plan Loaded Observing Plan loaded to queue (2019-12-10 V1 BEST PLAN, Plan ID: 431)
02:18:24   Camera1 Connected SBIG Camera Connected (set point -20°C)
02:18:29   Telescope Connected Telescope Connected (TheSky6)
02:18:42 Session Equilibration Session ready for dome & camera equilibration
02:18:45   Equilibration Started Dome Equilibration started
02:18:59   Equilibration Skipped Dome Equilibration skipped by user
02:19:01 Session Running Session running
02:19:03   Queue Started Observing Queue started (26 targets selected)
02:20:56     Target Started (1/26) Target started (1/26, Scholz's Star)
02:23:32       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
02:25:47       Focusing Completed Foc1 AutoFocus Completed (Profile No 4)
02:41:15     Target Completed Target completed (1/26, Scholz's Star)
02:41:53     Target Started (2/26) Target started (2/26, GCVS NV Ori)
02:44:41       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
02:46:30       Focusing Completed Foc1 AutoFocus Completed (Profile No 5)
02:50:00     Target Completed Target completed (2/26, GCVS NV Ori)
02:50:03     Target Started (3/26) Target started (3/26, GCVS FU Ori)
02:51:59       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
02:54:34       Focusing Completed Foc1 AutoFocus Completed (Profile No 6)
02:57:09     Target Completed Target completed (3/26, GCVS FU Ori)
02:57:12     Target Started (4/26) Target started (4/26, GCVS FO Ori)
02:59:10       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
03:00:57       Focusing Completed Foc1 AutoFocus Completed (Profile No 7)
03:04:51     Target Completed Target completed (4/26, GCVS FO Ori)
03:05:14     Target Started (5/26) Target started (5/26, GCVS U Gem)
03:07:51       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
03:09:56       Focusing Completed Foc1 AutoFocus Completed (Profile No 8)
03:13:31     Target Completed Target completed (5/26, GCVS U Gem)
03:14:17     Target Started (6/26) Target started (6/26, GCVS DX Cnc)
03:17:09       Focusing Failed Foc1 Focusing Failed - star is too dim (TCF-S)
03:22:09     Target Completed Target completed (6/26, GCVS DX Cnc)
03:24:09     Target Started (7/26) Target started (7/26, GCVS CN Ori)
03:27:04       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
03:29:49       Focusing Completed Foc1 AutoFocus Completed (Profile No 9)
03:33:16     Target Completed Target completed (7/26, GCVS CN Ori)
03:33:18     Target Started (8/26) Target started (8/26, GCVS RX And)
03:35:51       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
03:37:49       Focusing Completed Foc1 AutoFocus Completed (Profile No 10)
03:40:22     Target Completed Target completed (8/26, GCVS RX And)
03:40:24     Target Started (9/26) Target started (9/26, GCVS DY Per)
03:42:23       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
03:44:19       Focusing Completed Foc1 AutoFocus Completed (Profile No 11)
03:49:18     Target Completed Target completed (9/26, GCVS DY Per)
03:49:20     Target Started (10/26) Target started (10/26, C/2017 T2 (PanStarrs))
03:51:18   SoftSuspend Called Soft Suspend is called due to Deteriorating Conditions (too few stars)
03:51:22   SoftSuspend Cancelled Soft Suspend is cancelled due to Improved Conditions
03:51:24       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
03:53:24       Focusing Completed Foc1 AutoFocus Completed (Profile No 12)
03:55:33   SoftSuspend Called Soft Suspend is called due to Deteriorating Conditions (too few stars)
03:55:38   SoftSuspend Cancelled Soft Suspend is cancelled due to Improved Conditions
04:00:23   SoftSuspend Called Soft Suspend is called due to Deteriorating Conditions (too few stars)
04:00:49   SoftSuspend Cancelled Soft Suspend is cancelled due to Improved Conditions
04:02:02     Target Completed Target completed (10/26, C/2017 T2 (PanStarrs))
04:03:03     Target Started (11/26) Target started (11/26, GCVS RR Tau)
04:04:57       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
04:06:46       Focusing Completed Foc1 AutoFocus Completed (Profile No 13)
04:13:18     Target Completed Target completed (11/26, GCVS RR Tau)
04:13:37     Target Started (12/26) Target started (12/26, GCVS SU Tau)
04:15:42       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
04:17:34       Focusing Completed Foc1 AutoFocus Completed (Profile No 14)
04:22:17     Target Completed Target completed (12/26, GCVS SU Tau)
04:22:43     Target Started (13/26) Target started (13/26, GCVS ER UMa)
04:25:54       Focusing Failed Foc1 Focusing Failed - star is too dim (TCF-S)
04:29:53     Target Completed Target completed (13/26, GCVS ER UMa)
04:32:31     Target Started (14/26) Target started (14/26, GCVS RZ LMi)
04:35:29       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
04:37:23       Focusing Completed Foc1 AutoFocus Completed (Profile No 15)
04:42:54     Target Completed Target completed (14/26, GCVS RZ LMi)
04:43:49     Target Started (15/26) Target started (15/26, GCVS SY Cnc)
04:45:57       Focusing Failed Foc1 Focusing Failed - star is too dim (TCF-S)
04:49:23     Target Completed Target completed (15/26, GCVS SY Cnc)
04:52:58     Target Started (16/26) Target started (16/26, LAMOST-HVS1)
04:55:20       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
04:58:18       Focusing Completed Foc1 AutoFocus Completed (Profile No 16)
05:01:25     Target Completed Target completed (16/26, LAMOST-HVS1)
05:01:54     Target Started (17/26) Target started (17/26, GCVS GK Per)
05:04:34       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
05:05:35   SoftSuspend Called Soft Suspend is called due to Deteriorating Conditions (too few stars)
05:06:05   SoftSuspend Cancelled Soft Suspend is cancelled due to Improved Conditions
05:06:39       Focusing Completed Foc1 AutoFocus Completed (Profile No 17)
05:09:36     Target Completed Target completed (17/26, GCVS GK Per)
05:09:45     Target Started (18/26) Target started (18/26, GCVS CM Tau)
05:12:04       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
05:14:07       Focusing Completed Foc1 AutoFocus Completed (Profile No 18)
05:28:17     Target Completed Target completed (18/26, GCVS CM Tau)
05:28:47   SoftSuspend Called Soft Suspend is called due to Deteriorating Conditions (too few stars)
05:29:15     Target Started (19/26) Target started (19/26, GCVS AM CVn)
05:32:31       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
05:33:31       Focusing Failed Foc1 Focusing Failed - star lost
05:37:15     Target Completed Target completed (19/26, GCVS AM CVn)
05:37:17   Queue Paused Queue paused for SoftSuspend
05:37:20 Session Suspended Session suspended
05:38:08   Shutter Closed Shutter closed (closing time 50s)
05:47:54     Target Cancelled Target cancelled (20/26, 38P/Stephan-Oterma) due to wind
05:58:34     Target Cancelled Target cancelled (21/26, GCVS U Her) due to wind
06:08:45     Target Cancelled Target cancelled (22/26, GCVS AM Her) due to wind
06:21:49     Target Cancelled Target cancelled (23/26, GCVS S Cyg) due to other condition
06:31:25     Target Cancelled Target cancelled (24/26, GCVS R CrB) due to wind
06:43:42     Target Cancelled Target cancelled (25/26, GCVS CN Leo) due to wind
07:05:16     Target Cancelled Target cancelled (26/26, K2-18) due to wind
07:05:21   Queue Completed Job Queue completed
07:05:25 Session Closing Session closing
07:05:30   Shutter Closed Shutter already closed (closed at 05:38, closing time 50s)
07:05:55   Dome Parked Dome parked (parking time 25s)
07:06:07   Telescope Parked Telescope parked (parking time 11s)
07:06:50 Session Housekeeping Housekeeping Started (Cleanup FITS, Create Fits Summary, Transfer Files)
07:07:03 Session Finished Session Finished
   

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Operational Issues (2019-12-10, S728)

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Critical Issues

Major Issues

Minor Issues

Continuous Improvement

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Polar Alignment - Measurements and Adjustments

PHD2's Drift Align Tool was used at start of session to try to improve polar alignment and thus improve autoguiding performance.
Used images from the ZWO ASI 178MC camera attached to the 80mm GuideScope.  Images are orientated North Up, East Left.

 

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Declination Backlash - Measurements

PHD2's Guiding Assistent was used to measure the LX200 Mount's Declination Backlash at a number of sky points.

These were all done using Guide Speed x0.66 (ie. a guide speed of ~10 arc secs/sec)

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PHD2 Update to v2.6.6.dev3

Latest development version of PHD2  (v2.6.6dev3, dated 2019-12-07) installed onto Observatory and Office Computers

https://openphdguiding.org/development-snapshots/

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2019-12-11


2" Field Flattener (TSFLAT2)

2" Field Flattener and Corrector (TSFLAT2) from TS-Optics (Germany) was installed on the secondary scope today, along with necessary extension tubes to connect to my existing Orion X-Y Star Finder & ZWO ASI 178MC Camera.

(the prime purpose of the flattener/corrector is to obtain high quality off-axis imaging is a setup where the camera sensor is deliberately placed off axis to allow the secondary scope to be perfectly centered on the same FOV as the main scope)

The 2" flattener (TSFLAT2) was purchased instead of the larger 2.5" flattener (TSFLAT2,5) because it was
a) significantly cheaper  ( 179 vs 289 EUR), and is more than adequate for size of the CMOS sensor on my  ASI 178MC camera
c) allow easily swapping in of Herschel Wedge for Solar Imaging (centered in optical field and does require flattener)

My TS 80mm f/6 APO Scope has a 480mm focal length. For focal lengths of  450 to 490mm  the Field Flattener requires 123mm separation distance from the camera sensor for optimal flattening.  (Product Page on Teleskop Express Website). With my 178MC camera and Orion XY Finder have a combined backfocus of 50.5mm, so  I needed 72.5mm of extension tubes. I didn't purchase the TSFLAT2A extension option (where online shop select the items for your setup), but instead selected the extension items myself.

--------------------------------------------------------------------- Back of 2" Field Flattener
  30.0mm    (TSVF230,  30mm Extension tube, 2")
    6.0mm    (TSM48i-T2a,   Adapter,  2" to T2)
  26.0mm    (TST2V26,  26mm  Extension Tube, T2)
  10.0mm    (TST2V10,  10mm Extension Tube, T2)
  38.0mm    (Orion XY GuideStar Finder, T2 to 1.25"
  12.5mm    (ZWO ASI 178MC Camera, 1.25" nose)
--------------------------------------------------------------------- Camera Sensor
122.5mm Total (vs 123mm Required)

The 30mm Extension Tube allows the field flattener to pushed further into the telescope back tube if required or lfor ater optimisation.  As there are no natural stops on the 2" flattener & extension tube a Baader Hyperion 2" parfocal ring was added to allow consistent placement of the assembly within the telescope's focuser. This will assist the swapping in/out with 2" Herschel Wedge for solar viewing, without loosing track of the focus position.

2" Field Flattener and Tube Extensions (loose)
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2" Field Flattener and Tube Extensions (assembled)
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2" Field Flattener, Tube Extensions and Orion XY GuideStar Finder (assembled)
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2" Field Flattener installed on Secondary Scope
(Note : the Orion XY Guidestar Finder is used for centering the
secondary scope's camera on the same FOV as the main scope,
rather than for guidestar finding which is not an issue)
Image


After installing the new TSFlat2 Field Flattener a careful check was made to ensure that the guiding/imaging train was absolutely locked tight and rigid.  Whilst the majority of the train was rigid there was movement of the camera in the Orion XY Guidestar Finder, relative to the T2/2" extension tube & telescope.  This is due to slight play in the XY Guidestar Finder unit associated with the mechanical components that enable the XY Offset. This was resolved by using two small clamps to rigidly hold the two parts of the XY Finder together and take out all the play.

Small clamps added to take out play in Orion XY Guidestar Finder
Image

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LX200 Declination Drive Checks

As part of checking out large and variable Declination Backlash (see Declination Backlash Measurements above) the Declination Drive Cover was removed from the right hand fork arm in order to examine the Declination Drive.  The movement of the Declination Drive Unit and its tension against the large Declination Gear seemed normal.   It would have been nice to a) reduce the travel distance of the drive unit using travel limit screw and b) insert a small washer to increase the spring tension, but it wasn't possible to apply a enough leverage to move the screw using a small hexagonal allen key with risk of breaking the key or stripping the hexagonal slot on the screw.

In the process of loosening and removing the Declination Knob it was noticed that the scope is badly out of balance, which was expected and is the most likely cause of the very the variable declibatiion backlash & associated poor guiding in declination

Declination Drive Knob & Cover Removed
(strapped to the fork arm below the Dec Motor is
Pegasus UPB Powerbox and TCF-S Focuser Controller)
Image
  
Declination Drive Unit Examination
Location of the
Tension Limit Screw is highlighted
Image

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LX200 Re-Balancing (1)

As part of checking out the large and variable Declination Backlash (see above) and associated poor autoguiding performance the Balance of the LX200 Main Scope was re-checked.

(this was done after installing new 2" Field Flattener on secondary scope, see 2" Field Flattener, TSFLAT2)

The LX200 Scope was previously balanced when it was installed in Observatiory in May 2018 so that the OTA tube was balanced with the tube lying horizontal when pointing due south.  This is at a position where scope is pointing at Declination -32°. In practice this is of course never a position where autoguiding/imaging is ever active; for all positions (Dec  -25° to +66°) where autoguiding/imaging is actually employed the scope is out-of-balance (being only moderately balanced for Dec -25° to +10° & very poorly balance for Dec +10° to +66°)

The poor balancing iof the OTA tube was very noticable when the Declination Knob and Cover were removed to check Dec Drive Unit. The OTA 'demands' to point vertical pulled down by the weight of the heavy SBIG Camera/Filter Wheel & TCF-S Focuser.

To improve balance two things were changed
a) the counter weights below the OTA (cylindrical weights plus two lead-weighted ankle exercise weights) were pushed as far forward as they would go.
b) the guidescope was pushed slightly further forward

Checks following the these two changes shows that the OTA is now in balance when scope pointing at Dec 0° (Altitude 32° when pointing due south.    When position horizontal the OTA noew tries to point downwards, when tipped up (Alt 45°) the front of the scope still tries to pull towards zenith but not as badly as before.   This means the scope if now very well balanced when pointing at Dec -10° to +10°, moderately well balanced for  -10° to -30° and +10° to +40° and only poorly balanced for Dec +40° to +66°. This is still not perfect but at least a lot better than before.

The OTA balance will be improved further when the AO-8 adaptive optics unit (no longer needed) is removed from the scope. This will reduce weight at the back of the scope in two ways, directly from removing the 0.6kg unit and indirectly by bringing the heavy SBIG ST-10XE camera closer to the scope

Photo showing the Counter Weights below the OTA pushed as far forward as possible
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Photo showing the TS80 Secondary Scope moved slightly further forward
Photo taken with the scope in its new balanced position,  pointing at Dec 0°
 (altitude +32° when pointing due south)
Image


Forward Plan

- Repeat Backlash Measurements
   Image  >> To be done at next session

- Look at adding further weights below OTA in order to achive improved balance when OTA tube in vertical.  At present the scope is top heavy . Options are i) extra ankle weights and ii) extra weight bar.
   Image  Done 2019-12-14 (see LX200 Rebalancing (2) )

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2019-12-14


LX200 Re-Balancing (2)

As part of checking out the large and variable Declination Backlash (see above) and associated poor autoguiding performance some improvements in telescope balance were achieved by moving the counterweights below the OTA further forward, and moving the piggybacked secondary scope further foward (see LX200 Re-Balancing (1) ).   

Whilst this improved the balance, the OTA was still too top-heavy, especially when the scope was pointed vertical. To get better balance the  3D weight system from my old 8" LX200 Scope was requisitioned.   In order to fit onto the rail on my 12" LX200 Scope the hole on the circular metal cylinder had to be drilled out to 15mm diameter (from ~ 13mm).   The weight system only had one remaining weight and until some additional weights arrive, a leaded ankle/wrist exercise weight was used to provide the necessary weight allowing balance to be achieved with the OTA tube both vertically and horizontally.

Balance with OTA tube vertical still needs a little bit of tuning but this will be done after an upcoming modification to the irmaging train to take out an AO-8 adaptive optics unit.  The latter will reduce the weight at the back of the scope in two ways, directly from removing the 0.6kg unit and indirectly by bringing the heavy SBIG ST-10XE camera closer to the scope


Forward Plan

- Review balance again after removing AO-8 unitpeat Backlash Measurements
   Image  >> Waiting on modification to imaging train

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Declination Backlash - Measurements (2)

PHD2's Guiding Assistent was used to re-measure the LX200 Mount's Declination Backlash at a number of sky points, following re-balancing of the scope (see LX200 Rebalancing (2) )

These were all done using Guide Speed x0.66 (ie. a guide speed of ~10 arc secs/sec) and with anti-backlash (Dec) disabled (i.e. Autostar II setting of 0)

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Polar Alignment - Checks (2019-11-14)

PHD2's Drift Align Tool was used to check polar alignment after adjustments made in last session
(see Polar Alignment - Measurements and Adjustments, 2019-12-10) . 

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