David's Astronomy Pages Notes - Session 729 (2019-12-16)

Notes (S728)

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Notes (S730)

	Session Aims & Highlights
	- Observing Result  - Night Summary Plot  - Session Event Log
	Operational Issues
	- Critical Issues (0),  Major Issues (1),  Minor Issues (2),  Continuous Improvement (0)
	Guiding Calibration (update to 0.90 guiding rate)
	Tracking Rate (reset to sidereal rate)
	Declination Backlash (anti-backlash re-tried)
	Images from 2019-12-16  >>

Session Aims & Highlights (2019-12-16)

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

• 12" LX200 and ST-10XME
• 80mm APO and ZWO ASI 178MC
• CCDApp2, TheSky6, CCDSoft5, PHD2,  POTH Hub
• Pegasus UPB & Motor Focus, TCF-S
• SharpCap 3.2, PHD2  2.6.6dev3
   
• AstroMain 3.18.6 ,  Astroguard 1.2.9,   AstroPlan 1.13.6,  AstroShCap 1.2.10, AstroVOE 1.3.4, UPB 1.4.17  (AstroWeather 1.8.2, AstroAllSky 3.5.1)

Highlights

• PHD2 Drift Align Tool. Drift Measurement and Adjustment using PHD2's Drift Align tool was relatively straightforward / relatively quick to make polar alignment adjustments.

Lowlights

•   Declination Backlash.   Declination Backlash measurements made at a number of sky position using PHD2 Guiding Assistent, with backlash values varying between 2938 and 5076 ms.
   
•   Declination Guiding in one direction only.   Declination Guiding was set in one direction only but gave poor results. North was chosen for the session (compared to South in recent testing) as the declination backlash graphs showed the guide movements were much more reliable in the north direction.  However mount flexure issues mean that in some positions the dominant drift is still north requiring southerly directed guiding. There is not enough information or coding in automated procedures for selecting the appropriate setting before guiding starts,  and therefore Resist Switch with a longer settle time may be the best way to proceed.

Summary Plots & Logs

Observing Plan

Observing Result

Slew/Centering Performance

Dome Slewing Performance

Sky Conditions (Locate Frames)

Night Sky Summary Plot Top axis: Sky Brightness at Zenith (in ADU/s) Lefthand axis: Local Time (hh LT). Righthand axis: Sun Altitude (degs)

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.

Session Event Log

Time     Event Detail 00:11:00 Session Created Live Session Created (2019-12-16 S00729, ImageSaveNum: 729001) 00:11:18   Scope Switched On Scope Power has been switched on via UPB Powerbox. 00:13:35   Services Started Observatory Services started 00:16:06   Telescope Connected Telescope Connected (TheSky6) 00:16:45   Services Started Observatory Services started 00:16:51   Telescope Connected Telescope Connected (TheSky6) 00:20:50   Shutter Opened Shutter opened (opening time 46s) 00:21:59   Camera1 Connected SBIG Camera Connected (set point -20°C) 02:17:47 Observatory (Auto) Observatory placed in Fully-Automated Mode 02:17:49 Session Pending Session pending (2019-12-16) 02:17:51 Session Initiating Session initiating (2019-12-16) 02:17:53   Plan Requested Observing Plan requested from AstroPlan (1.13.6) 02:18:29   Plan Loaded Observing Plan loaded to queue (2019-12-16 V1 BEST PLAN, Plan ID: 432) 02:18:32   Camera1 Connected SBIG Camera Connected (set point -20°C) 02:18:36   Telescope Connected Telescope Connected (TheSky6) 02:18:44 Session Equilibration Session ready for dome & camera equilibration 02:18:47   Equilibration Started Dome Equilibration started 02:18:49   Equilibration Skipped Dome Equilibration skipped by user 02:18:51 Session Running Session running 02:18:53   Queue Started Observing Queue started (25 targets selected) 02:24:43 Session Resumed Live Session Resumed (2019-12-16 S00729, ImageSaveNum: 729008) 02:24:51   Scope Switched Off Scope Power has been switched off via UPB Powerbox. 02:24:59   Scope Switched On Scope Power has been switched on via UPB Powerbox. 02:26:29   Obs.Manager Started Obs.Manager started 02:26:31   Obs.Overseer Started Obs.Overseer started 02:26:36   Services Started Observatory Services started 02:27:24   Telescope Connected Telescope Connected (TheSky6) 02:27:44   Camera1 Connected SBIG Camera Connected (set point -20°C) 02:30:28       Focusing Started Foc2 Focusing Started (Secondary Scope) 02:32:47       Focusing Completed Foc2 AutoFocus Completed (Profile No 1) 02:33:09 Observatory (Auto) Observatory placed in Fully-Automated Mode 02:33:11 Session Pending Session pending (2019-12-16) 02:33:13 Session Initiating Session initiating (2019-12-16) 02:33:15   Plan Loaded Observing Plan loaded to queue (2019-12-16 V1 ACTIVE PLAN S729, Plan ID: 432) 02:33:18   Camera1 Connected SBIG Camera Connected (set point -20°C) 02:33:19   Telescope Connected Telescope Connected (TheSky6) 02:33:33 Session Equilibration Session ready for dome & camera equilibration 02:33:36   Equilibration Started Dome Equilibration started 02:33:38   Equilibration Skipped Dome Equilibration skipped by user 02:33:40 Session Running Session running 02:33:42   Queue Started Observing Queue started (25 targets selected) 02:33:44     Target Started (1/25) Target started (1/25, Scholz's Star) 02:44:59     Target Completed Target partially completed (1/25, Scholz's Star) 02:45:01     Target Started (2/25) Target started (2/25, GCVS U Mon) 02:46:58       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S) 02:48:44       Focusing Completed Foc1 AutoFocus Completed (Profile No 2) 02:55:00     Target Completed Target completed (2/25, GCVS U Mon) 02:55:02     Target Started (3/25) Target started (3/25, GCVS DX Cnc) 02:57:30       Focusing Failed Foc1 Focusing Failed - star is too dim (TCF-S) 03:02:13     Target Completed Target completed (3/25, GCVS DX Cnc) 03:02:15     Target Started (4/25) Target started (4/25, LAMOST-HVS1) 03:05:46       Focusing Failed Foc1 Focusing Failed - unable to find a star (TCF-S) 03:08:51     Target Completed Target completed (4/25, LAMOST-HVS1) 03:10:45     Target Started (5/25) Target started (5/25, C/2017 T2 (PanStarrs)) 03:13:57       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S) 03:16:11       Focusing Completed Foc1 AutoFocus Completed (Profile No 3) 03:24:53     Target Completed Target completed (5/25, C/2017 T2 (PanStarrs)) 03:24:55     Target Started (6/25) Target started (6/25, GCVS RR Tau) 03:25:29   SoftSuspend Called Soft Suspend is called due to Deteriorating Conditions (too few stars) 03:27:06       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S) 03:29:11       Focusing Completed Foc1 AutoFocus Completed (Profile No 4) 03:33:54   SoftSuspend Cancelled Soft Suspend is cancelled due to Improved Conditions 03:35:58     Target Completed Target completed (6/25, GCVS RR Tau) 03:36:00     Target Started (7/25) Target started (7/25, GCVS U Gem) 03:37:25   SoftSuspend Called Soft Suspend is called due to Deteriorating Conditions (too few stars) 03:38:35   SoftSuspend Cancelled Soft Suspend is cancelled due to Improved Conditions 03:39:14       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S) 03:41:25       Focusing Completed Foc1 AutoFocus Completed (Profile No 5) 03:44:57     Target Completed Target completed (7/25, GCVS U Gem) 03:44:59     Target Started (8/25) Target started (8/25, GCVS FO Ori) 03:47:30       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S) 03:51:02       Focusing Failed Foc1 Focusing Failed - failed QC check (Quadratic) 03:54:56     Target Completed Target completed (8/25, GCVS FO Ori) 03:54:58     Target Started (9/25) Target started (9/25, GCVS CM Tau) 03:57:06       Focusing Failed Foc1 Focusing Failed - star is too dim (TCF-S) 03:58:17   SoftSuspend Called Soft Suspend is called due to Deteriorating Conditions (too few stars) 04:05:17   SoftSuspend Cancelled Soft Suspend is cancelled due to Improved Conditions 04:11:17     Target Completed Target completed (9/25, GCVS CM Tau) 04:11:28   SoftSuspend Called Soft Suspend is called due to Deteriorating Conditions (too few stars) 04:11:45     Target Started (10/25) Target started (10/25, GCVS ER UMa) 04:14:32       Focusing Failed Foc1 Focusing Failed - star is too dim (TCF-S) 04:18:39     Target Completed Target completed (10/25, GCVS ER UMa) 04:18:41   Queue Paused Queue paused for SoftSuspend 04:18:45 Session Suspended Session suspended 04:19:33   Shutter Closed Shutter closed (closing time 49s) 04:29:51     Target Cancelled Target cancelled (11/25, GCVS AM CVn) due to other condition 04:38:12     Target Cancelled Target cancelled (12/25, GCVS GK Per) due to cloud 04:46:51     Target Cancelled Target cancelled (13/25, GCVS SY Cnc) due to cloud 04:57:24     Target Cancelled Target cancelled (14/25, GCVS RZ LMi) due to cloud 05:07:42     Target Cancelled Target cancelled (15/25, GCVS DY Per) due to cloud 05:15:48     Target Cancelled Target cancelled (16/25, GCVS R CrB) due to cloud 05:26:13     Target Cancelled Target cancelled (17/25, GCVS U Her) due to cloud 05:36:24     Target Cancelled Target cancelled (18/25, GCVS AM Her) due to cloud 05:46:45     Target Cancelled Target cancelled (19/25, 38P/Stephan-Oterma) due to cloud 05:59:17     Target Cancelled Target cancelled (20/25, GCVS CN Leo) due to cloud 06:10:51     Target Cancelled Target cancelled (21/25, K2-18) due to cloud 06:20:57     Target Cancelled Target cancelled (22/25, 38P/Stephan-Oterma) due to cloud 06:33:46     Target Cancelled Target cancelled (23/25, GCVS S Cyg) due to cloud 06:43:32     Target Cancelled Target cancelled (24/25, GCVS SS Her) due to cloud 07:11:39     Target Cancelled Target cancelled (25/25, 46P/Wirtanen) due to cloud 07:11:44   Queue Completed Job Queue completed 07:11:49 Session Closing Session closing 07:11:54   Shutter Closed Shutter already closed (closed at 04:19, closing time 49s) 07:12:45   Dome Parked Dome parked (parking time 51s) 07:12:57   Telescope Parked Telescope parked (parking time 11s) 07:13:42 Session Housekeeping Housekeeping Started (Cleanup FITS, Create Fits Summary, Transfer Files) 07:13:55 Session Finished Session Finished

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Operational Issues (2019-12-16, S729)

• Critical Issues (0)
• Major Issues (1)
• Minor Issues (2)
• Continuous Improvement (0)

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Critical Issues

• None

Major Issues

• AstroMain program crashed at 02:20 due to an unhandled NullReference exception.  Error seems to have occurred in ReportTime routine and  related to an issue with TheSky6 Utils class not being setup, and possibly to the use of Utils class in DomeChart's  DrawChartBase routine. Statement has now been placed with a 'Try, Except, End Try' block
  Fixed 2019-12-18 (AstroMain 3.18.7)

Minor Issues

• Stars observed to be drifting eastwards compared to motion of the telescope. This is noticed on PHD2 History Graph when used Imaging Assistent to follow a star with guiding disabled.  This produced unnecessary extra guiding and makes it difficult to use PHD2 to examine the residual periodic error from the mount the Imaging.  Tracking Rate examined in the Scope AutoStar II Handbox and found to be set a custom rate of -27  x 0.01ths.   This is solar tracking rate and the LX200's tracking raye was presumably set to this value for the Mercury Transit (attempt) and not reset again afterwards.  Issue fixed by re-setting LX200 Tracking Rate to Sidereal.
  Fixed 2019-12-17 (Observatory)
   
• When connecting to Telescope using the 'Connect Scope' button, an 'Object variable or With block variable not set' message' is sometimes reported in response to 'Establishing link.  The Scope connects OK in TheSky and operations appear to be unaffected but several rows of information are skipped over when the exception occurs.  Error is probably associated with the statement 'LST = Utils.ComputeLocalSiderealTime' based on problems seen with Utils.method calls in DomeCharts.DrawChartBase.   Statement has been placed within a  'Try, Except, End Try' block to localise the problem
  Fixed 2019-12-20 (AstroMain 3.18.7)

Continuous Improvement

• None

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Guiding Calibration (update to 0.90 guiding rate)

Following installation of 2" Field Flattener on the 80mm APO secondary scope (see  2" Field Flattener (TSFLAT2), 2019-12-11) the ZWO 178MC camera using for guiding was orientated into an approximately north up position (camera angle 359.5 deg),  the guide speed on the LX200 mount was increased to 90 (0.90x sidereal) and a fresh guiding calibration made.

Note: PHD2 automatically gets the Dec Guide speed  from the Mount using ASCOM. 
(it is always seems to be  0.01x higher than the value shown on the AutoStar II handbox.  So +90 guiding rate in AutoStar II becomes  0.91x in PHD2)

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Tracking Rate (reset to sidereal rate)

It had been noticed in the last few sessions that stars in PHD2 appeared to be drifting eastwards when guiding output was disabled (as occurs when Guiding Assistent is being used). The Dec line would rapidly exceed the +/- 16 arc sec maximum graph range in PHD2 and it was impossible to examine the residual periodic error using PHD2.  With a possible adjustment in the Scope's Tracking Rate in mind it was found that the existing tracking as displayed on the  LX200's AutoStar II Handbox was lying at a custom rate of -27  x  .01% sidereal .   This is the solar tracking rate and it seems that the LX200's tracking rate was set to this value for the Mercury Transit (attempt) and not reset again afterwards. 

Issue was fixed by re-setting LX200 Tracking Rate to Sidereal. An 8 minute run was then made using PHD2's Guiding Assistent looking at a star at the South Sky Point (Az 180, Dec 0). The run shows a slight westward drift of the star (-1.20 arc sec/min), but the Mount's residual Periodic Error (12.9 arc sec peak to peak) was at least now visible.  The declination drift was small (0.15 arc sec/min) showing the mount has a very good  polar alignment in azimuth.

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Declination Backlash (anti-backlash re-tried)

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

These were all done using Guide Speed x0.90 (ie. a guide speed of ~13.5 arc sec/sec) and a Anti-Dec Backlash Setting in the mount of 150%

 

The following screen shots show Backlash Charts after scope rebalancing and inclusion of anti-backlash setting of 150 in scope

South Sky Point (due South, Dec 0°, Alt 32°)
New Backlash Chart  (includes Anti- Dec Backlash Setting in Scope of 150)		Earlier Backlash Chart (2019-12-10)
New Backlash Chart (repeat) (after resetting RA Tracking Rate back to Sidereal)
Mid Sky  (due South/Dec 30°, Alt 62° )
New Backlash Chart  (includes Anti- Dec Backlash Setting in Scope of 150)		Earlier Backlash Chart (2019-12-10)
Near Zenith Sky  (due South/Dec 50°, Alt 82° )
New Backlash Chart  (includes Anti- Dec Backlash Setting in Scope of 150)		Earlier Backlash Chart (2019-12-10)

Average residual dec backlash  was 825 ms (11.0 arc sec).   Range 423-1062 (5.3 - 14.1 arc sec)

• Forward Plan
  
  - Review Guiding Charts associated with various targets to ensure they don't show any significant Dec oscillation or retrograde motion.
     >> To be examined
  

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