David's Astronomy Pages Notes - Session 735 (2020-01-02)

Notes (S734)

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Notes (S736)

	Session Aims & Highlights
	- Observing Result  - Night Summary Plot  - Session Event Log
	Operational Issues
	- Critical Issues (0),  Major Issues (0),  Minor Issues (3),  Continuous Improvement (3)
	Guiding Performance
	Investigation:  Failed Focus Profile
	Images from 2020-01-02  >>

Session Aims & Highlights (2020-01-02)

Main aims

1. Targets: Acquire images of a selection of targets including deep sky objects, variable stars, nearby stars and comets.
2. Guiding:  Continue checking guiding performance after recent changes

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 3.18.11 ,  Astroguard 1.2.9,   AstroPlan 1.13.7,  AstroShCap 1.2.10, AstroVOE 1.3.4, UPB 1.4.17  (AstroWeather 1.8.2, AstroAllSky 3.5.1)

Highlights

• Targets. x targets successfully acquired.

Lowlights

•   Guiding Performance.   Several targets suffered from poor guiding in Declination. due to variable backlash experienced at different points in the sky.

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  In the event skies

Session Event Log

Time     Event Detail 01:22:41 Session Created Live Session Created (2020-01-02 S00735, ImageSaveNum: 735001) 01:23:19   Scope Switched On Telescope Power has been switched on via UPB Powerbox. 01:25:02   Services Started Observatory Services started 01:25:28   Camera1 Connected SBIG Camera Connected (set point -20°C) 01:25:43 Observatory (Auto) Observatory placed in Fully-Automated Mode 01:25:47 Session Pending Session pending (2020-01-02) 01:25:49 Session Initiating Session initiating (2020-01-02) 01:25:51   Plan Requested Observing Plan requested from AstroPlan (1.13.7) 01:26:22   Plan Loaded Observing Plan loaded to queue (2020-01-02 V1 BEST PLAN, Plan ID: 441) 01:26:27   Camera1 Connected SBIG Camera Connected (set point -20°C) 01:26:35   Telescope Connected Telescope Connected (TheSky6) 01:26:48 Session Equilibration Session ready for dome & camera equilibration 01:27:34   Shutter Opened Shutter opened (opening time 46s) 01:27:37   Equilibration Started Dome Equilibration started 01:29:34   Equilibration Skipped Dome Equilibration skipped by user 01:29:36 Session Running Session running 01:29:38   Queue Started Observing Queue started (20 targets selected) 01:30:51       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S) 01:33:20       Focusing Failed Foc1 Focusing Failed - failed QC check (Range) 01:33:22       Focusing Started Foc2 Focusing Started (Secondary Scope, using ShCap) 01:34:39       Focusing Failed Foc2 Focusing Failed - star lost 01:34:41     Target Started (1/20) Target started (1/20, GCVS FU Ori) 01:39:41     Target Completed Target completed (1/20, GCVS FU Ori) 01:39:43     Target Started (2/20) Target started (2/20, GCVS RR Tau) 01:41:43       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S) 01:43:30       Focusing Completed Foc1 AutoFocus Completed (Profile No 3) 01:50:07     Target Completed Target completed (2/20, GCVS RR Tau) 01:50:09     Target Started (3/20) Target started (3/20, GCVS CN Ori) 01:52:33       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S) 01:54:33       Focusing Failed Foc1 Focusing Failed - failed QC check (Quadratic) 01:55:01   SoftSuspend Called Soft Suspend is called due to Deteriorating Conditions (too few stars) 01:58:01     Target Completed Target completed (3/20, GCVS CN Ori) 01:58:03   Queue Paused Queue paused for SoftSuspend 01:58:05 Session Suspended Session suspended 01:58:51   Shutter Closed Shutter closed (closing time 49s) 02:00:47 Session Resuming Session resuming 02:01:32   Shutter Opened Shutter opened (opening time 45s) 02:01:34 Session Running Session running 02:01:36   Queue Resumed Observing Queue resumed 02:01:38     Target Started (4/20) Target started (4/20, Scholz's Star) 02:06:27   SoftSuspend Called Soft Suspend is called due to Deteriorating Conditions (too few stars) 02:07:07 Critical Cloud Alert Critical Cloud Alert (Obs.Manager will close the Shutter) 02:07:09   HardSuspend Called Hard Suspend is called due to Critical Conditions (cloud) 02:07:11     Target Aborted (4/20) Target aborted (4/20, Scholz's Star) due to cloud 02:07:13   Queue Paused Queue paused for SoftSuspend 02:07:15 Session Suspended Session suspended 02:07:17   Queue Paused Queue pausing for HardSuspend 02:08:02   Shutter Closed Shutter closed (closing time 49s) 02:14:08     Target Cancelled Target cancelled (4/20, Scholz's Star) due to cloud 02:24:34 Session Resuming Session resuming 02:24:44     Target Cancelled Target cancelled (5/20, LAMOST-HVS1) due to other condition 02:25:19   Shutter Opened Shutter opened (opening time 45s) 02:25:22 Session Running Session running 02:25:24   Queue Resumed Observing Queue resumed 02:25:26     Target Started (6/20) Target started (6/20, GCVS CM Tau) 02:27:32       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S) 02:29:32       Focusing Failed Foc1 Focusing Failed - failed QC check (Quadratic) 02:43:46     Target Completed Target completed (6/20, GCVS CM Tau) 02:44:34     Target Started (7/20) Target started (7/20, GCVS U Gem) 02:47:15       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S) 02:49:56       Focusing Completed Foc1 AutoFocus Completed (Profile No 6) 02:53:17   SoftSuspend Called Soft Suspend is called due to Deteriorating Conditions (too few stars) 02:53:22     Target Completed Target completed (7/20, GCVS U Gem) 02:53:25   Queue Paused Queue paused for SoftSuspend 02:53:27 Session Suspended Session suspended 02:54:16   Shutter Closed Shutter closed (closing time 49s) 03:03:19     Target Cancelled Target cancelled (8/20, GCVS DX Cnc) due to other condition 03:08:43 Session Resuming Session resuming 03:09:28   Shutter Opened Shutter opened (opening time 46s) 03:09:31 Session Running Session running 03:09:33   Queue Resumed Observing Queue resumed 03:09:35     Target Started (9/20) Target started (9/20, GCVS RZ LMi) 03:17:56     Target Completed Target completed (9/20, GCVS RZ LMi) 03:17:58     Target Started (10/20) Target started (10/20, GCVS CN Leo) 03:21:51       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S) 03:24:00       Focusing Completed Foc1 AutoFocus Completed (Profile No 7) 03:31:21     Target Completed Target completed (10/20, GCVS CN Leo) 03:31:23     Target Started (11/20) Target started (11/20, Rose 9) 03:34:45       Focusing Failed Foc1 Focusing Failed - star is too dim (TCF-S) 03:51:07     Target Completed Target completed (11/20, Rose 9) 03:51:09     Target Started (12/20) Target started (12/20, IC 3322) 03:52:46       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S) 03:54:57       Focusing Failed Foc1 Focusing Failed - failed QC check (Quadratic) 04:11:19     Target Completed Target completed (12/20, IC 3322) 04:11:21     Target Started (13/20) Target started (13/20, IC 3474) 04:12:51       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S) 04:14:57       Focusing Completed Foc1 AutoFocus Completed (Profile No 9) 04:26:35   SoftSuspend Called Soft Suspend is called due to Deteriorating Conditions (too few stars) 04:31:21     Target Completed Target completed (13/20, IC 3474) 04:31:23   Queue Paused Queue paused for SoftSuspend 04:31:27 Session Suspended Session suspended 04:32:15   Shutter Closed Shutter closed (closing time 49s) 04:51:37     Target Cancelled Target cancelled (14/20, NGC 4666) due to cloud 05:13:39     Target Cancelled Target cancelled (15/20, NGC 5058) due to cloud 05:35:31     Target Cancelled Target cancelled (16/20, NGC 5600) due to cloud 05:57:23     Target Cancelled Target cancelled (17/20, Hickson 72) due to cloud 06:19:15     Target Cancelled Target cancelled (18/20, SHK 19) due to cloud 06:41:07     Target Cancelled Target cancelled (19/20, Rose 32) due to wind 07:16:01     Target Cancelled Target cancelled (20/20, NGC 5468) due to wind 07:16:06   Queue Completed Job Queue completed 07:16:11 Session Closing Session closing 07:16:15   Shutter Closed Shutter already closed (closed at 04:32, closing time 49s) 07:16:51   Dome Parked Dome parked (parking time 35s) 07:17:02   Telescope Parked Telescope parked (parking time 11s) 07:17:50 Session Housekeeping Housekeeping Started (Cleanup FITS, Create Fits Summary, Transfer Files) 07:17:59 Session Finished Session Finished

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Operational Issues (2020-01-02, S735)

• Critical Issues (0)
• Major Issues (0)
• Minor Issues (3)
• Continuous Improvement (3)

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Critical Issues

• None

Major Issues

• None

Minor Issues

• A new feature added in AstroMain 3.18.11 to automatically turn off scope power during observatory shutdown failed with the message 'Telescope power can not be switched off at this time'. This was caused by a clause in Scope.SetPowerOff routine which prevented powering telescope off from the Observatory Computer when state was closing.
   Fixed 2020-01-02 (AstroMain 3.18.12)
   
• Data is not always correct on Autoguiding Charts. This includes parts of the header.  For example in Guide Run 2 the RA Algorithum was reported as null rather than Hysteresis and Dec Algorithm was reported as Hysteresis rather than LowPass2.  It is difficult to replicate this problem on the Development Computer where Simulators are used.It only seems to only occur on Observatory Computer were real hardware / real world processes are in use.  Some changes made to AstroMain 3.18.12 code that may either fix the issue or better highlight the underlying root cause.
  Largely Fixed  2020-01-15 (AstroMain 3.19.5)
   
• Focus Profile 1 failed due to a rogue FWHM values (1.3) on final focus point (14/14) which produced a quadratic curve fit that failed QC.
  Investigation showed that problems was caused by a rogue cosmic ray/alpha particle hit producing an 'apparent star' object with FWHM of 0.8" (See Investigation:  Failed Focus Profile) . Conclusion is not to make any changes to code  at this time but monitor future autofocusing profile to understand if work is warrented.
  Closed for time being.  User Awareness & Monitor Focus Profiles  (AstroMain & Observatory)

Continuous Improvement

• Add button and routine that will Stop Night Services
   Done 2020-01-02 (AstroMain 3.18.12)
   
• Automatically Stop Night Services when Session Finishes
   Done 2020-01-02 (AstroMain 3.18.12)
   
• Add synthetic star images to Guiding Chart to illustrate the expected impact of guide errors on image quality
   Done 2020-01-03 (AstroMain 3.18.12)

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Guiding Performance

Whilst scope reconfiguration and final balancing has still to be completed the effects of the LX200's large Declination Backlash (3-6s) on autoguiding (with or without Anti-Backlash on the Mount and with/without Backlash Compensation in PHD2) lead to overall poor guiding performance.

AstroMain's autoguiding routine has been updated to utilise uni-directional guiding after an initial period of 60-180s without Dec guiding during which the appropriate direction of required guide is determined.

Examples of guiding results from the session are shown below:

Example of Poor Guiding Performance from Session S734

It is concluded that

• Forward Plan
  
  - Consider starting the Dec Drift monitoring during an extended setting period. This would be instead of during the first 180s frame or first few 45s frames.
     To do
  
  - Consider recording the direction in which the scope comes onto the target (ie from north or from south) and use that to help predict the backlash that may need to be taken up before the guiding is able to move the scope
      To do

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Investigation:  Failed Focus Profile

Whilst taking the first autofocus profile of the session it was noticed that the profile failed its QC check and returned the focuser to its original position.
Examining the profile it was clear that the final point (point 14/14) had an anomalously low FWHM value  of 0.8" compared to a FWHM  value of 12.7" at the adjacent focuser position. This completely threw off the quadratic curve fitting that is used to autopick pick the position of best focus.

  Measure Focus Profile (Focuser1)      
| Image                     | Result    | DRO   | FWHM | HFD   | Temp | Max   | Mag    | SN  | Elong |
| Taking 1.5s box (C)  1/14   Ok        |  2341 |  4.6 |  6.00 |  3.7 |  1919 | -10.84 | 126 |  1.06 | 
| Taking 1.5s box (C)  2/14   Ok        |  2221 |  4.0 |  5.85 |  3.8 |  2132 | -11.00 | 137 |  1.05 | 
| Taking 1.5s box (C)  3/14   Ok        |  2101 |  3.0 |  4.94 |  3.8 |  3292 | -11.25 | 158 |  1.06 | 
| Taking 1.5s box (C)  4/14   Ok        |  1981 |  2.7 |  4.48 |  3.8 |  3808 | -11.30 | 163 |  1.03 | 
| Taking 1.5s box (C)  5/14   Ok        |  1861 |  2.6 |  4.33 |  3.8 |  4055 | -11.36 | 168 |  1.02 | 
| Taking 1.5s box (C)  6/14   Ok        |  1741 |  3.2 |  5.09 |  3.8 |  3006 | -11.21 | 156 |  1.10 | 
| Taking 1.5s box (C)  7/14   Ok        |  1701 |  3.1 |  4.79 |  3.7 |  2997 | -11.24 | 158 |  1.03 | 
| Taking 1.5s box (C)  8/14   Ok        |  1661 |  3.5 |  5.09 |  3.8 |  2604 | -11.12 | 148 |  1.01 | 
| Taking 1.5s box (C)  9/14   Ok        |  1621 |  4.0 |  5.85 |  3.8 |  2074 | -10.98 | 136 |  1.04 | 
| Taking 1.5s box (C) 10/14   Ok        |  1501 |  5.3 |  6.31 |  3.9 |  1488 | -10.72 | 117 |  1.11 | 
| Taking 1.5s box (C) 11/14   Ok        |  1381 |  6.5 |  6.91 |  3.9 |  1201 | -10.46 | 100 |  1.12 | 
| Taking 1.5s box (C) 12/14   Ok        |  1261 |  8.3 |  7.98 |  3.9 |   908 | -10.04 |  77 |  1.03 | 
| Taking 1.5s box (C) 13/14   Ok        |  1141 | 10.5 |  8.74 |  3.9 |   846 |  -9.72 |  61 |  1.06 | 
| Taking 1.5s box (C) 14/14   Ok        |  1021 | 12.7 | 10.86 |  3.9 |   717 |  -9.63 |  58 |  1.45 | 
| Taking 1.5s box (C) 14/14*  Ok        |  1021 |  0.8 |  3.42 |  4.0 |  4625 |  -9.79 |  64 |  1.10 | 

  Calc. Quadratic Fit..       Ok        using 14 points
    bf0 :                     Ok        FP (Curve Fit):   2385

    bf1:                      Ok        FP (Mid Point):   1021 (n= 1, nLo= 1, nHi= 0)
    bf2:                      Ok        FP (P50):         1021
    bf3:                      Ok        FP (Peak):        1021
    QC Best Focus...          Fail      Rejecting Curve Fitted Best Focus Position (2385)

  QC Focus Result..           Fail      Failed QC checks

  Restore Focus Position                
  Moving TCF-S Focuser...     Ok        Position: 1681 (Restore)

Investigating the raw focus frame associated with the anomalous point revealed a bright hot spot that had been caused by a cosmic ray or alpha particle hit on the CCD.  The routine for extracting the focuser positions's  FWHM had taken this object (with its max pixel value of 4625 ADU) instead of the out of focus star (with its pixel value of  600-700 ADU)

Explaining the .SRC file shows how the hot spot a aperature magnitude (-9.788) which is fractionally brighter that that of the star (-9.206)

Discussion
Problem was clearly related to a cosmic ray or alpha particle hit on the CCD which is relatively rare event for a brief (1.5s) focus exposure. This is the first time that such a event has knowingly caused a focus profile to fail.  

Potential fixes that might have caught and rejected the anomalous point on this occasion might have side effects that could either cause valid sharp stars to be rejected or still allow anomalies through.

- A threshold of say 1.5" FWHM would have allowed the 0.8" anomaly to be rejected whilst retaining star values with a peak FWHM of 2.6"
 (however an anomaly of 1.6" would still have been allowed through and invalidated the profile.

- Rejecting the anomaly based on SExtractor star_class could reject sharp stars.

- Rejecting the anomaly based on a significant difference from adjacent point would be difficult to program and could overlook large differences sometimes occuring due to seeing / sky quality anomalies.

- Reducing the focus box reduces the probability of an anomalous hot spot occuring with the same frame,  but making the process more prone to failure during to star drifting / jumping out of the field

Conclusions
Proposal is to not make any modifications for the time being, but monitor the results of autofocusing to understand if this is a significant enough issue to warrent work.

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