David's Astronomy Pages
Notes - Session 945 Attempt (2021-12-27)

 
Bullet Session Aims & Highlights
 - Observing Result
 - Night Summary Plot
 - Session Event Log
 
Bullet Operational Issues
  - Critical Issues (0),  Major Issues (0),  Minor Issues (3),  Small Defects (2),  Continuous Improvement (1)
 
Bullet No Images from 2021-12-24 >>         [ Local Files >> ]
2021-12-28
Bullet Guiding Review - Lock Position Adjustments & Lost Star Events

Session Aims & Highlights (2021-12-27)

Main aims

  1. Guiding Manager. Test out new method for limiting impact of Dec Backlash
  2. AstroMain. Test out new 3.48.10 version with a fix for Cloud Measurements for current scope position and next 3 targets (TP2 Record)
  3. Targets.  Acquire images of any targets if conditions allow.

Equipment & Software

Highlights

Notes:

  Summary Plots & Logs

Observing Result
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Dome & Scope Slewing Performance
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Slew/Centering Performance
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Guiding Performance
Reasons for poor Dec guiding :
Black Point (1) - Cloud   -
Red points (3)   -

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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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Session Event Log
Time     Event Detail
16:55:50 Session Monitoring AutoStart monitoring for Live Session opportunity between 16:55 & 06:27
16:55:51   AutoStart Delayed Session delayed due to too few stars
17:02:32 Session AutoStarting Session autostarting (17:02)
17:03:00 Session Created Live Session Created (2021-12-27 S00945, ImageSaveNum: 945001)
17:03:02   Scope Switched On Telescope Power has been switched on via UPB Powerbox.
17:04:44   Services Started Observatory Services started
17:04:50 Observatory (Auto) Observatory placed in Fully-Automated Mode
17:04:52 Session Pending Session pending (2021-12-27)
17:04:54 Session Initiating Session initiating (2021-12-27)
17:04:56   Plan Requested Observing Plan requested from AstroPlan (1.29.2)
17:05:30   Plan Loaded Observing Plan loaded to queue (, Plan ID: 698)
17:05:52   Camera1 Connected SBIG Camera Connected (set point -20°C)
17:05:59   Telescope Connected Telescope Connected (TheSky6)
17:06:23 Session Equilibration Session ready for dome & camera equilibration
17:07:08   Dome Opened Dome opened (opening time 45s)
17:07:58 Session Running Session running
17:08:00   Queue Started Observing Queue started (44 targets selected)
17:08:03     Target Started (NrZen) Target started (Focus Field 23, HIP 113729)
17:09:51       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
17:12:48       Focusing Completed Foc1 AutoFocus Completed (Profile No 1, wide)
17:15:11       Focusing Completed Foc1 AutoFocus Completed (Profile No 1)
17:15:13       Focusing Started-Foc2 Foc2 Focusing Started (Secondary Scope, using ShCap)
17:17:22       Focusing Completed Foc2 AutoFocus Completed (Profile No 2, wide)
17:19:08       Focusing Completed Foc2 AutoFocus Completed (Profile No 2)
17:19:25     Target Completed Target completed (Focus Field 23, HIP 113729)
17:20:00     Target Started (1/44) Target started (1/44, C/2017 K2 (PANSTARRS))
17:23:47       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
17:26:03       Focusing Completed Foc1 AutoFocus Completed (Profile No 3)
17:33:51   SoftSuspend Called Soft Suspend is called due to Deteriorating Conditions (too few stars)
17:35:01 Critical Cloud Alert Critical Cloud Alert (Obs.Manager will close the Dome)
17:35:03   HardSuspend Called Hard Suspend is called due to Critical Conditions (cloud)
17:35:06     Target Aborted (1/44) Target aborted (1/44, C/2017 K2 (PANSTARRS)) due to cloud
17:35:08   Queue Paused Queue paused for Session Suspension
17:35:10 Session Suspended Session suspended
17:35:56   Dome Closed Dome closed (closing time 50s)
17:49:08     Target Cancelled Target cancelled (2/44, GCVS SS Cyg) due to cloud
17:58:41     Target Cancelled Target cancelled (3/44, GCVS BL Lac) due to cloud
18:13:11     Target Cancelled Target cancelled (4/44, 19P/Borrelly) due to cloud
18:32:48     Target Cancelled Target cancelled (5/44, UGC 1971 w/SN2021afkk) due to cloud
18:43:58     Target Cancelled Target cancelled (6/44, GCVS HH And) due to cloud
19:02:55     Target Cancelled Target cancelled (7/44, AT2021hfr) due to cloud
19:25:17     Target Cancelled Target cancelled (8/44, NGC 1587) due to cloud
19:38:49     Target Cancelled Target cancelled (9/44, GSC 1224:29) due to cloud
20:16:25     Target Cancelled Target cancelled (10/44, PGC 3792) due to cloud
20:34:51     Target Cancelled Target cancelled (11/44, 132P/Helin-Roman-Alu) due to cloud
20:48:05     Target Cancelled Target cancelled (12/44, Nova Cas 2021) due to cloud
21:07:27     Target Cancelled Target cancelled (13/44, LEDA 2204848 w/SN2021umh) due to cloud
21:29:49     Target Cancelled Target cancelled (14/44, UGC 2528 w/SN2020adnx) due to cloud
21:46:11     Target Cancelled Target cancelled (15/44, Nova Per 2020) due to cloud
22:06:34     Target Cancelled Target cancelled (16/44, NGC 1400 w/AT2021hcz) due to cloud
22:19:11     Target Cancelled Target cancelled (17/44, GCVS DY Per) due to cloud
22:30:33     Target Cancelled Target cancelled (18/44, AT2021aeoz (CV)) due to cloud
22:50:25     Target Cancelled Target cancelled (19/44, AT2021xrf) due to cloud
23:12:17     Target Cancelled Target cancelled (20/44, NGC 1569 w/AT2021aczn) due to cloud
23:34:09     Target Cancelled Target cancelled (21/44, NGC 7446 w/SN2021agdd) due to cloud
23:50:39     Target Cancelled Target cancelled (22/44, C/2019 L3 (ATLAS)) due to cloud
00:10:16     Target Cancelled Target cancelled (23/44, UGC 3855 w/SN2021agco) due to cloud
00:24:08     Target Cancelled Target cancelled (24/44, AT2021agdv (CV)) due to cloud
00:44:34     Target Cancelled Target cancelled (25/44, Scholz's Star) due to cloud
00:57:23 Session Resuming Session resuming
00:58:08   Dome Opened Dome opened (opening time 45s)
00:58:11 Session Running Session running
00:58:13   Queue Resumed Observing Queue resumed
00:58:15     Target Started (26/44) Target started (26/44, NGC 2716)
01:12:27     Target Completed Target partially completed (26/44, NGC 2716)
01:12:32     Target Started (27/44) Target started (27/44, 67P/Churyumov-Gerasimenko)
01:17:53       Focusing Started-Foc1 Foc1 Focusing Started (TCF-S)
01:20:05   SoftSuspend Called Soft Suspend is called due to Deteriorating Conditions (too few stars)
01:20:32       Focusing Completed Foc1 AutoFocus Completed (Profile No 4)
01:22:36 Critical Cloud Alert Critical Cloud Alert (Obs.Manager will close the Dome)
01:22:38   HardSuspend Called Hard Suspend is called due to Critical Conditions (cloud)
01:22:40     Target Aborted (27/44) Target aborted (27/44, 67P/Churyumov-Gerasimenko) due to cloud
01:22:42   Queue Paused Queue paused for Session Suspension
01:22:44 Session Suspended Session suspended
01:23:31   Dome Closed Dome closed (closing time 50s)
01:27:08     Target Cancelled Target cancelled (27/44, 67P/Churyumov-Gerasimenko) due to cloud
01:47:15     Target Cancelled Target cancelled (28/44, AT2021rl) due to cloud
02:09:08     Target Cancelled Target cancelled (29/44, NGC 2761 w/AT2021aggu) due to cloud
02:21:01     Target Cancelled Target cancelled (30/44, GCVS SY Cnc) due to cloud
02:41:08     Target Cancelled Target cancelled (31/44, UGC 4550) due to cloud
03:03:00     Target Cancelled Target cancelled (32/44, UGC 4671 w/SN2021afsj) due to cloud
03:25:26     Target Cancelled Target cancelled (33/44, UGC 4719) due to cloud
03:46:48     Target Cancelled Target cancelled (34/44, NGC 3254) due to cloud
04:08:40     Target Cancelled Target cancelled (35/44, NGC 2955 w/AT2021jtt) due to cloud
04:30:32     Target Cancelled Target cancelled (36/44, NGC 3310 w/SN2021gmj) due to cloud
04:42:20     Target Cancelled Target cancelled (37/44, GCVS AM CVn) due to cloud
05:01:57     Target Cancelled Target cancelled (38/44, NGC 3836 w/SN2021aefs) due to cloud
05:23:49     Target Cancelled Target cancelled (39/44, NGC 4896 w/SN2021wad) due to cloud
05:45:41     Target Cancelled Target cancelled (40/44, UGC 8975 w/AT2021adpe) due to cloud
06:07:33     Target Cancelled Target cancelled (41/44, NGC 3389 w/AT2021hkw) due to cloud
06:29:25     Target Cancelled Target cancelled (42/44, UGC 8426 w/AT2021knq) due to cloud
06:51:47     Target Cancelled Target cancelled (43/44, Hickson 81) due to cloud
07:13:23     Target Cancelled Target cancelled (44/44, GCVS SS Her) due to other condition
07:13:28   Queue Completed Job Queue completed
07:13:33 Session Closing Session closing
07:13:38   Dome Closed Dome already closed (closed at 01:23, closing time 50s)
07:14:18   Dome Parked Dome parked (parking time 32s), Az: 90.0 deg
07:15:51   Telescope Parked Telescope parked (parking time 87s)
07:16:11   Telescope State Scope parked Turn scope off. (Handbox)
07:16:47   Telescope Switched Off Telescope Power has been switched off via UPB Switch.
07:17:40   Services Stopped Night Services stopped
07:17:42 Session Housekeeping Housekeeping Started (Cleanup FITS, Create Fits Summary, Transfer Files)
07:17:43 Session Finished Session Finished
 
Session Alerts
Time     Alert Detail
00:00:01 Dome Alert DomeRecords have stopped updating
00:00:21 Dome Alert DomeRecords have resumed updating

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Operational Issues (2021-12-27, S945A)

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2021-12-28


Guiding Review - Lock Position Adjustments & Lost Star Events

Lock Position Adjustments
Lock Position adjustments are being tried during guide settling in order to overcome issues with Dec backlash & backlash overcompensation.  In situation where guide star starts out on the wrong side of zero line for planned uni-directional guiding or where first guide pulse pushes the guide star onto the wrong side of the zero line, a simple adjustment of lock position can be used to quickly bring the guide star 'back' to the zero line without any of the side effects of swamping the Dec Guide Mode only to swap it back later on, with the extra uncertainty that brings to Dec position.

During S944 session the lock position adjustments were initially being made in the wrong direction leading to Dec Guiding RunAway. After fixing that issue it was found that  3 or 4 times the required number of adjustments were being made, leading to overadjustment.    This was fixed in the Astrom 3.48.10 version.

During te S945A sessionn attempt it was found that extra adjustments were being made before the impact of the initial adjustment had fed through and impacted the new guide error values.  This caused the star position to be over adjusted by factor of 2 or 3. A new lock position adjustment should either wait a minimum time (eg. 5s) or wait for associate star lock change event to be received.  Relying on reading lock position isn't sufficient.

In the following chart Dec position jumps from +4.0 to -8.0 as a consequence of the accumulation of 3 lock shift adjustments (indicated by short purple line markers at around 17:23:25)

Image

Looking at AstroMain's log file (see extract below) it seems that although New Lock Positions are reported at 23:26.67,  23:27.54,  23:28.51, the G.dy values of 3.97" and 4.47" at 23:26.79 and 23:27.66 are clearly associated with error calculations that don't use the new lock positions.   PHD2 events recording 'LockPositionSet' aren't  apparently received until 23:28.51 to 23:28.75.  Three adjustments (3.63, 3.85, 4.34 = 11.8 px total) explains why the Dec Error jumped from +4 to -8.

17:23:25.78 | Starting Guide Monitor (17:23:25)
17:23:25.92 | Y Adjustment Required: PrincipalDecMode=North, G.dy=3.75", yAdj=3.63 px
17:23:26.24 | Calling GuidingChart.DrawFocusChange, MoveSteps = 514
17:23:26.67 | New Lock Position x: 2,168.22, y: 535.40, y_adj: 3.63

17:23:26.79 | Y Adjustment Required: PrincipalDecMode=North, G.dy=3.97", yAdj=3.85 px
17:23:27.54 | New Lock Position x: 2,168.22, y: 539.25, y_adj: 3.85

17:23:27.66 | Y Adjustment Required: PrincipalDecMode=North, G.dy=4.47", yAdj=4.34 px
17:23:28.51 | New Lock Position x: 2,168.22, y: 543.59, y_adj: 4.34

17:23:28.51 | PHD2 event during guiding :LockPositionSet
17:23:28.63 | PHD2 event during guiding :LockPositionSet
17:23:28.75 | PHD2 event during guiding :LockPositionSet

Examining the log of PHD2 client-server communications (see extract below) shows that the set  lock position at 23:26.24 was associated with GuideStep event at 23:19.24 (7 seconds earlier),   with set lock position at 23.27.10 being associated with GuideStep event at 23:21.93 (5 seconds earlier),  with set lock position at 23:28.10 being associated with GuideStep event at 23:26.08 some (2 seconds earlier).     

17:23:18.89 | Event << {"Event":"SettleDone","Error":"timed-out waiting for guider to settle",
17:23:19.24 | Event << {"Event":"GuideStep","dy":3.632,
17:23:21.93 | Event << {"Event":"GuideStep","dy":3.849,
17:23:25.08 | Event << {"Event":"GuideStep","dy":4.335,

17:23:25.92 | 92 REQUEST >> {"method": "get_lock_position", "id": 92}
17:23:25.94 | 92 Response << {"jsonrpc":"2.0","result":[2168.22,531.77],"id":92}

17:23:26.24 | 93 REQUEST >> {"method": "set_lock_position", "params": [2168.22, 535.402], "id": 93}
17:23:26.25 | Event << {"Event":"LockPositionSet", Y":535.402}
17:23:26.56 |
17:23:27.10 | 96 REQUEST >> {"method": "set_lock_position", "params": [2168.22, 539.249], "id": 96}
17:23:27.12 | Event << {"Event":"LockPositionSet", "Y":539.249}
17:23:27.42 |
17:23:28.10 | 99 REQUEST >> {"method": "set_lock_position", "params": [2168.22, 543.585], "id": 99}
17:23:28.12 | Event << {"Event":"LockPositionSet", "Y":543.585}
17:23:28.40 |
17:23:32.02 | Event << {"Event":"GuideStep", "dy":-7.722,
17:23:36.45 | Event << {"Event":"GuideStep", "dy":-7.482,
17:23:40.31 | Event << {"Event":"GuideStep", "dy":-4.446,
17:23:43.96 | Event << {"Event":"GuideStep", "dy":-2.476,
17:23:47.49 | Event << {"Event":"GuideStep", "dy":-0.691,
17:23:50.47 | Event << {"Event":"GuideStep", "dy":-0.235,
17:23:53.58 | Event << {"Event":"GuideStep", "dy":0.491,

There is a 7 second gap in GuideStep events between 23:25.08 and 23:32.02.  It is unclear if this represents a) a real physical delay between PHD2 guide step images, b) an impact/delay to PHD2 due to increased in communications/processing between server and client associated with Get /Set Lock Position requests, or c) loss of guide step event in AstroMain.

Between the two guidestep events (where dy jumps from +4.33 to -7.72) there are 3 set lock position requests that collectively move Lock Position's Y value from 531.77 to 543.58. 

Lost Star Event
Guide Run 2 suffered from a couple of large RA excursions (a 7" excursion during setting and a 5" excursion during 1st frame).  The excursions appear to have begun with lost star events. Since the SNR is fairly reasonable and doesn't change it seems unlikely that cloud caused the star to be lost. Similarly the absence of any deviation in Dec position makes it unlikely that cable hang-up was responsible.   It is hypothesised that a very fast acting error in Ra drive smeared the light from the guide star which was seen by PHD2 as a lost star.

Current algorithum deliberately suspends guide output for 20s following 'StarLost' event. This is done because guiding when there is passing cloud has been found to worse than no guiding at all.  However in this case guiding would have been clearly have been very helpful to limiting and/or correcting the RA excursion.   As a first step the suspension of guide output will not be applied when guide star SNR is > 40 or the number of continuous lost star events is < 4.

Image

 

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