David's Astronomy - Notes 2021-08-31 (S0910)

Issue: Scope appearing to fail to slew to the first 2 targets / targets aborted without imaging.

Description
First two targets, Target 1/20 (UGC 10607) & Target 2/20 (NGC 6500), both failed with the message 'Scope isn't pointing to the target (Ang Sep. = xx arc degs)' and the targets were aborted by the job executor without any imaging. User intervention was made to cancel the run and restart the observatory software.

Analysis
Post-session link of Focus Locate Frame (Focus Field 20) taken at 22:39 was good and confirmed that the scope had slewed ok and was sitting at the expected Near Zenith location. (Scope was possibily already on location already following earlier slew to 'Focus Field 20' at 22:30.

Scope then made a programmed to slew to Target 1/20 (UGC 10607 at RA: 16 55 09.389, Dec: +26 39 49.28, Az 252.2°. Alt 42.6°) but the Job Executor reported 'Scope isn't pointing to the target (Ang Sep. = 41.9 arc degs)' and aborted the target. Slew table shows scope reached Az 252.4, Alt 42.2 which is close to the planned target. Review the target position in TheSky6 confirms that original target details (Ra/Dec, Az/Alt). ScopePath confirms that scope reached Ra 16.9156 h, Dec: 26.35°   Post-Slew coordinates were logged as Ra= 16 54 57.000 Dec=+26 21 05.00 (at LT 22:50:04.62). However a fraction of a second later (at 22:50:04.71) the log file reports a post-slew position of RA= 20 01 44.978 Dec= +48 19 28.80, which is identical to the pre-slew position.    This later figure was used by the job executor to conclude that the scope was a long way from the planned target.   ObsCam pictures however clearly show that the the scope slewed to the planned target and didn't remain at the pre-slew position (Focus Field 20).

After aborting the 1st target the scope was commanded to slew to Target 2/20 (NGC 6500 at RA: 17 56 02.513, Dec: +18 21 14.07, Az 232.1° Alt 41.9° ). Pre-slew position was logged at 22:56:56 as being Ra= 16 54 57.000 Dec=+26 21 00.00 (incidentally this is consistent with the UGC 10607 location)   Logged Scope Path and ObsCam shows the scope making the planned slew to NGC 6500. At 22:57:22 the post-slew position was logged Ra= 17 56 12.000 Dec=+18 04 48.00, but at 22:57:23 pre-slew and post-slew positions were both logged as being at RA= 20 01 44.978 Dec= +48 19 28.80. Again it was these later figures that were used by the job executor to conclude that scope was a long way from the planned target.

The problems delayed the effective start of the session by around one hour. Problem was fixed in-session by aborting the session, parking scope, restarting all observatory software and then restarting session. This seems to resolve the issue. Logs to be reviewed post-session to try to understand what might have caused the issue and determine whether any further actions are required.

Obs.Manager froze at 22:23:39 following Dome Error 'Killing existing OpenDomeTask as it appears to have stalled (97s)'. Obs.Manager resumed between 22:27:14 to 22:27:19. after Dome Error : Exception in CloseShutterTask, the remote procedure call failed , HRESULT.. in CloseShutter(ByThread). At 22:28:39 killing existing OpenDomeTask as it appears stalled (412s). Variety of other exceptions up to 22:28    Restarted Session at 23:06,

Reviewing code shows the 'offending' post-slew coordinates come following a call to TheSky6.Telescope.GetRaDec()
(dRaPostSlew = Telescope.dRA , dDecPostSlew = Telescope.dDec),   and are compared against 'questionable' pre-slew coordinates that came following an earlier call to
TheSky6.Telescope.GetRaDec() (dRaPreSlew = Telescope.dRA, dDecPreSlew = Telescope.dDec).   The proceeding 'good' post-slew coordinates come from a calls to objScope.RightAscension & objScope.Declination.   It was seem that the TheSky6.Telescope had somehow become detached from the live telescope driver and didn't provide live Ra/Dec values but was providing older frozen values.

Data reported during connection to the TheSky6.Telescope at 22:21 indicated a clear discrepency between telescope coordinates reported by TheSky6 and those reported by ASCOM direct. It is possible that this was due to the TheSky6 not using computer time and that this setting was then manually switched in response to seeing the discrepency. This can not howevre be confirmed either way. Afthough Telescpe.GetRaDec() appeared to not be giving fresh coordinates, calls to TheSky6.Telescope.Asynchronous = 1
and to TheSky6.Telescope.SlewToRaDec clearly worked ok.     Clearly that was a glitch of some kind, but was this something in TheSky6 upon a problem with two copies of the TheSky6 running, one with TheSky6 UI and a second background one that hadn't closed from the proceeding session.

Foward Actions
- Could add code to demonstrate that there is a discrepency between ASCOM and TheSky positions and raise an alert ?
- Could add code to detect if there are two copies of TheSky that appear be running at the same time ?


	Session Aims & Highlights
	- Observing Result - Night Summary Plot - Session Event Log

	Operational Issues
	- Critical Issues (0), Major Issues (2), Minor Issues (13), Small Defects (0), Continuous Improvement (20)

	Images from 2021-08-31 >> [ Local Files >> ]

	Investigation - Targets failed with message 'scope isn't pointing to the target' even though they were

This Web Page:	Notes - Session 910 (2021-08-31)
Last Updated :	2024-09-30
Site Owner :	David Richards
Home Page :	David's Astronomy Web Site

David's Astronomy Pages
Notes - Session 910 (2021-08-31)

Session Aims & Highlights (2021-08-31)

Operational Issues (2021-08-31, S910)

Investigation - Targets failed with message 'scope isn't pointing to the target' even though they were

David's Astronomy Pages Notes - Session 910 (2021-08-31)

Session Aims & Highlights (2021-08-31)

Operational Issues (2021-08-31, S910)

Investigation - Targets failed with message 'scope isn't pointing to the target' even though they were

David's Astronomy Pages
Notes - Session 910 (2021-08-31)