Platesolve off by 13.6 degrees even when target in frame

[jabbourk]

I upgraded my computer and re-installed the same drivers and the latest SharpCap. For every plate solve, whether using SharpCap plate solve or cygwin, plate solve reported an error of 13.6 (+/- 0.4) degrees even when the target was in the middle of the field of view. If I agreed to sync the scope by 13.6 degrees and then hit plate-solve again, it gave another 13.6-degree error. The error appeared along the azimuth only. Has anyone seen this problem, or does anyone have an idea what may be causing this error? Thank you.

[admin]

Hi,

I haven't seen anything like that before. Could you share a SharpCap log file that shows the error happening please so that I can investigate?

I would also suggest checking the latitude/longitude settings for your ASCOM GOTO mount and also the time setting on both the mount and the computer - it's possible that these being in error or having different times set could cause all sorts of interesting issues with co-ordinates.

thanks,

Robin

[jabbourk]

Log_2024-07-31T20_57_25-6364.log

(531.43 KiB) Downloaded 81 times

Robin:

Thank you. I attached the logfile from last night's session.

Kamal

[jabbourk]

Robin:

If you search the logfile for "Plate solve succeeded" you get seven matches, all with very large errors. In the case of M57, I was staring at the ring in the middle of the frame when "Plate solve succeeded" indicated an error of 13-some degrees. I cancelled the sync, and proceeded to stack a dozen frames.

Kamal

[admin]

Hi Kamal,

that's odd - looking through the log, all the positions are out by roughly 1 hour of RA (which is 15 degrees) - the mount seems to be reporting back an RA that is 1 hour lower than the actual position. For instance...

Code: Select all

// you run a sequence to move to the ring nebula
Debug  	21:19:57.124711	#1 	Sequencer : Completed : Move the mount to (RA,Dec) RA=18:53:35.0,Dec=+33:01:42 (RA=18:53:35.0,Dec=+33:01:41)			
Debug  	21:19:57.126339	#1 	Sequencer : Starting  : Set imaging target name to 'NGC6720 (M57, Ring Nebula)'											

// you start plate solving a bit later
Debug  	21:28:47.748222	#1 	Notification (Status=Warning): Solving frame... Please wait...															
Info   	21:28:47.765145	#1 	Before plate solving mount points to RA=17:58:08.0,Dec=+33:03:46														

// plate solving results show the correct co-ords for the ring nebula (give or take a bit)
Info   	21:29:49.761348	#1 	Plate solving : Field center: (RA H:M:S, Dec D:M:S) = (18:53:45.025, +31:56:57.818).									
Debug  	21:29:49.761921	#1 	Notification (Status=Warning): Solving: Field center: (RA H:M:S, Dec D:M:S) = (18:53:45.025, +31:56:57.818).			

// even after being told that it is pointing at RA=18:53:.., mount still reports 17:..:..

Info   	21:29:49.899629	#1 	Mount reports JNOW, converting results position from RA=18:53:45.0,Dec=+31:56:57 (J2000)	
Info   	21:29:49.901013	#1 	Conversion result is RA=18:54:41.9,Dec=+31:58:53 (JNOW)										
nfo   	21:29:49.910488	#1 	Field solved to RA=18:54:41.9,Dec=+31:58:53, field Size {Width=0.19924, Height=0.1332735}	
Info   	21:29:57.675231	#1 	Before Sync mount is at RA=17:58:09.0,Dec=+33:03:47											
Info   	21:30:00.954130	#1 	After Sync mount is at RA=17:58:17.0,Dec=+31:58:59											
						

I think that the underlying cause here is something odd going on with your ASCOM driver, and if there is a cure it will be in the settings for the 'Meade Generic' driver. I don't have any Meade kit to test with, but general troubleshooting would be to check that the ASCOM driver is the latest version, review any options, check location and time settings (particularly daylight saving time as the positions are 1 hour out).

You can confirm the operation of the ASCOM driver by turning on the option to log 'Mount Hardware Communication' in the SharpCap logging settings before opening the camera/mount - that will cause SharpCap to log communications with the ASCOM driver into the SharpCap log and you will see entries like...

Code: Select all

Verbose 14:25:57.455996 #26 Mount : SharpCap.MountProxy.ASCOM.IMountInterceptionProxy.get_RightAscension :: Starting get_RightAscension()
Verbose 14:25:57.456243 #26 Mount : SharpCap.MountProxy.ASCOM.IMountInterceptionProxy.get_RightAscension :: Completed (returned 10.188482372436908) get_RightAscension()
Verbose 14:25:57.466993 #26 Mount : SharpCap.MountProxy.ASCOM.IMountInterceptionProxy.get_Declination :: Starting get_Declination()
Verbose 14:25:57.467212 #26 Mount : SharpCap.MountProxy.ASCOM.IMountInterceptionProxy.get_Declination :: Completed (returned 5.6666666665705634E-05) get_Declination()

which show the values reported by the ASCOM driver when SharpCap asks for the current RA and Dec positions of the mount. I strongly suspect that these will turn out to be 1 hour out in alignment with the 1 hour out in the other log entries above.

cheers,

Robin

[jabbourk]

Good morning Robin:

Thank you very much. I will turn on mount debug logging, and check thoroughly the Meade driver. Subject telescope is a 16-inch Meade GPS in a large observatory at SUNY Oswego. I will report back in a few days.

Kamal

[jprudente]

I'm having this same issue - 13.6 degrees off whenever I platesolve. I have a AVX mount using ASCOM drivers also.
Have you found the issue?

[admin]

Hi,

sorry, no - I didn't receive any further feedback from the original poster as to whether they had found the cause or not. Looking again, one thing worth checking is the date/time/timezone/daylight saving time settings on the handset. The handset thinking it is in daylight saving time vs the PC not might account for a 1 hour out RA position.

cheers,

Robin

[jabbourk]

Sorry I did not report back when I found the problem. The issue was with the azimuth mount lock - it was loose just enough. Tightening the lock and re-aligning the mount solved the issue.

Robin - a big THANK YOU for all you do for the astrophotography community.