Sequencer moves FOV away from centered target

[iKon308]

Problem: Use of Sequencer to capture subframes always moves the target offcenter or out of frame. I did not enable goto in the Sequencer.

Praise: Tool for goto target coordinate and re-center works brilliantly (I newly updated to the 22 Jan 24 version of SC).

Background: I like to confirm good framing of dim targets before capturing images, and am not yet confident in the plate solve/recenter function. I may have trust issues. ;^)

Question: Is this a bug, user error, or old issue resolved in the 5 Feb 24 version that i will try tonight?

PS: Robin -- thanks for making Sharpcap Pro my DSO capture tool of choice. I use PA, focus assist multi, goto/recenter, capture, and sequencer.

All the Best!
Dave Stokes

[admin]

Hi Dave,

glad that you are enjoying using SharpCap for your imaging

I think that to have a good chance of understanding what is going on here, I will need to see your sequencer setup that you are using and also know a bit more about what you have done before you run the sequencer. If you are using the 'Deep Sky Sequence Planner' then save your configuration as an 'SSP' file and share it here. If you are using the main sequence editor then you can share your saved 'SCS' file here. I might also need to look at the SharpCap log from the session where you had the issue, but it would be good to understand your sequencer setup first.

cheers,

Robin

[iKon308]

I ran the goto location and recenter tool, and Sirius was well centered. then ran simple DS Sequencer to capture 5 frames, and captured frames have star at edge in corner.

Ran into trouble attaching DSS and image files here. How to send the files?
Error: The extension ssp is not allowed
Error: The extension fits is not allowed

All the Best,
Dave Stokes

[admin]

Hi,

I have corrected the forum settings to allow SSP files to be uploaded - I've also allowed fit/fits files, but there is an overall size limit of 1Mb per file that will probably stop them anyway (this keeps the amount of storage needed for the forums and their backups down to a reasonable level). If you have larger files than 1Mb, the best thing is to upload to some other file sharing service (Google Drive, Microsoft OneDrive, Dropbox, etc), then post the sharing download link here in the forums.

thanks,

Robin

[iKon308]

Robin -- I updated to latest version of SC yesterday, and took it outside last night.

1. 'Goto catalog target/coordinates' command resulted in well centered Sirius in live view. Recenter usually adjusts position by 0.8-1.5 degrees.
2. subsequent 'Deep sky sequence planner' execution (specified that scope was already pointed at target) resulted in 5 well exposed images, but with Sirius in corner.

Sequence planner file and offcenter image are attached.

Rig is a C8 f/6, Orion Atlas AZ/EQ Pro mount laptop control via ASCOM and serial cable. FOV is ~ 45x30 arcmin.

All the Best!
Dave Stokes

sirius-after sequencer.jpg (3.37 KiB) Viewed 320 times

dstokes-sequencer-moves-fov.ssp

(1.34 KiB) Downloaded 19 times

[admin]

Hi Dave,

that's odd - there is nothing in your sequence plan that should make SharpCap move the mount at all (well, apart from dithering being enabled, but that would not do anything until at least 3 frames in, so not likely to be the cause).

I'm going to need to see the SharpCap log from the session where you captured this image - maybe that will reveal something. The only two reasons I can think of that the star might move are

1) the mount moves - but can't see what would trigger that
2) The camera settings are changed to either enter or leave ROI mode - again no evidence of that

The star is round in the image, so it is not drifting. It is probably something fairly simple that we just haven't spotted yet...

cheers,

Robin

[iKon308]

Hi Robin -- thanks for investigating.
SC log is attached (zipped, just over 1MB).

All the Best!
Dave Stokes
https://flic.kr/ps/3Qc1Ud

[CarCarlo147]

Hi Robin,
Without opening a new discussion, I report a problem with the Goto Catalog Target/Co-ordinates of version (4.1.11799).
With previous versions (4.1.11757) it works correctly.

I attach two images that show the incorrect alignment.
I would like to point out that the software settings are identical.

In practice, as you can see from the attached photos, it hits the target horizontally but not vertically.
Correct alignment

Immagine 2024-02-14 210411-1536x864.png (534.9 KiB) Viewed 264 times

Wrong alignment

Immagine 2024-02-14 210411 incorrect centering-1536x864.png (495.43 KiB) Viewed 264 times

[admin]

Hi,

thanks for the additional information - there were a number of changes in some of the astronomical calculations between those two versions to try to speed up the annotation tool with large custom databases, but the changes introduced by that were of the order of 1-2 arc seconds, so should not account for the shift. I will have to dig through the changes between those two versions carefully to see if anything else might have this impact.

It would be helpful to have the SharpCap logs for the two runs that produced the images above if possible - that would give me some more information to go on.

thanks,

Robin

[admin]

Ok, so I have had as much of a test as I can during daylight (I have a slightly tweaked setup here where I can test that sort of thing using ASCOM SkySimulator), and it seems to work in simulation. I recreated your orientation and field of view of the Monkey Head nebula and it ended up in the middle of view. Interestingly, the offset is exactly in the RA direction - about 2 to 3 minutes of RA (30 to 45 minutes of arc) out.

What option do you have set for the 'After solving...' action in the SharpCap plate solving settings? The default is to sync and recenter, but the alternative of an offset GOTO should work, but is known to be limited to one use after moving to a target - a second use will repeat the offset and move the target out of center.

cheers,

Robin