Plate Solving Problem

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muzastro
Posts: 2
Joined: Wed Aug 10, 2022 8:45 am

Plate Solving Problem

#1

Post by muzastro »

Hi all,

I’m very new to astrophotography and recently purchased SharpCap - one reason being that I like the ability to plate solve within the capture software.

I am struggling to get plate solving to work, however. I use All Sky Plate Solver within Sharpcap and I will play around with the settings typically so I can see maybe 5-10 stars and the plate solver says it has found around 50-60 sources.

The problem is that very rarely am I able to successfully plate solve, and I’ve only ever managed to plate solve twice in one night once.

Recently, when a plate solve failed, I took a snapshot of the exact same framing and uploaded it to astrometry.net. The image was solved almost right away. Furthermore, I then downloaded the FITS file output from astrometry and opened it within the standalone All Sky Plate Solver. The image was solved in around 30 seconds.

I’m not sure if I’ve set up the plate solver incorrectly or something else is going on - but the fact that (on a rare occasion) I can plate solve, leads me to think something else may be occurring.

Has anyone else ran into this issue and managed to resolve it?

Thanks
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admin
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Posts: 13173
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
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Re: Plate Solving Problem

#2

Post by admin »

Hi,

if you can only see 5-10 stars then it may be that your images are a bit dim - try increasing gain or exposure a bit to see if that helps. The optimum number of stars detected for ASPS seems to be in the 100-200 range, so aim for that either by changing gain/exposure or the 'Sigma' setting.

Note that there is an option about sending 8 bit images to the plate solving enging in SharpCap - do try with this set both on and off - it seems to work nicely for some people with it switched on but causes problems for others.

If still no luck then please share one of the images you captured and your SharpCap log after attempting to plate solve and I will investigate further.

thanks,

Robin
lowenthalm
Posts: 143
Joined: Mon May 07, 2018 12:27 am

Re: Plate Solving Problem

#3

Post by lowenthalm »

I have found when using the ASTAP plate solver that using 8-bit images in Sharpcap's plate solver settings does help. I have also found that turning on simple offset background subtraction helps enormously. I now default to always setting this mode when plate solving - this might be a good thing to have Sharpcap do internally automatically when doing a plate solve. If the plate solver continues to be troublesome, doubling the exposure or, paradoxically, sometimes halving the exposure can help too.
muzastro
Posts: 2
Joined: Wed Aug 10, 2022 8:45 am

Re: Plate Solving Problem

#4

Post by muzastro »

Thanks both for your suggestions.

Tonight should be clear so I will try them out later.

If I run into the same issue, I will ensure to post all of the relevant pictures/ screenshots in my next post.
captaincook
Posts: 5
Joined: Fri Aug 13, 2021 7:33 am

Re: Plate Solving Problem

#5

Post by captaincook »

Dear Robin,
My plate solving has suddenly stopped syncing with my mount. It solves OK and brings up the reported position, says it is moving the mount but then fails to do so. I activate the solve and sync mode from the telescope controls and it is set that way in the settings menu (I havent changed anything and it worked fine for 12 months prior to this week).
Please can you suggest a fix as I am totally stumped!
BW
Gary
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admin
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Re: Plate Solving Problem

#6

Post by admin »

Hi Gary,

it's probably best to post the SharpCap log from a session where the error happened (which will contain all the info necessary to work out what is going on, including any error messages). However, one thing that can cause problems is that some ASCOM drivers reject the sync command if the difference between the current position and the plate solved position is too large (more than a few degrees). If your alignment is a long way out to begin with for some reason then that might be happening.

cheers,

Robin
Darksky001
Posts: 1
Joined: Fri Jun 16, 2023 2:53 pm

Re: Plate Solving Problem

#7

Post by Darksky001 »

Hi,

I'd like to report I have the same issue, never really had a problem with it, even when my alignment was out. Its been working well for about 6 months.

However I recently upgraded to the latest version of the skywatcher app, (Pro 2.3.8) along with their Ascom drivers.
I'm also running sharpcap v4.0.9562.0

Prior to this, I was also forced into some Win 10 update.... I do hate that feature.

Plate solve appears to work, and it knows its location based on the image. The platesolve to mouse cursor also seems to work.
But platesolve and sync does not.

The platesolve part works, but the mount doesn't move.
But the direction keys, and the click to centre plate solve all move the mount fine.

I had the issue last night on Caldwell 9.

According to the logs, I was off target by 0.87 degrees.
It certainly logs RA and Dec to that effect. But appears to send the sync commands, and the mount doesn't move.

Just informing the group really, in case there is a bigger issue.

Cheers,

Matt
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