Plate solving?

Discussions of using SharpCap for Planetary Imaging
devonshire
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Plate solving?

Post by devonshire »

I'll be upgrading my guide camera shortly, and this will free up my GPCAM2 IMX224 for planetary work w/Sharpcap, as opposed to BYN + D5300, which I've been using on DSO's.

One of the things I use on every DSO session with BYN is the plate solving integration w/Astrotortilla. Very nice, both for finding and framing the targets after CdC gets me close.

Although I currently use Sharpcap only for PA, I do understand that it can plate-solve, and I hope to get that working as part of controlling the IMX224 in its planetary imaging role (Imaging scope: EDT refractor, 102/621mm, assume barlowed for planetary).

BUT... what I'm not clear on is how best to use that for framing, when my target is a planet. Pick a nearby star? Advice?

Thanks!

- Bob
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Re: Plate solving?

Post by admin »

Hi,

That might be tricky because when you are imaging the planets your field of view tends to be very small, which means there may not be enough stars for the plate solving algorithm to work well.

It will turn to be worth a try though... Just tell your planetarium software to go to the planet, then use the plate solver and re-sync button in the telescope controls in SharpCap – first making sure you can see 20 or so stars in the frame which will properly need you to set high gain in a few seconds of exposure at least. As long as you've got the data installed on AstroTortilla for small fields of view and enough stars are visible then the plate solving should locate where the telescope is pointing and then correct the pointing to bring the planet in to view. I must admit though that I've never tried this with a planetary camera/scope setup.

Cheers, Robin
devonshire
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Re: Plate solving?

Post by devonshire »

Thanks, Robin!

Well, it is all about FOV, however one centers, isn't it? :-)

Which indexes did you have in mind for this? :
"As long as you've got the data installed on AstroTortilla for small fields of view..."

- Bob
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Re: Plate solving?

Post by admin »

Hi,

When you install AstroTortilla, it asks you about installing the index files for different fields of view – the smaller the field of view you want to cope with the more data needs to be downloaded and installed. If you want to add more index files for smaller scales then I think you can just run the installer again.

Cheers, Robin
BlackWikkett
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Re: Plate solving?

Post by BlackWikkett »

Here's an excellent Astrotortilla installation and setup guide. It's a few years old but still relevant.
https://www.lightvortexastronomy.com/tu ... lving.html
TimHaymes
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Re: Plate solving - which solver ?

Post by TimHaymes »

I'm posting a reply here as i dont seem to be able create a new topic, but the subject is similar. I believe I have plate solving working now. In the process of testing I have two solvers installed. All SkyPlate Solver (ASPS) and Astrometry.net Local Server which has ansvr. Both apps have there own set of index files. When I set up SC plate solve settings i use AstroTortilla/Ansvr/ASPS as the preferred plate solver.

The question: If SC is using one or other of the two solvers installed, and how do find out which it is ?

Looking at solve field tool setting, the automatic detect is: c>users>Tim>Appdata>Local>Astrometry>bin>solve-field
Is this All Sky Plate Solver ?

The most positive outcome of the solved field are the OBJ coordinates, which are written to the FITS file header - very helpful.

Tim
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Re: Plate solving?

Post by admin »

Hi,

in the current version the best thing to do is to perform a plate solve and then look in the log to see what the path to the plate solving application was (search the log text for "running external command").

I've seen a number of issues recently where people have had trouble because their plate solving application setup is complex or incomplete, so I have enhanced SharpCap to provide more details in the plate solving settings and to also check for common problems (no index files, out of date Astap version, etc). This will be in the next update SharpCap 3.2.

Cheers, Robin
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Calamity_Jane
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Re: Plate solving?

Post by Calamity_Jane »

I think I am getting the idea here. Somehow I had never heard of plate solving until a friend recommended it to me the other day. (Where have I been? Good question.)

Anyway I have Sharp Cap Pro, fully updated, and use it to control a ZWO ASI294MC Pro (i.e. cooled) camera. My mount is a Celestron CGX and my scope is a Celestron C11 XLT. I can control it via Celestron's CPWI software. It's all permanently installed in a little observatory.

If I download Astro Tortilla, should I be able to hook it all up and plate solve? Is there anything else I need to do, please?

Thanks,

Jane.
TimHaymes
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Re: Plate solving?

Post by TimHaymes »

This topic has been aired on SC forum many time, and ive learned a lot but im not an expert. Permit me to give some pointers. I have a C11 on EQ8 controlled by EQMOD through PC direct mode.
The mount has been polar aligned via SC tool. I find that a plate solve will add RA/DEC to FITS headers, so this a plus. My solver is ASPS, and i found it more convenient to set up, and may be works better. When Plate solve software is installed, a large amount of reference data is downloaded. For longer focal lengths and narrow fields the file sizes start to get big but they are needed. I find ASPS is good for checking which files you have downloaded because at some point you may want to know, and the overall GUI is cleaner in my opinion.

The solver will need some info to help it - The camera field of view (mine is 0.25 deg) and possible an indication of how far the solver should search.
Another factor is the number of stars it needs for a successful solve. I think this is 100 to 200. I find an exposure of 1 to 5 sec will do this. My solver reports 950 stars !

In sharpcap settings, open the Plate solve tab. I have "Sync mount and re-center target" as the operation after solve and the path to the solve files set to automatic. The window at bottom tells you what files are being used which is helpful to check the solver installation.

In the SC camera control, bottom RHS is window that will open up and connect to the mount. This needs to be open, and there is a radio button to click on. This will start the solver, and hopefully it will work ;-). Its takes about a minute for my setup.

Best of luck
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Re: Plate solving?

Post by admin »

Calamity_Jane wrote: Wed Oct 13, 2021 10:55 am I think I am getting the idea here. Somehow I had never heard of plate solving until a friend recommended it to me the other day. (Where have I been? Good question.)

Anyway I have Sharp Cap Pro, fully updated, and use it to control a ZWO ASI294MC Pro (i.e. cooled) camera. My mount is a Celestron CGX and my scope is a Celestron C11 XLT. I can control it via Celestron's CPWI software. It's all permanently installed in a little observatory.

If I download Astro Tortilla, should I be able to hook it all up and plate solve? Is there anything else I need to do, please?

Thanks,

Jane.
Hi,

sounds like you are on the right track - some things to remember

* Installing the right index files for AstroTortilla - you can re-run the installer if you want/need to add more.
* Installing the latest SharpCap 4.0 - there are lots of plate solving improvements in SC 4.0 over version 3.2
* Using the 'test' button in the SharpCap plate solving settings - this runs a sample image (with a field of view of about 1.25x1 degree) through the plate solver to check it is working correctly
* When using for real, check that you can see stars on screen without using display stretch
* Once you have plate solving working correctly for your scope/camera, check out the 'double click to recenter' feature - https://docs.sharpcap.co.uk/4.0/#Pixel% ... 20Recentre

cheers,

Robin
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