ASTAP plate-solve - focal-length units

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ChrisR Oz
Posts: 22
Joined: Tue Sep 28, 2021 11:03 am
Location: Melbourne

ASTAP plate-solve - focal-length units

Post by ChrisR Oz »

Armed with the Sky Simulator working with ASCOM mount and focuser simulators (the lengths we go to, to see something when it rains every day), I wanted to try the plate-solving in SC 4.0.

Firstly, AstroTorilla install fails to provide the solver exe. I think it's a permissions thing, based on another post, that prevents installing the solver exe in an ADMIN account, which is weird. So I try ASTAP, which works fine, tested stand-alone using the simulated star fields from Sky Simulator. It was quite sensitive to having a good estimate of FOV provided.

Now try a plate-solve (solve only) in SC. This persists in failing. So I check the logs (great to have a program where you can instantly dive into logs without running it again in some "debug" mode). There I find an interesting mis-match in distance units between SC and the ASCOM .NET Telescope simulator. It passes a crazy large FOV to ASTAP because it thinks my scope has a FL of 2mm! It works if I set my scope details in the ASCOM Telescope simulator to FL=2025m, diameter=203m (guess I won't be packing that in the car). Then the log (see attached) reports this ...

Field of view calculated as 0.55x0.37 degrees based on FL of 2025.0mm and sensor size of 19.60x13.06mm

The ASCOM telescope simulator setup uses "m" for size of FL and diameter. However, SharpCap "sees" this FL as "mm". It's a case of confused understanding of units for these quantities.

Now the plate-solve works well, and I get confirmation of the (simulated) mount position.
Cheers, Chris.
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plate-solve2.log
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plate-solve.log
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Re: ASTAP plate-solve - focal-length units

Post by admin »

Hi Chris,

thanks for the report - that would be my mistake in not reading the ASCOM documentation properly :(

I have fixed this and the change will be in next week's update. At that point you will have to change your simulated 'Astonishingly Large Telescope' back to a normal focal length :)

cheers,

Robin
ChrisR Oz
Posts: 22
Joined: Tue Sep 28, 2021 11:03 am
Location: Melbourne

Re: ASTAP plate-solve - focal-length units

Post by ChrisR Oz »

Thanks Robin.

All back to normal again and working correctly with SC 4.0.8244.
Felt like I was on a large mountain top in Chile for a while ...

Thank you.
Cheers, Chris.
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