Platesolving problem

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Posts: 2
Joined: 06 Jul 2019, 21:50

Platesolving problem

Post by pmilford » 06 Jul 2019, 22:06

I have been having some problems with platesolving, so I thought I would attempt to use ASTAP.

I'm using APT for data collection, 11" SCT f/10 with Canon DSLR T3i, astromodified.
Nominal focal length of telescope is 2800mm, other tools reporting 3122mm focal length.
Using correct focal length has helped greatly. Image is 0.28"/pix [24.55x16.37"]

Attached is an image of M8 that I can't seem to get ASTAP to solve. It has solved with both ASPS and Platesolve2.

I've been using the ASTAP UI rather than via APT to get things running.

I did successfully solve an image captured from my guidescope/guide camera, which is in .fits format
and larger FOV

From the difference in image preview at start of solving between guidescope and DSLR- no stars
highlighted, I'm thinking that the downsizing or conversion from jpg
to monochrome might be causing image scale issues in the solver??

Hope you can find the solution - ASTAP sounds like a good solution for platesolving!
L_1087_ISO800_40s__86F.JPG (4.23 MiB) Viewed 5752 times

Posts: 236
Joined: 23 Nov 2017, 15:04
Location: The Netherlands

Re: Platesolving problem

Post by han.k » 07 Jul 2019, 00:48

Hello Peter,

I tried to solve your image but could find a setting to do it. that the image is converted to mono is better. Downsampling of a factor 2, 3 or maybe 4 is required.

Using the option CCD inspector or show button tetrahedrons you will see that maybe half of the stars are ignored. The program sees them as galaxies of double stars.

A focal length of 3000 mm is long. If possible, could you try to improve focus and expose a little longer? Your image is due long focal length and seeing highly oversampled. So stars are 30x30 pixels.

Send me the next picture so I can have a new look to your images and problem.

Clear skies, Han

Posts: 2
Joined: 06 Jul 2019, 21:50

Re: Platesolving problem

Post by pmilford » 07 Jul 2019, 01:33

Looks like tonight will be overcast, so may take a few days for another image.

Fyi, I have this image solving now with both ASPS (I think the correct focal length is main
thing that helped)
And with Platesolver2 (2.28) which I think also benefited from correct scaling, along with relaxing star size.


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