Plate solving failure using ASI120-color with guide camera
Stacking program, astrometric (plate) solver, fits file viewer
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I have had a very frustrating time trying to plate solve images from a ASI120MC color camera on a 240 mm F/4 guide scope. Could it be that the FOV at 68' x 50' is too small? I got the following error message:
10:22:22 Creating grayscale x 2 binning image for solving/star alignment.
10:22:22 █ █ █ █ █ █ Warning, remaining image dimensions too low! Try to REDUCE OR REMOVE DOWNSAMPLING. Set this option in stack menu, tab alignment.
10:22:22 139 stars, 110 quads selected in the image. 104 database stars, 82 database quads required for the square search field of 0.8°. Search window at 200%
10:22:23 No solution found! :(
The down sampling was already set at 0. The file size of the raw image is 2.4 mb, but after binning to 2x2, it is just 0.6 mb.
If I submit the image to Astrometry.net, it solves successfully.
I have been able to successfully plate solve using ASTAP with my Canon camera, but of course it has a much larger field of view, about 4 deg by 3 deg.
Rick,
68' x 50' is fine
Down sampling x2 is very bad for solving if your image is 1280 x 960. Downsampling 0 is fine. I assume is is forced by the acquisition program your using. By which program is ASTAP executed? Check the setting in that program
Han
Perhaps I did not explain properly. I was operating ASTAP directly, not through another program. I had the down sampling set to 0. Perhaps because the image was a color image, ASTAP did the 2x2 binning, which perhaps made the image too small as reported in the error message I copied in my post above.
If the image is 1280x960 pixels it will not down sample. Can you attach the FITS file for testing?
The attached file was solved by Astrometry.net in about 10 seconds, but could not be solved by ASTAP. As I said above, it started as a color image, it was calibrated with a master dark and a master flat, deBayered, then converted to mono, all within ASTAP. Settings were Downsample 0, max stars 600, Hash code 0.005, Ignore stars less than 2; FOV height 0.84, database used H18; slow=yes.
ASTAP detects 20 stars and some hotpixels. The hotpixels can be filtered but 20 star is in this case not enough ASTAP requires about 30 stars to solve reliable.
Debayering is normally not good for solving. In tab "stack method" there is one button called "test normalise flat" which could help to equalise the bayer pattern, but it not automated.
The only thing what would help is to expose longer and have accurate focus. Else you have to rely on Astrometry.net.
Han
See screenshot
Thanks for your review and advice.