Option to extract TG as full-size (1x1) images?
Stacking program, astrometric (plate) solver, fits file viewer
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I did a test where I extracted TG using Pixinsight, which generates full-size (1x1 binned) images. Then I did the same using ASTAP, which generates half-size (2x2 binned) images. After TG extraction, the FITS files in each of the two sets of images were stacked in groups of ten. ASTAP successfully did photometry on almost 80% (46/58) of the full-size images, but just 31% (18/58) of the half-size images.
The telescope was a Seestar S30 Pro. Part of the issue is that images were perfectly focused.
The graph that shows TG extracted using ASTAP
Hi Andy,
Extracting TG full size from a Bayer patter image is technical impossible. I do not know how PI modified them , but I think it better to improve the detection of the stars using the half size images. Can you share the half sized TG series for a test here?
Perfect focus is not so good since the peak of the star can be at the red or blue sensitive pixel which is removed later. A little defocus is normally better.
cs, Han
Last edit: han.k 1 day ago
Pixinsight uses bilinear interpolation to fill in the missing TG values at TB and TR pixels. Separately, I have sent you a link to the ASTAP stacked images used for the ASTAP photometry. Thank you!
Hi Andy,
I found the problem and have a fix.
There is a faint star very near to KR_Cyg. It spoils the auto center. Just activated the option "Disable star autocenter". It will then rely on the astrometric position rather then autocenter. See red mark annotation i attached screenshot.
Use the half sized images. Not the PI.
cs, Han
It works beautifully now, even with a smaller 2.0 (xHFD) aperture! All 58 stacked images give 58 magnitude values and a nice-looking light curve. (attached) My faith is renewed, and I am most grateful. I must remember to disable star autocenter in cases like this, and to inspect images more carefully. Thank you, Han!
Best, Andy