Photometric calibration eventually succeeds, but globular cluster is monochrome

Software Siril
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I had a good evening two nights ago, and acquired 100 images of the globular cluster Omega Centauri.

I am still coming up to speed on Siril, and simply use the OSC script plus a simple set of directions I found online.

For most images, plate solving works, and photometric calibration produces great star colors.

But for my 1.5 degree wide image with huge Omega Centauri in the middle, most attempts at plate solving fail, even though it knows the object, and the coordinates are correct. Are globulars particularly challenging in that regard?

After a number of setting changes in the plate solving window, I eventually get it to solve, allowing me to do photometric calibration. This reports as having completed, but the result is pure white stars.

I also get warnings that I need to be in Linear mode, but I am in linear mode. I’m not sure what to do next. Log file post stacking attached; best to read up from the bottom
Siril log file plate solve color calibration.txt (21.9 KB)
. Thanks!

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Could you share your picture too? The stacking result.

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Thanks, but how would that be possible; the Result file is 716 MB. Would a compressed 12 MB JPG be helpful?

I also noticed a different odd bit. I normally have some vignetting in the corners, which the flats fix. This image had really dark corners, one of which was much bigger. In the result image, those dark corners didn’t go to flat with stars, they became bright white. Placing squares within them during Background Extraction in post helped.

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A jpg will not help. It is possible because a lot of file sharing website exist. WeTransfer for example.

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I’ll look into WeTransfer. Where would I be transferring it to?

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You just need to paste the link here.

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OMG!! All is now clear. I was in a hurry the other night, and as it happens, my ASI6200MC was mounted on a Sigma lens indoors, on a flat box, and what I took to the observatory was my ASI6200MM, a monochrome camera!! That sort of explains why photometric color calibration didn’t actually deliver any colors… Embarrassing. And that giant dark spot in one corner is almost certainly the Optec off-axis prism pickup, which was never phased as it should have been to lie along the short dimension of the sensor.

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