Siril PCC Issue

My last three data sets have failed to calibrate using PCC. When running the operation, the log ends with the message “No valid stars found.” I’m running on a Mac, Big Sur 11.4 using Siril Any thoughts on why this is happening? Thanks for any help or guidance.

The most probable issue is that your stars are saturated. In this case, no photometry can be performed.

Thanks for your response, I very much appreciate it. The histogram is all the way to the left (not to the right). While there is always a green spike around 65k on the histogram (the Max), the Minimum and Average are down in the 3500-5000 range. I haven’t had problems in the past and haven’t changed any of my own procedures. I did upgrade to this version of Siril not long ago, perhaps there is a setting somewhere I could try adjusting?

Yes. But histogram shows you mainly dark areas. Saturated stars represent a few pixels so it is not visible. Other possibility is that stars have some black pixels.
In fact, photometry is impossible in two cases, easily understood.
1 - at least one pixel is saturated in the star (don’t forget that your DSLR has 12/14bits dynamic range, i.e for 12bits the maximum is reached at 4096 ADU)
2 - at least one pixel is totally black in the star

Of course this concerns stars found bith in the pic AND in the photometry catalogue. We can’t apply photometry for stars not in the photometry catalogue.

If no valid star are found, forget PCC, use the manual color calibration tool.

Got it, thanks! I think that the answer may be that the stars are not in the photometry catalog (although my stars themselves could be the problem, I suppose). I’ll keep all these things in mind next time I’m targeting and see how it turns out. Thanks again, so much!

That would be surprising because NOMAD catalogue contains 1.1 billions of stars.