I love the photometric color calibration (PCC) option in Siril. When it works, it produces a very pleasant images with well balanced color on stars. The problem is “when it works”. I find that is extremely sensitive to a lot of details and we receive so little information about it (for example it never works for my short focal images)
Take for example, this image of M101 from Tadej Skofic (https://www.youtube.com/watch?v=RrZ5u5TaFlM). I’m trying to process it using Siril and as it has an important colour cast, my first option was to use the PCC.
So I selected M101 coordinates as the center of the image. For the image scale I’ve uploaded the image to Astrometry.net to plate solve and get the image scale. As you can see in the solution page (http://nova.astrometry.net/user_images/3496462) the image scale es 1.77 arctic/pixel so I have put a focal length of 1000mm and a pixel size of 8.58 to get the same image scale (1.77).
But when I try to solve and apply the color correction it failed with the generic error. Looking at the logs I don’t get any clue
fetch_url(): http://cdsweb.u-strasbg.fr/cgi-bin/nph-sesame/-oI/A?M101 initializing CURL fetch_url(): http://vizier.u-strasbg.fr/viz-bin/asu-tsv?-source=NOMAD&-out.meta=-h-u-D&-out.add=_r&-sort=_r&-out=%20RAJ2000%20DEJ2000%20Vmag%20Bmag&-out.max=200000&-c=0.000000+0.000000&-c.rm=74.6&Vmag=<12.32 log: Findstar: processing... log: Catalog NOMAD size: 145 objects using min_scale 1.569752 max_scale 1.969752 using trans_order 1 atFindTrans: iter_trans unable to create a valid TRANS Give another try with scale changes atFindTrans: iter_trans unable to create a valid TRANS initial call to atFindTrans fails using min_scale 1.569752 max_scale 1.969752 using trans_order 1 atFindTrans: iter_trans unable to create a valid TRANS Give another try with scale changes using trans_order 1. Initial trans structure: TRANS: a=-1.080093591e+03 b=4.654133693e-02 c=5.150562423e-01 d=-7.510087844e+02 e=7.510499296e-02 f=1.622294980e-01 sig=1.3793e-22 Nr=1 Nm=0 sx=0.0000e+00 sy=0.0000e+00 atRecalcTrans: only 1 stars in list(s), require at least 6 atRecalcTrans fails on matched pairs only log: Plate Solving failed. The image could not be aligned with the reference stars.
Any idea on how I can improve the reliability of the option?