mariorpd13
commented
6 years ago Description of the problem: when @nivyaaroy runs 2dphot on KiDS DR1/DR2 images published in DR3, weird results are produced. The reason of that was tracked down to how the subsection science images are produced
In the plot below, you can see (from upper left, counter-clockwise), sections of: the full coadd, the science and mask subsections that @nivyaaroy produced. The sections were matched in pixels: the circles show the same WCS position, you can see that there is no issue in coadd vs. mask, while there is a problem in the science subsection
In the plot below I matched in WCS a larger area of coadd (right) vs. subsection (left). The circle now shows the position of the same source in both images, for reference. The weird thing is that in the subsection there is a region (in the left part) which DOES NOT appear in the coadd, and actually is a part of the coadded image translated to the first half of the image !
So, to summarize: there is an issue in the production of science subsections (masks are ok), as a consequence we are running 2dphot on the wrong pixels (and using mask informations from the right pixels). In addition, running listhead on the science subsection seems corrupted I get errors, which points to problems in the fits file.
To try to understand the problem, @mariorpd13 selected from the script that @nivyaaroy is using to run 2dphot, only those lines that produce the subsections. This is done in thor, using the same KiDS image used for the above tests: /thornas2/tig/KIDS_ESO_DR3/KiDS_DR1.0129.0-0.5_r_sci.fits. The script is: /home/radovich/test_kids/test_n.x. However, I CAN'T reproduce the problem: the science subsection produced by THIS script is ok (no pixel mismatch, no error in the fits file).
Since the subsection is produced with a modified version of the imhead code, it is possible that the issue is due to problems in the FITSIO library. so it should be checked if @nivyaaroy and @mariorpd13 are using the same versions of imarith/CFITSIO (@mariorpd13: /usr/local/bin/imarith, /home/radovich/pullecenella/program/cfitsio)
ctortora
FedorGetman
nivyaaroy
So, the question is: why are the two different, since they are produced using the same input images and the same code/libraries ??
KiaraSpin
AI @mariorpd13 -> can you please collect here all the problems and the checks that you did concerning this issue? We need a complete description of the problem including what has to be done and by whom?