| 3 | 5 | In light of continuing confusion on the psphot background measurements, I performed a series of tests to verify the consistency and possible error sources of the sky levels from the raw to stack stages for the 12-input test stack for MD04/skycell.055 from exposures (o6538g0139o,o6540g0157o,o6540g0213o,o6543g0266o,o6550g0059o,o6558g0328o,o6567g0066o,o6569g0065o,o6569g0073o,o6569g0081o). These exposures were chosen to match the test stack Peter made. All IPP processing was done using the standard processing recipes, although with the random seed fixed to the value 1234. This ensures that differences due to pixel selection are removed. In addition, each processing stage was repeated both with the standard quantized integer output images as well as floating point uncompressed images. Image histograms were performed in MANA, using a fixed 0.25 bin width for all images. RAW and CHIP stage images had pixels with any masked bits replaced with NAN values, and were therefore removed from further consideration. WARP and STACK images did not have this operation performed, as they have bad pixel data replaced with NAN before being written out. Non-IPP Gaussian fits were run on these histograms, with all unpopulated and end point bins removed. MANA assigns points outside of the histogram range to these bins, which were chosen to be sufficiently far from the sky distribution to be influential (RAW: +/- 10000, CHIP/WARP: +/- 100, STACK: +/-2000). |
