Project: datamanagement
Issue DM-6491: Investigate offset in baseline zeropoint between LSST vs. HSC stack reductions for some HSC visits
DM-6490 reports on an offset between the calibration zeropoints between HSC vs. LSST *processCcd.py* runs. Here we report another, additional, offset seen in certain HSC visits. It is not seen in the figures shown in DM-6490 for visit 1322. However, here attach the same figures for visit 19696, run with identical setups/configs for both stacks as in DM-6490, where we see an additional offset in the "common ZP" figures (i.e. all fluxes have been scaled the same zp=33.0 for comparison). A best guess at present is that the calibration frames are different between the HSC and LSST stacks for the timeframe of this visit; e.g. were the inputs ingested exactly the same for both sets? Did the bug in regards to flagging on the flats noted in DM-5124: {quote} I found a difference in the codes doing the statistics: the HSC code uses a hard-coded mask ignore list of DETECTED only, while the LSST code uses a configurable mask ignore list that defaults to DETECTED,BAD (and the default isn't overridden). This produces a large difference on CCDs with bad amps (e.g., ccd=9). There's a smaller difference on ccd=49 because the number of BAD pixels is smaller. Also note that the scaling of one CCD (like ccd=9) can affect others because we force the normalisations to correspond to that which we get from solving the system of M exposures of N CCDs. {quote} have a greater impact on these calibs? Please investigate the cause of this offset.
Story points: 8