Verification Datasets Meeting 2016-04-13 Minutes

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Verification Datasets meeting
Attendees: Colin, Simon, Hsin-Fang, David, Zeljko
Regrets: Angelo

Colin:

  • manually classifying diff im sources, illustrative
  • good idea of how many false positives, how many are real how many are junk
  • a lot of them look real, lots of rectangles, 1-2 columns of pixels have a short little bar
  • maybe 50% are real, still need to add all of them up, a few hundred false positives per square degree
  • just on moving object, excludes cases where there is an object detected in both visits

Simon:

  • no update on twinkles
  • working on ISR this week, xtalk, linearity and fringing need to brought in from HSC
    • for example, HSC talk has hard-coded values, need to make it general

Zeljko:

  • working on DPDD

Hsin-Fang:

  • no updates
  • spent some time looking through Jim’s Level 2 flowchart

David:
https://confluence.lsstcorp.org/display/SQRE/COSMOS+DECam+data+reduction

  • trying to dig down into why the cosmos photometric scatter of individual objects over multiple visits
    is larger than expected
  • looked at relative fluxmag0 variations versus ccdnum, there are persistent chip-to-chip variations but they are only at the ~1-2% so not enough to explain the scatter of individual object photometry over multiple visits
  • Simon suggested plotting fluxmag with radius of focal plane, maybe vignetting
  • Simon suggested cutting on flags, cut on saturation flags, cut on extendedness parameter, something close to 1
  • Colin also suggested, psf-aperture also does a pretty good job
  • David, maybe throughput changes spatially with the filter
  • will dig into this some more

No verification datasets meeting next week, David will be in Pasadena. We will pick up again on April 27th.