IPAC 2MASS Working Group Meeting #89 Minutes

IPAC 2MASS Working Group Meeting #89 Minutes, 3/12/96

Attendees: R. Beck, T. Evans, J. Fowler, L. Fullmer, D. Kirkpatrick, G. Kopan, B. Light, H. McCallon


  1. PS CDR Dry Run
  2. Flattening Problem
  3. Seven-Apparition Photometry


  1. PS CDR Dry Run -- A dry run for PS CDR presentations will replace the regular working group meeting next Tuesday, March 19, but it will begin at 2:00 PM instead of 3:00 PM. J. Fowler requested that all subsystem cognizant engineers prepare the following information about the status of their development work as of next Tuesday: percentage completion of subsystem design, documentation, coding, and testing; it is preferable to break down all four categories by functional task, i.e., if a subsystem does functional tasks A and B, and coding of A is basically finished while B is hardly begun, the status should be reported as (e.g.) A 95% coded and B 5% coded, rather than the subsystem being 50% coded. For example, BANDMERGE initialization and input processing is 100% coded, the cross band connection processing is 98% coded, the inconsistent linkage correction processing is 0% coded, and the refinement and output processing is 0% coded. Status reports for the BANDMERGE design, documentation, and testing will also be broken down into these processing tasks. The breakdown should be fairly high level and meaningful to science team members. In some cases, such a breakdown may not be applicable; whether it applies to a given subsystem is left to that subsystem's cognizant engineer.

  2. Flattening Problem -- A flattening problem has been found in a scan being used for galaxy development by T. Jarrett; this problem has been found before, and a search for its solution hasn't yet had a high enough priority to be allocated resources. It appears that persistence due to a bright source contaminates the trimmed averaging in DFLAT, causing the persistence signature to get into the sky offset correction frame itself, from where it spreads the contamination to the frames in the domain of that correction frame. Assuming this is the problem, a solution was suggested by G. Kopan: use the nonlinearity detection code in DFLAT to identify the bad correction frame and mask the corresponding pixels in that frame, forcing DFLAT to use a correction based on averaging over the entire scan. J. Fowler will check the DFLAT code to see if this is a capability that can be turned on or requires code modification.

  3. Seven-Apparition Photometry -- B. Light presented some intermediate results in a study of whether aperture photometry is significantly improved for seven apparition point sources when all seven apparitions are used, as opposed to using only the first six. The results graphed showed no significant improvement when all seven apparitions were used, but the seven apparition statistics were diluted by being averaged with cases in which seven apparitions were in principle possible but one was excluded because of dead pixels or proximity to the edge of the frame. Whereas one would expect the S/N of seven apparition results to be better than six apparition results by the square root of 7/6, it is not clear that the nonuniformity introduced is worth the slight gain in a few cases.