From firstname.lastname@example.orgTue Mar 25 09:37:53 1997 Date: Thu, 6 Feb 1997 13:24:49 -0800 From: email@example.com To: firstname.lastname@example.org Cc: email@example.com, firstname.lastname@example.org, email@example.com Subject: WG Mtg #114 Minutes IPAC 2MASS Working Group Meeting #114 Minutes 2/04/97 Attendees: R. Beck, R. Cutri, T. Evans, J. Fowler, L. Fullmer, T. Jarrett, G. Kopan, B. Light, H. McCallon, J. Rosenberg, S. Wheelock, J. White AGENDA 1.) 2MAPPS 1.0 2.) Pixel Linearity 3.) Chi-Square Improvement From Deblending 4.) Galaxy Photometry 5.) Association Parameters DISCUSSION 1.) 2MAPPS 1.0 Although the delivery for 2MAPPS 1.0 software is 5 February, R. Cutri stated that validation will require more than a few days of testing and requested suggestions for test scans. He listed the scans currently slated for processing by the new pipeline, all from 950503: six M67 scans, one Abell 26D5 scan, and five MSX scans. Suggestions for additional scans should be reported to R. Cutri. 2.) Pixel Linearity J. Fowler reported that some email discussions involving pixel linearity have taken place. Participants include R. Cutri, J. Fowler, E. Howard, G. Kopan, and M. Skrutskie. Past studies of nonlinearity were primarily concerned with soft saturation at high illumination levels, and the use of Read1 photometry alleviated such concerns. The new issue concerns deviations from linearity by several percent over the entire dynamic range. Possible nonlinearity calibration, correction, and monitoring techniques are being studied, primarily by E. Howard. The group concluded that until definite software modifications can be proposed, 2MAPPS will proceed independently of these considerations. It appears that the most likely impact would be in the RDFRAME module (maintained as part of the TAPELOAD subsystem and used by DARKS and DFLAT), where the process of converting data frames from 16-bit integer DN to 4-byte reals could be made to include a nonlinear transfer function. This would make the process transparent to the downstream software. There would also be operational considerations at the observatory (e.g., periodic special calibration procedures) and perhaps some offline analysis software at IPAC. Details await further study. 3.) Chi-Square Improvement From Deblending B. Light reported that the PROPHOT deblending algorithm reduces the chi-square figure of merit in the point-source extraction process, but currently the original chi-square value is not tracked by the system, and the point sources created by the deblending process are not associated unambiguously. He suggested that a new file be generated which provides this information, which might be useful for galaxy processing and should be included in the point source data base. The group decided that a separate file would be appropriate rather than additional columns in the main point-source file structures, since the latter would increase substantially in size with columns that are irrelevant for most sources. B. Light and T. Evans will work out a SIS for a file interface between PROPHOT and DBMAN. This file will contain information such as the original source ID numbers assigned by PROPHOT and the chi-square values before deblending and after each deblending step. 4.) Galaxy Photometry T. Jarrett reported that he and J. Rosenberg have just completed an extensive study of galaxy photometry. This study used SA57 scans in all three bands. A memo describing the study will be distributed very soon. 5.) Association Parameters T. Evans, H. McCallon, and R. Cutri have finished iterating the design of the updated catalog association parameters (see last week's minutes). H. McCallon will issue a new version of the POS05 SIS after the 2MAPPS 1.0 delivery activities have settled down. Since several subsystems will be affected by the SIS changes (GALWORKS/BFILL, QUALITY/CONMAN, CALMON, and DBMAN), and since the current POSPTS processor is a substitute that just transforms source coordinates from U-Scan to J2000, without making any catalog associations, the SIS changes will not be implemented until the real POSPTS is delivered.