From firstname.lastname@example.orgFri May 23 10:30:46 1997 Date: Wed, 7 May 1997 15:07:03 -0700 (PDT) From: email@example.com To: firstname.lastname@example.org Cc: email@example.com, firstname.lastname@example.org, email@example.com Subject: WG Mtg #121 Minutes IPAC 2MASS Working Group Meeting #121 Minutes 5/06/97 Attendees: R. Beck, T. Chester, R. Cutri, D. Engler, T. Evans, J. Fowler, T. Jarrett, B. Light, J. Mazzarella, H. McCallon, S. Wheelock, J. White AGENDA 1.) Processing Status 2.) Review Schedules 3.) Observing Resumption 4.) PSFs 5.) Hot Pixels 6.) Repeatability Analysis of Three-Channel Data DISCUSSION 1.) Processing Status R. Cutri reported that the 2MAPPS processing of night 55, otherwise known as 970423, was scheduled to begin as soon as the meeting ended. This run will use the new DARKS subsystem to force off certain hot pixels (see item 5 below) in the masks and also to force off pixels turned off by DFLAT in the 970418 processing (mostly pixels along the edge of the arrays). The data from this night have never been input to 2MAPPS before, so this run will also be something of a test of how the system reacts to never-before-seen data. 2.) Review Schedules R. Cutri announced that the next Science Team Meeting will be held at IPAC on June 4 and 5 and will be primarily an Operations Readiness Review for the Observatory, although some discussion of 2MAPPS status will take place on the second day of the meeting. For this purpose, subsystem cognizant engineers are requested to send information concerning subsystem status and liens to R. Cutri by May 14. The External Review Board Meeting will take place in Amherst in the second week of July. 3.) Observing Resumption Data will begin to arrive from the Observatory next week as observing resumes. Engineering tests are planned to support studies of the Read1/Read2-Read1 offset and repeatability, dithering pattern adjustments, electronic noise (the cabling has been rearranged to reduce this), drive gear problems, and flexure. A resident observer has not yet been hired, and so three IPAC personnel will be taking turns doing two-week stints in this position. This includes R. Cutri, H. McCallon, and Brant Nelson, a newly hired postdoc from UCLA. The observatory will be shut down for the month of August, and a permanent resident observer should be hired by the time activity resumes after that. 4.) PSFs Point-Spread Functions (PSFs) have been computed as a function of focal-plane position for all bands from one dense scan (041) and separately from a concatenation of sparse scans in 970418. The only differences between the dense and sparse cases was due to lower sample volumes from the sparse scans. The variability over the focal plane appears negligible in all bands, although a very small systematic effect appears to be discernible. The PSFs in J and H are round and sharp, but those in K are a bit elongated in the cross-scan direction. This may not present a problem, since the repeatability appears to be very good. Subsequent analysis of the PSFs in scan 044 shows that the K PSF is more compact and round than in either scan 041 or the low-density scans. 5.) Hot Pixels The "hot pixel" analysis has revealed that seven pixels in K are extremely erratic, i.e., they appear to generate electrons spontaneously at random times for periods of about 10 or 20 seconds. These seven pixels were found to be erratic on every scan that was studied by J. Mazzarella using a utility program especially written for this purpose by G. Kopan. In addition, another 48 pixels in K and one in H exhibit this behavior at a lower frequency, i.e., not in every scan studied. The new version of DARKS allows a pixel list to be specified for forced masking, and tonight's run will use this to turn off the seven worst pixels in K. In addition, J. Fowler will clone the PSF program and modify it to print out frame snips centered on hot pixels so that some insight into the shapes can be gained. It is hoped that this might lead to a good way to distinguish the hot-pixel syndrome from persistence due to bright sources, in case some method of automated detection turns out to be necessary. It is hoped that offline analysis and forced masking will suffice. 6.) Repeatability Analysis of Three-Channel Data R. Cutri displayed results from a repeatability analysis of point sources obtained from overlapping scans in 970418. Although the point-source extraction was done with PROPHOT PSFs from the protocamera, the positional and photometric repeatability was nevertheless excellent.