Date: Wed, 12 Aug 1998 14:00:14 -0700 (PDT) To: 2mass Subject: IPAC 2MASS WG Meeting #160 Minutes Cc: chas, stiening, bgreen Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Content-MD5: ZfT5gGAUnhhVvDRxz53LJg== IPAC 2MASS Working Group Meeting #160 Minutes 8/11/98 Attendees: R. Cutri, S. Van Dyk, L. Fullmer, R. Beck, T. Evans, R. Hurt, J. Fowler, G. Kopan, H. McCallon, J. White, S. Wheelock, R. Tam AGENDA 1.) R. Tam joins 2MASS 2.) 2MASS Mosaic of the Galactic Center 3.) Project News DISCUSSION 1.) R. Tam joins 2MASS R. Tam, who recently graduated with a BS from UCLA, joins the IPAC 2MASS team. (He is yet another Bruin to continue the siege on IPAC.) He will assist with data analysis toward final product generation. 2.) 2MASS Mosaic of the Galactic Center R. Cutri showed one and all an image that he had printed out, to test the eyes and astronomical knowledge of all team members. The image, of course, was a small mosaic of the region covering the Galactic Center. The source, Sagittarius A, is a bright near-IR source and clearly visible on the 2MASS composite JHKs image. A larger, more complete mosaic will be made and added to the Image Gallery. 3.) Project News The latest news is just a continuation of old news, with more problem shake-out for 2MAPPS 2.1. Northern observing should resume from the summer shutdown on or around September 1. A second northern telescope operator is being hired. When northern operations start again in September, R. Steining will work on the telescope collimation and polar axis alignment. The summer shutdown for northern ops will represent a new break between hardware periods. J. Fowler discussed separate "hardware periods," for which distinct data sets must be maintained, and the steps involved in adding new hardware periods. Each hemisphere has a "history" directory; histn is the directory for the north, and hists is the directory for the south. Each exists in a directory tree structure set up by OPS with pathnames that may change as needed for operational reasons. Each hemisphere's history directory contains a subdirectory named darkhist and a subdirectory named pfprep. These are used by the DARKS and POSMAN subsystems. Each of these contains subdirectories named a, b, c, .... The single-character-name subdirectories correspond to "hardware periods", i.e., intervals of time within which the observational hardware is modeled as discontinuously different from other intervals of time. Currently, there are two data items kept separate by hardware period: mask images and model parameters, used by the PFPREP module stored in NAMELIST files. In the darkhist directory underneath histn and hists, a file named maskdat associates the a, b, c, etc., directories with start and stop dates that define the hardware period for each directory. All that matters is that ranges of nights are segregated into subdirectories. In the south currently only one hardware period exists, so maskdat in hists/darkhist consists of only one subdirectory. OPS uses a program named getmask to automate retrieval of data that depend on the hardware period; this program reads the maskdat file, finds the period in which the night being processed falls, and echoes the one-character directory to stdout, from where it is used to access the corresponding data. When a new hardware period is defined, the following updates must be made: a) A new one-character directory must be made under darkhist and pfprep for the hemisphere involved; b) a new set of masks for the period must be placed in the darkhist subdirectory; c) a new nl.pfprep for the period must be placed in the pfprep subdirectory; and, d) the maskdat file in darkhist must be edited. R. Cutri asked R. Beck to work with J. Fowler on new subdirectory generation for mask images and NAMELIST changes, as well as for startup darks. R. Cutri stressed that more southern data needs processing, and therefore, processed data online needs to be moved off-disk to tape, to make disk space. The highest priority still is the PSFs for 2MAPPS 2.1 startup. Some progress on this front has been made. W. Wheaton had reported that the PSF ID numbers and lookup tables correspond to reality (see WG minutes #159). A breakthrough has occurred in the production of the southern PSFs, and the resulting chi^2 distributions look better (more like the north). R. Cutri asked T. Evans to populate the lookup tables, especially for poor seeing conditions in the south. G. Kopan gave an update on the magnitude-crossscan position bias problem. Some progress has been made, with analyses for two of the southern RTB nights. No obvious correlation has been found with telescope temperature. (In all tests the default aperture magnitude is selected.) The magnitude differential as a function of crossscan position appears to be, and will undoubtedly continue to be, a variable relation both from night-to-night and even scan-to-scan throughout a single night. L. Fullmer was asked to look at the statistics for the scan-to-scan overlap regions. The parameters at work for this problem need to be isolated. R. Cutri hopes to have correction software by the second week of September for the start of southern OPS processing. He would like at least a zeroth-order correction, to reduce the magnitude differential from about 9% to, maybe, 2 or 3%. The goal is to get the southern OPS going soon. R. Cutri and S. Wheelock discussed the J-band zeropoint drift, which is quite systematic and not unexpected. It comes about since the J-band used can be easily affected by water vapor, which effectively changes the bandpass. S. Wheelock has a prototype working for a constrained linear fit to the trend, which amounts to a 0.1 to 0.2 magnitude drift. (CALMON originally had a linear variable zeropoint, which was removed by suggestion of the Science Team before 2MAPPS OPS began.) The effect at H and Ks exists, but is small. The night 980112n has been tested with the prototype code. A retroactive application is necessary for, especially, the most severely-affected cases. Finally, a new Enterprise 450 ("Son of Barney") has been ordered, as well as a new 450 for the database effort (see "Christmas in August" from WG minutes #159).