From email@example.comTue Mar 25 09:37:40 1997 Date: Thu, 30 Jan 1997 13:06:35 -0800 From: firstname.lastname@example.org To: email@example.com Cc: firstname.lastname@example.org, email@example.com, firstname.lastname@example.org Subject: WG Mtg #113 Minutes IPAC 2MASS Working Group Meeting #113 Minutes 1/28/97 Attendees: R. Beck, T. Chester, R. Cutri, T. Evans, J. Fowler, L. Fullmer, T. Jarrett, G. Kopan, B. Light, H. McCallon, S. Wheelock, J. White AGENDA 1.) 2MAPPS 1.0 2.) Camera & Telescope Status 3.) Association Parameters 4.) Tycho Proper Motions DISCUSSION 1.) 2MAPPS 1.0 R. Cutri reported that the date for delivery of 2MAPPS 1.0 is 5 February (not 3 February, since normal deliveries are on Wednesday). The purposes of this version of 2MAPPS are: (a.) to provide quick turnaround of processing of three-channel data; (b.) to check runtimes; (c.) to develop quality assessment capability. A poll of the subsystems was taken to determine significant liens expected in this delivery of the system. This is summarized below, where the minor tweaks needed by all subsystems are omitted. POSMAN: the position uncertainty model is unfinished; catalog associations (other than those involving astrometric catalogs) are not yet implemented; a problem with Tycho proper motions is unresolved (see item 4); a problem with high-density regions has just been discovered and has not been solved [note: this has since been determined to be a failure of the unix system sort routine; the file to be sorted was too large for the available workspace; PFPREP will be modified to do this sort internally]. PROPHOT: the full set of PSFs has not yet been generated (this will require a substantial amount of work with real three-channel data). BANDMERGE: statistical processing has not yet been implemented (this may possibly be done by delivery time). QUALITY: not quite all CONMAN functions have been implemented; most other QUALITY functions are in a very preliminary stage, as are most of the input files generated by other subsystems. DBMAN: just starting development. MPCAT: coding not yet begun. R. Cutri requested all cognizant engineers to send him a lien list via email by the Friday after delivery, February 7. 2.) Camera & Telescope Status R. Cutri reported that the camera is scheduled to be shipped to Tucson in early February, and the telescope is expected to be online in mid February. There will be a telescope shakeout period of unknown duration, but we should expect the first real three-channel data as early as late February. 3.) Association Parameters T. Evans reported that the catalog association parameter in the SIS POS05 is inadequate. The association field is too small, and other parameters are needed, such as the probability of the association being correct. She will propose specific changes to the SIS when she has determined exactly what changes are needed. 4.) Tycho Proper Motions H. McCallon reported that when proper motion was included in Tycho positions used for pointing reconstruction, the excellent results reported last week were degraded, especially in RA. Since the Tycho position epoch is close to that of the protocam observations of M67 (i.e., about 4 years difference), neglecting proper motion had little effect on the quality of the solution for the test scan; the residual standard deviation was 0.08 and 0.10 arcsec in RA and Dec, respectively. Including the proper motion should have made a very small improvement, but instead the residual standard deviations degraded to 0.43 and 0.15 arcsec in RA and Dec, respectively. Considerable effort has been expended on reexamining the implementation of the proper motion corrections, and no errors have been found. To investigate further, 2020 entries in the sample Tycho data set were position-matched with entries in the PPM catalog, and comparisons of the proper motions were made. Although the difference in epochs is about 60 years, the proper motions themselves were not expected to have changed very much in most cases. Scatter plots of the proper motions in RA and Dec were generated, along with correlation coefficients. The largest few percent of the proper motions correlated relatively well, but the smaller ones matched rather poorly, with an overall correlation coefficient of about 0.5 on both axes. The fact that the largest proper motions matched well would seem to argue against a problem with the implementation. The time baseline for Tycho proper motions was rather small (about a year in orbit), so perhaps the motion of the slower moving stars is not well determined (but by the same token, should not matter very much). An indication of this is the fact that some entries have relatively large uncertainties, with a mean uncertainty (per year) more than six times as great as for the PPM. It is possible that the sample catalog has some preliminary values which will be corrected when the full catalog is available. Some discussion with the catalog authors will be pursued to see what course to follow.