IPAC 2MASS Science and Analysis Working Group Meeting #4 Minutes

IPAC 2MASS Science and Analysis Working Group Meeting #4 Minutes, 9/27/95

Attendees: T. Chester, R. Cutri, T. Evans, L. Fullmer, T. Jarrett, D. Kirkpatrick, B. Light, C. Lonsdale, M. Moshir, S. Terebey S. Wheelock

T. Chester and T. Jarrett: have been studying the possibility of tracking seeing within a scan using a much smaller number of stars than currently used by G. Kopan for the scan-averaged seeing estimator pfrac. For stars, the `shape' parameter of GALWORKS tracks seeing well on a scan-by-scan basis. The sigma on the shape, however, appears to increase with increasing seeing (contrary to Tom's expectation that it ought to decrease with increasing seeing) and to also correlate with the seeing. Some scans were found to have anomalously high sigmas, indicating a possible problem with very bad seeing blowing up somewhere throughout the scan. This raised the concern that we would be able to identify scans with poor seeing but not to track seeing well throughout such scans.
Tom then plotted shape within a scan, using a six-star average to compute this seeing estimate. He found that in the previously identified anomalous scans there were regions within the scan where shape and sigma went wild.
Subsequent to the meeting Tom discovered that the anomalous sigmas were due to contamination of his `star' sample by galaxies, and that with these galaxies removed the shape parameter appears to track the seeing quite well. We will therefore investigate using shape, determined prior to GALWORKS in the pipeline, as a means of inputting to PROPHOT a monitoring of the seeing, so that PSF can be revised within a scan, as necessary.
D. Kirkpatrick: reported on his search for astronomically interesting objects in the 92-94 database that he and C. Beichman have just finished cleaning up (see last week's minutes). Using the APM database, Davy searched for extremely red objects; those with R-K>=6. Out of 54 objects meeting this criterion (the search was restricted to sources having a confirmation in the APM database), 10 are likely to be real. Four are M giants, 3 previously known (and in SIMBAD), and the fourth so identified from its colors. An additional 4 are probably late-type dwarfs. One is the previously known Pleaides brown dwarf candidate, and another is T. Chester's double M6 star. Two are previously unknown. The final two objects are of unknown nature and are candidates for imaging and spectroscopy; unfortunately neither are accessible for a few months.
Davy is now turning his attention to objects in the R-K=3-4 range, with unusually red J-K or H-K color; such objects would be candidate red QSOs, by analogy to the colors of the PG QSOs.