Date: Wed, 29 Jul 1998 12:00:16 -0700 (PDT) To: 2mass Subject: IPAC 2MASS WG Mtg #158 Minutes Cc: chas, stiening, bgreen Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-MD5: KXTpdTzlrCXoKlAV9K50Aw== IPAC 2MASS Working Group Meeting #158 Minutes 7/28/98 Attendees: R. Cutri, S. Van Dyk, L. Fullmer, R. Beck, B. Nelson, D. Engler, S. Wheelock, R. Hurt, T. Jarrett, J. Fowler, J. White, J. Gizis AGENDA 1.) R. Hurt joins 2MASS 2.) New news, old news 3.) 2MAPPS 2.1 redux 4.) 2MASS closes in on the Galactic Center 5.) 2MASS at IAU Symposium 190 6.) New red QSOs and L-dwarf objects 7.) The N-th coming of Gizis DISCUSSION 1.) R. Hurt joins 2MASS R. Hurt has officially joined the 2MASS team. His duties will include QA and continuing to adapt M. Brundage's software for the 2MASS QA website. 2.) New news, old news The northern facility is now in summer shutdown, due to the monsoonal weather in southern Arizona. R. Beck will be processing northern OPS data for 1998 on elvis, to take advantage of this lull in the action and catch up. R. Steining will go to CTIO to replace the southern electronics. The new electronics will be swapped in for the old, and test data will be taken. After data acquisition, the old electronics will be swapped back in. These data will be processed and analyzed at IPAC. Some changes are anticipated, e.g., in the southern darks, as a result. The stripe artifact may improve with the new electronics. The stripe artifact is an electronic echo resulting from a bright star on an image, with lots of counts over a small area of the array. This artifact also occurs for the northern data. The stripe artifact flag is now functional in MAPCOR. (J. Fowler wittily remarked that this should really be known as the "stars&stripes" flag.) R. Cutri emphasized that he will need bodies and eyes on these test data. R. Cutri thought that the Science Team meeting had been quite successful. Congrats all around to all IPAC 2MASSers, especially those working on the pipeline. He felt that presentations made by individuals were quite good, and that excellence and accomplishment had been demonstrated at the meeting. However, a concern still exists for the scan overlap bias and other problems. He would like to be able to throw the switch soon on the southern pipeline. 3.) 2MAPPS 2.1 redux R. Cutri discussed the various bugs that still exist in 2MAPPS 2.1, includingthe position bias between scan overlaps, on which H. McCallon reported (see WG Mtg #156 Minutes). The problem has likely been fixed, with H. McCallon (not present) to confirm this. L. Fullmer will check on this. Another problem is the southern PSF. W. Wheaton produced a model average PSF and variance map. From chi^2 analysis, it is clear that the variance is being underestimated. The chi^2 distribution and dispersion in the photometry is unacceptably large and divergent. Employing a single PSF and variance map seems to work better. This remains an outstanding problem. S. Wheelock was uncertain whether the 980403s RTB night had been calibrated. S. Wheelock and L. Fullmer will use T. Evans' procedure to extract MAPCOR lookup table information from the latest run using the new southern PSFs. R. Cutri discussed at length the photometric scan-to-scan bias, which is as much as 4 to 6 percent. Is this a flatfield residual? The answer is, most likely, "no". Thanks to G. Kopan, in part, it appears that it is due to the PSF being variable, both spatially and temporally. (This cause of the problem was smoked out by comparing the aperture and profile photometry.) This effect is intolerable in the south, where it can reach up to 9 percent, and thus does not meet Level 1 requirements. The problem is probably particularly bad for the south, due to the good seeing there. R. Cutri is seeking a solution to this problem. S. Van Dyk remarked about the variable PSF switch that exists in DAOPHOT. Clearly, this is not a possible solution. A lot of analysis is necessary to find an intelligent final solution. R. Cutri wants to either take the time now to make the proper correction, or start processing, develop the correction, and apply it retroactively to data already processed. R. Cutri encouraged one and all to look at the most recently-processed RTB nights as soon as possible. 4.) 2MASS closes in on the Galactic Center The nights 980702s and 980705s are currently processing on rex. These nights contain scans of the Galactic Center. These scans should serve as an excellent test of how good is the sky background estimator, versus far less dense regions of the sky. From the scans of Baade's Window (on 980319s) we already know that 3 to 5 percent of the stars returned magnitudes 99.999, especially in H. Source extraction records are already being shattered for the scans that have been processed so far. These scans should certainly make one heckuva nice gallery image mosaic. 5.) 2MASS at IAU Symposium 190 S. Van Dyk reported on his participation at IAU Symposium 190, "New Views of the Magellanic Clouds," held at the University of Victoria, BC, Canada, July 13-17. 2MASS had a poster paper on observations of the Large Magellanic Cloud (LMC). A bit shy of a 1 million sources have been extracted from those observations. The poster presented the color-color and color-magnitude diagrams derived from the extractions, showing many K and M giants, red and blue supergiants, AGB stars, carbon stars, and dust-enshrouded AGB stars, as well as foreground contamination. The ages of the giants are consistent with the current age estimates of the intermediate-age population in the LMC, about 2 to 5 Gyr. Many likely new carbon stars have been discovered throughout the LMC observed so far. These results are consistent with what the DENIS team is finding, which is quite satisfying, given the complementary nature of the bandpasses used for each survey. Both surveys have their strengths and weaknesses in identifying the red populations in the LMC. (This agreement is not trivial; S. Van Dyk, for instance, has been part of two VLBI collaborations which are observing the same object with the same telescopes, same bandpasses, and getting different results; here, two surveys are using different telescopes, different bandpasses, to observe the same object, and are getting very similar results.) The poster also put emphasis on the 2MASS Sampler this fall. S. Van Dyk made a large stack of 2MASS publicity fliers available to other participants at the poster. He was selected by the SOC to give a two-minute oral summary of the poster, where he made mention of the public nature of the data, the various 2MASS websites, and future data releases. 6.) New red QSOs and L-dwarf objects B. Nelson and D. Kirkpatrick, on a recent Palomar 5-m run, have found, from their color-selected (J-K > 2) sample of 35 candidate objects derived from 2MASS source extractions, 12 new AGNs and 1 possible L-dwarf. Visual inspection of raw spectra shows a mixture of other M and L dwarfs; 2 possible dwarfs could not be detected, and are presumably being observed at Keck. B. Nelson reports that about 60 percent of his candidate objects turn out to be QSOs or AGNs. The other 40 percent are double stars, M dwarfs, red galaxies with featureless spectra, the occasional carbon star, or, in fact, L-dwarf objects. 7.) The N-th coming of Gizis J. Gizis is again visiting IPAC and filling in for D. Kirkpatrick on QA. His only remark is that the QA webpage needs improvement. He has found what can be called the "K donut," on two different nights, 970724n and 970731n. A ring-like feature sporadically appears on K images only, and must be something that is out-of-focus in the K channel. It is about 20 to 30 coadded pixels in size. It may affect the K photometry. This artifact, of course, affects the quality of those nights. One last note made by R. Cutri and J. Fowler is that a lot more asteroids are coming through production lately, as these nights must be sampling more of the ecliptic. Soon, statistically significant color, brightness, and number distributions should be obtainable for these objects. ------------------ IPAC 2MASS Working Group Meeting #158 Minutes ERRATUM Note: the report from J. Gizis (Agenda Item 7) about the nature and quality of the QA webpage is inaccurate. Gizis' comment was regarding the 'SCAN' QA page, which needs improvement. The 'NIGHT'ly QA page, written by L. Fullmer, is working fine and is being improved and revised as recommendations arise.