Date: Thu, 9 Oct 1997 11:19:05 -0700 (PDT) From: firstname.lastname@example.org To: email@example.com Cc: firstname.lastname@example.org, email@example.com, firstname.lastname@example.org Subject: 2MASS WG Mtg #132 Minutes IPAC 2MASS Working Group Meeting #132 Minutes 10/07/97 Attendees: R. Beck, T. Chester, R. Cutri, T. Evans, J. Fowler, L. Fullmer, D. Kirkpatrick, G. Kopan, J. Mazzarella, H. McCallon, B. Wheaton, J. White AGENDA 1.) 14-Bit Tests 2.) Telescope and Camera Status 3.) Observatory Duty 4.) Automated Observatory-Log-Dependent Processing 5.) Optical-Catalog Associations DISCUSSION 1.) 14-Bit Tests A bug was found in the code that simulated 14-bit raw frame data. A loop limit had a typo that cause the column loop to run from 11 to 256 rather than 1 to 256. The effects were very subtle but were detected by G. Kopan in a difference image made from corresponding coadded images. The bug has been fixed, and the test will be rerun. One other change is that the two least significant bits will be forced to 10 instead of 00. 2.) Telescope and Camera Status R. Cutri reported that the telescope control errors reported in last week's minutes have been fixed, and a new pointing model has been installed. Current performance involves RMS pointing control errors of about 6 arcsec. Consideration of sources for new camera electronics now includes JPL as a possible manufacturer. The electronics for the southern camera have been having problems and need to be repaired or replaced. 3.) Observatory Duty A problem in staffing the northern observatory in the period from 28 October to around 4 November has been solved. B. Nelson, H. McCallon, and G. Kopan will donate their efforts to fill this gap. Observers are still needed for the Dec. 25-31 run. 4.) Automated Observatory-Log-Dependent Processing The "Observatory Log Review" for 971004n includes a special-processing request not to use evening flat sequences unless no flat sequences were taken in the morning. This request was honored by R. Beck by editing the "tls" file so that the evening flat sequences would not be detected by the DARKS program. But this was only the run for quality checking, i.e, only calibration scans were processed for the purpose of reporting possible problems to the observatory. G. Kopan pointed out that there was no automated way to guarantee that the same avoidance maneuver would be taken when the entire night's data come up for processing later. Some discussion of techniques to automate such things took place, but no satisfactory resolution was achieved, and R. Cutri accepted an action item to pursue this issue further. 5.) Optical-Catalog Associations Optical catalog associations are being made in the POSMAN module POSPTS, as discussed in last week's minutes, but discussion is still going on concerning what modifications need to be made to satisfy all the users of this information. In addition to reporting the radial separation between the 2MASS point source and the catalog object, along with the corresponding direction, some desire has been expressed for a likelihood ratio parameter that indicates the plausibility that the associated objects are in fact the same object. The proposed addition of the chi-square match parameter supplies some of this, but it was pointed out that this gives no information about local source density, hence no hint of the possibility of a random coincidence due to high source density. The likelihood ratio number was proposed as a way to show the reduced confidence in a match in a high density region compared to a match with the same chi-square parameter in a low density region. It was not clear whether its failure to distinguish between a tight match in a dense region and a so-so match in a sparse region ought to be of concern. Perhaps several new parameters need to be added, e.g., the chi-square parameter and some indication of local density. The galactic latitude is immediately obtainable from the celestial coordinates, of course. In any case, it is desired not to keep changing the software interfaces, since at least four subsystems are impacted each time this is done, so it is important to arrive at a viable decision soon. To this end, a splinter group was identified consisting of T. Chester, R. Cutri, T. Evans, J. Fowler, C. Lonsdale, and B. Wheaton to look further into the matter. A final decision within two weeks is the goal.