Date: Thu, 3 Sep 1998 15:49:32 -0700 (PDT) To: 2mass Subject: IPAC 2MASS WG Meeting #163 Minutes Cc: chas, stiening, bgreen Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-MD5: L/tHeHkMF8DJ9FOl+8vwUA== IPAC 2MASS Working Group Meeting #163 Minutes 9/1/98 Attendees: R. Cutri, S. Van Dyk, R. Beck, T. Evans, R. Hurt, J. White, J. Fowler, G. Kopan, H. McCallon, S. Wheelock, R. Tam, D. Kirkpatrick, D. Engler, T. Jarrett AGENDA 1.) Project Update -- Southern OPS Processing to Get Underway 2.) Last Week's Action Items 3.) 2MASS Sampler 4.) S. Schneider Visiting DISCUSSION 1.) Project Update -- Southern OPS Processing to Get Underway Northern OPS at Mt Hopkins should resume next week. R. Stiening will arrive there on Sept 8, with a restart of the telescope on Sept 9 or 10. Attempts will be made to improve the image quality. IPAC 2MASS volunteers will be needed to provide the analysis of the test imaging. Full OPS should resume thereafter. Pipeline modifications (e.g., PSFs) will be necessary. The dome is fixed at the southern facility. The southern pipeline should begin operations this Friday. W. Wheaton is within several days of having all production PSFs ready for the southern system. Preliminary cross-scan photometric bias corrections will be derived and applied using code written by G. Kopan and S. Wheelock. J. Fowler inquired about GETCAN for southern OPS. Before the main DARKS program runs, GETCAN is executed. It gets the obs date on the command line, and with that information, it searches through the darkhist directory for the most recent (relative to the obs date) five sets of acceptable responsivity images. The search is limited to the "hardware period" containing the obs date, since we cannot use hardware models in other periods of time during which the hardware behaved differently (e.g., prior to a dewar thermal cycle). There's a file in the darkhist directory named maskdat that contains a list of hardware-period subdirectory names and the obs dates bracketing the period; GETCAN reads that file to find out what period the current obs date is in. The information it gathers is passed to DARKS, where it is used to get the right canonical masks, darks, and responses. Since GETCAN knows how to find hardware-period-dependent data, it was suggested that it could be adapted to perform the same role for PROPHOT which may need to get different selections of production PSFs after hardware modifications, such as recollimation. R. Beck is running the first batch of darks to get the canonicals. R. Cutri decreed, no deliveries before starting southern OPS. 2.) Last Week's Action Items T. Evans was quantifying the scope of the MAPCOR error. She and R. Tam have been working mainly with the MAPCOR individual-band (not bandmerged) output. R. Tam ran CATCOR to match all sources in the old and new runs of 971116n within 2 arcsec. T. Evans then looked at all of the non-matched sources and found that all of them were either faint (m > 16) or were diffraction-spike sources, so the old and new runs matched up very well. They found that all of the changes in purge flags between the runs are as follows: 1) 53 H sources and 75 K_s sources are "new glints", i.e., marked as glints in the new run, but not the old. These are the sources that were incorrectly not marked because of the namelist problem. R. Tam found that only 3 of these H and K_s sources belong to the same bandmerged source. The results exactly follow what is expected from the incorrect parameters. 2) 19 H sources and 1 K_s source are "new not-glints" -- marked as glints in the old run, but not the new. These are the sourcs that were incorrectly marked because of the namelist problem -- the reverse of 1) above. These results also exactly follow what is expected from the incorrect parameters, and do not indicate any problems in the reliability of the correct parameters. 3) All other purge flag differences between the old and new runs -- 2 J sources, 17 H sources, and 1 K_s source -- are all attributable to a) changes in mag making a source toggle between diffraction flag = 5 and 6; b) the mess inside bright stars, causing small changes in extraction parameters; or, c) in the case of 13 H sources in scan 102, being artifacts of a bright source that is badly saturated in R1 and not extracted properly in any band (except, perhaps K_s; thus, its artifacts are not properly marked in either the old or new runs). More information will be provided in a webpage to be constructed by T. Evans. R. Cutri is maintaining a webpage listing all known anomalies, for which good bookkeeping is necessary. Another action item from last week was the "homework assignment" to test CatScan and the Survey Visualizer. J. Fowler's critique of the interface was directed at its complexity. H. McCallon commented that legends are needed on the Visualizer. B. Nelson commented on the problem of dynamic range in the Visualizer. T. Jarrett has suggested a sigma stretch to improve the display. Those who have not tried it were directed to do so. The homework has been extended one more week. R. Cutri was not pleased with the delinquents. Finally, G. Kopan and S. Wheelock provided an update on what could be called DMAGCOR, the routines to correct for the crossscan photometric bias. The preliminary version of DMAGCOR has been delivered. This program computes the psf-aperture photometric offset vs. cross-scan position. The program bins vs. cross-scan the magnitude offsets for all sources between 9 and 14.5, 8.5 and 14.0, and 8 and 13.5 mags for J, H, & K_s, respectively, which are not confused or artifacts. The mid-average is computed for each bin, as well as the estimated error and the number of counts. In the initial version, all calibration and survey scan blocks are processed as units, to increase the source counts per bin. Initial results for 980328s show four calibration blocks with many bins having less than 20 counts, and corresponding errors of 0.03 mags or more in the estimated offsets. Several features in the plots of corrections vs. time are not well understood at this time. The offsets should be well-determined for survey scans, but high-galactic latitude calibration scans are at risk, due to low source densities. How to diagnose and correct poorly determined magnitude offsets is an unsolved problem at this point in time. R. Cutri would like to run more southern nights with this correction to amass statistics, and then reexamine the problem. S. Wheelock has not yet checked output results from the calibration correction routine; the results need a spot check. The routine runs prior to CALMON in the pipeline, correcting the .bfpts file. R. Cutri would not be surprised if the "reset" button does not need to be hit. The extreme scenario might be to run the calibration using only aperture photometry as input. R. Cutri asked S. Wheelock to expect to have to test this. H. McCallon is about to update the positional uncertainties in the .cal files for the Sampler night. He will create new ".calo" files. The impact will be to have to reload the night into the database. Corrections of this sort for other nights will need to be applied to the database, which will involve consultation with the archive folks. Or, a night will have to be reloaded, with correction then applied to the night, and the night reloaded into the database. R. Cutri asked H. McCallon to draft an implementation plan for deriving and applying position error corrections using the working databases by the first WG meeting in October. 3.) 2MASS Sampler R. Cutri reported that, from a telecon with UMass the other day, a suggestion was made by T. Chester to NOT remove duplicate sources in the scan overlap regions as part of the 2MASS Sampler data sets. The schedule is to make the Sampler stable by Sept 7, let it ferment in the barrel for a month, with an intended new release date of Oct 7. 4.) S. Schneider Visiting T. Jarrett announced that S. Schneider is visiting IPAC from UMass to work with T. Jarrett on the "Great Attractor" scans. There is a Coma-sized cluster in the direction of the Great Attractor. 2MASS will provide enormous insight into the nature of the Great Attractor.