IPAC 2MASS Working Group Meeting #81 Minutes

IPAC 2MASS Working Group Meeting #81 Minutes, 12/05/95

Attendees: R. Beck, T. Chester, R. Cutri, T. Evans, J. Fowler, L. Fullmer, D. Kirkpatrick, G. Kopan, B. Light, H. McCallon, J. White


  1. Astronomical Catalog Access Methods
  2. Status Reports


  1. Astronomical Catalog Access Methods -- R. Cutri recommended that system-level consideration be given to methods of accessing astronomical catalog records as functions of scan location. Since a large part of the 2MAPPS processing will involve accessing catalogs for information on sources lying in or near a scan, efficient methods for doing so will be needed, and it is desirable to limit the proliferation of independent schemes in order to reduce duplicated effort and incompatible techniques. The same concern applies to any sort of data access involving mapping from celestial positions. This sort of mapping problem has been solved before in past projects, so starting from scratch would constitute reinventing the wheel, although some specialization to specific applications will clearly be needed, and applications involving off-the-shelf DBMS software will probably just use what is already built into the package (although this has been found in certain circumstances to be very inefficient).

    With the emerging standard strip geometry describing the scans to be executed to carry out the survey, it is clear that celestial mappings will probably profit from use of the strip ID numbers as direct-access record numbers within which to read pointers to the desired data records or the records themselves. A variation of this is to use the strip ID as part of a filename template for opening a file containing information pertaining to the strip. Mappings from celestial coordinates to strip IDs and from the latter to the strip coordinates (e.g., center point, four corners, etc.) can be developed easily from the IRAS methods.

    The point at this time is for developers needing these capabilities to be aware of the others with similar needs, to share development effort, and to take advantage of existing methods.

  2. Status Reports --

    R. Cutri: Final calibration of the 95 data is currently running; analysis of the M67 data has revealed several very red objects which apparently are galaxies whose emission lines reveal redshifts of about 0.16 (the redshifts were obtained by J. Huchra).

    G. Kopan: FREXAS version 1.0 is almost ready to go into testing.

    T. Chester: Will give a presentation describing 2MASS to the Users Committee on Wednesday, December 6.

    D. Kirkpatrick: Followup Palomar runs and analysis of several very red objects have been carried out; objects include M5-M7 dwarfs and an M7-8 giant.

    B. Light: Has been studying the behavior of Read1 positions relative to Read2-Read1 positions; the discrepancies vary from scan to scan, especially between forward and backward scans; variation within a scan has not yet been studied; a memo will be issued describing the results obtained from the analysis.

    J. White: Has been coding RdFrame and negotiating small adjustments to the Obervatory/IPAC interface Document.

    R. Beck: Has started working on EXEC.

    L. Fullmer: has made an RGB image from coadds from Coma Cluster scans; the technique should be applicable to 2MAPPS, although registration problems had to be overcome that should not arise in 2MAPPS.

    T. Evans: Has spent most of the time lately on IRTS, but is starting work to remove liens in the MAPCOR design involving the use of the PSF as a function of seeing.

    H. McCallon: The 2-peg PosRec program has been tested with some cases requested by J. Carpenter and R. Cutri; the former tests ran well, but the latter cases presented some tougher problems which are nevertheless expected to be overcome.

    J. Fowler: issued version 1.4 of the FDD (incorporating precision requirements) and has started writing the BandMerge SDS.