Date: Wed, 18 Feb 1998 12:41:28 -0800 (PST)
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To: 2mass
Subject: IPAC 2MASS WG Mtg #143 Minutes
Cc: chas,, stiening, bgreen
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Status: RO

           IPAC 2MASS Working Group Meeting #143 Minutes

Attendees: C. Beichman, R. Cutri, T. Evans, J. Fowler,
           L. Fullmer, T. Jarrett, G. Kopan, J. Mazzarella,
           H. McCallon, B. Nelson, B. Wheaton, S. Wheelock,
           J. White


1.) Southern Observatory Status
2.) 2MAPPS 2.0 Test Status


1.) Southern Observatory Status

    R. Cutri reported that the camera for the southern
observatory has been shipped to the mountain and is expected to
arrive next week. First light is expected during the first week
of March.

2.) 2MAPPS 2.0 Test Status

    The testing of 2MAPPS 2.0 has proceeded through the first two
nights of the RTB, 980114n and 971116n. Cognizant engineers are
requested to examine data products relevant to their subsystems
and make appropriate fixes and redeliveries. All tests are
running on barney in /b1/OPS. The previous run of 980114n is also
there, renamed 980114n_old, but much of this is scheduled to be
deleted very soon to free up disk space, and very little besides
quality files will be kept.
    A subsystem-by-system discussion took place, most of which
involved details of limited interest and thus not suitable for
wide dissemination. In general, quality indicators look good in
all areas, while some problems do exist and are being worked.
Some of the highlights were as follows.

     (A.) Two scans have anomalous cross-scan Tycho residuals in
     their final associations files after having had very small
     residuals in the intermediate position-reconstruction files
     (H. McCallon will investigate; after the meeting, he found
     that the two scans are of such low density that they may be
     flagged in QA review as not satisfying the Level 1 Req. for
     position reconstruction. Note that this does not imply the
     need to rescan these unless they fail some other aspect of
     the QA review).

     (B.) An apparent cross-scan responsivity dependence has been
     found in the overlap areas of adjacent scans, amounting to
     about 1% full-width variation, and using responsivities
     computed from more chronologically nearby twilight-flat
     sequences did not make the problem go away, but it reversed
     its sign. The effect of the new moving-window averaging of
     responsivities on this anomaly will be monitored. It may be
     due to simple estimation error in the technique used to
     compute responsivities from twilight flats, although it is
     not known why that should correlate with cross-scan position
     unless a brightness gradient in the twilight sky existed,
     which is possible.

     (C.) Distortion correction has been implemented in POSMAN
     but is currently turned off because downstream processors
     are not ready for it to be turned on. It has been decided
     that PICMAN will not need to make distortion corrections
     (subject to conflicting information from the southern
     observatory), and the changes needed to implement such
     corrections in PROPHOT appear to be manageable, but will not
     be included within 2MAPPS 2.0.