From jwf@ipac.caltech.eduWed Sep 10 14:43:39 1997
Date: Wed, 30 Jul 1997 15:17:51 -0700 (PDT)
Subject: WG Mtg #128 Minutes

           IPAC 2MASS Working Group Meeting #128 Minutes

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


1.) ERB Meeting
2.) Read1 Solos
3.) Tunable Parameter Summaries
4.) Mt. Hopkins Experiences
5.) Tycho Distribution and Tile Coverage


1.) ERB Meeting

    R. Cutri reported on highlights of the Executive Review Board meeting. The
board was extremely pleased with the progress made since the last review, and
although the subject of the meeting was technically not the readiness of
2MAPPS to support the mission, this readiness was nevertheless observed to be
at an advanced state, with a review to be specifically scheduled after next
February, when delivery of the 2.0 version of 2MAPPS is to be made.
    The board judged the probability of meeting the Level 1 requirements to be
acceptably high and noted that these requirements cannot apply to interim-
release products, because some aspects of the Level 1 requirements cannot be
evaluated until after all data have been processed (e.g., photometric
uniformity). The board will recommend to NASA that the 2MASS data products be
included in the Astrophysics Data Program.
    Some concerns were expressed by the board, including: (a.) the science
team needs to be more involved interactively with IPAC in the 2MAPPS parameter
tuning activity; (b.) it is not clear whether sufficient margin in runtime
exists, especially considering the complete reprocessing of all data after the
data acquisition phase has ended; (c.) more spare chips should be on hand;
(d.) better planning of external quality assurance activities is needed. In
addition, the board warned against what it saw as a possibility that too much
effort might go into salvaging unacceptable data through extra software
    This last point generated discussion of the status of hardware and
software fixes for the J-band bias-fluctuation problem. It was pointed out
that significant design changes after implementation of a complicated software
system have traditionally been one of the most prolific sources of insidious
bugs, and that the possibility of hardware fixes should be exhausted before
seriously considering code modification. Beyond diagnostics and data
rejection, it is not even clear what software fixes would be possible, whereas
the nonexistence of the symptoms in the H and Ks bands (as well as the
protocamera) demonstrates the possibility of correctly functioning hardware.
    A complete formal report will be issued by the board in a few weeks.

2.) Read1 Solos

    T. Evans reported seeing a number of H-band Read1-only point sources in
the output products where the coadded images show nothing at all. These point
sources turned out to be one-out-of-one sources, implying that they originated
either from cosmic-ray hits or hot pixels such as those that have been seen in
the Ks band. The absence of any corresponding Read2-Read1 sources or objects
in the coadded images indicates excellent functioning of the deglitching code,
but further discussion revealed that the system has no filter for such one-
out-of-one point-source detections other than the sort of cleanup activity
scheduled for final-product preparation. Tracey and Roc accepted an action
item to investigate how such events are supposed to be handled in the 2MAPPS
design and to propose any needed modifications.

3.) Tunable Parameter Summaries

    R. Cutri requested all cognizant engineers to send him a list of tunable
parameters via email by Friday, August 8. After all such parameters are
identified, along with their current default values, priorities will be
assigned and plans for optimizing values will be finalized.

4.) Mt. Hopkins Experiences

    B. Nelson and H. McCallon reported on their experiences running the
northern-hemisphere telescope at Mt. Hopkins. Brant indicated that the level
of automation was impressive, but that more extensive documentation and
guidelines, as well as better lighting in the control room, would improve the
working conditions. The main problems were camera timeouts and formation of
ice plugs. Howard reported that setting-up and shutting-down activities could
be fairly hectic, but in between, the extensive automation did allow a
somewhat more leisurely approach to maintaining the observer's log and
watching out for camera timeouts, weather changes, and artifacts on the
monitor display of the data frames. Both agreed that some additional automated
input to the logs would be desirable.

5.) Tycho Distribution and Tile Coverage

    H. McCallon reported that he had set up tile-access routines for the full
Tycho catalog, which is now in IPAC's possession. In doing so, the
distribution of Tycho stars with respect to the tile geometry was investigated
and found to be essentially as expected. He will soon be delivering code that
examines achieved tile coverage and reports the results to the QUALITY