Subject: JEMX Monday Meeting 2004-10-04

Present: CAO, SB, ILR, NL, JC, CBJ, NJW

JEMX status: After onset of JMX2 it takes about 5 hours for gain
             stabilization. This has implications for the recent Crab
             calibrations where the first measurements are somewhat
             disturbed by this continuing gain increase.
             
             JC: The Xe line position in energy (measured by PI value)
             is slowly increasing with time. This probably means that
             the gain under the FRSS sources is decreasing. CAO will
             introduce a time dependent correction factor for the OSA5
             delivery of j_cor_gain.
             
             CBJ: The weighted average of Kalpha1(2) and Kalpha2(1)
             line position from table is 29.696 keV for Xe.
             
             JC will try to find the Mo line (at 17.4 keV) to see if
             its time dependence is similar to the Xe line, but this
             can be tricky and will take some time. The aim is to see
             if gas deterioration or local gain decrease is the cause.
             
             For the next Crab calibration we should change the cathode
             voltage (VC) with a factor 1.5 (about the limit). If the
             gas is OK there should be no change of Xe peak position
             
             JMX2 has not shown any degradation while dormant.
             
Crab calibration: The measured flux changes with position in the FOV
             which is a concern. A tilted collimator can explain some
             but not all of these variations. Work is continuing.
             
ISWT meeting: Dither pattern will be changed so that consequtive cycles
             will not be identical (roll angle change by +-3 deg)
             
             Unused TOO time of the core program will be used for ironing
             out the GPS coverage and saved for later (fifty-fifty).
             
Data analysis: Perseus and SGR1806 are analyzed.

/NJW
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Niels J. Westergaard
Danish Space Research Institute
Juliane Maries Vej 30, DK 2100 Copenhagen O
Phone: +45 35 32 57 05; FAX:  +45 35 36 24 75