Subject: JEMX Monday Meeting 2005-08-15

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

JEM-X status (CBJ): The hot spot in JMX1 is still active on and off.
    Data outside the hot spot region is of usual quality. QLA at ISDC
    is now capable of rejecting the hot spot events.

Coming SDAST meeting in Copenhagen: A date: 22-23 Sept. 2005 is suggested.

Drift of Xe line and gain correction issues (CAO): An investigation is
    going on to verify that the Xe peak is correctly placed in the back-
    ground spectrum. Revolutions with problems in the gain fitting are
    identified and improved gain history tables are produced.
    
    The keywords PKCHAN_1, .., PKCHAN_4 are not changed but XE_CHAN is
    adjusted. OSA5 software is used for this investigation.
    
    The gain correction is the first step to get the source energy spectra
    right and in particular for the Crab calibration revolutions to be
    used for ARF production
    
    CBJ presented spectra from low-gain regions and high-gain regions that
    emphasize the need for individual ARFs for individual sources. Also the
    variation across the detector modulo the distance between electrodes
    was investigated and an effect demonstrated: More low energy counts
    appear just above the electrodes than in the region in between.
    Surprisingly enough this is also seen for the backplane electrodes.
    
New gain mapping (SB in absentia): New spatial gain correction maps have
    been constructed by finding the Xe peak position in a 32x32 rebinned
    map over several revolutions to obtain a sufficient number of counts.
    For JMX1 revols ~310 have been used, for JMX1 ~150
    A positive effect on narrowing the Mo and Xe lines has been shown
    also through OSA5 by defining new JMXi-SPAG-MOD tables.
    
    JMX1: Use old gain correction for revols <= 244 and new ones for
          revols >= 245 (dividing between IMOD period 8/9)
    JMX2: Use old gain correction for revols <= 93 and new ones for
          revols >= 94 (dividing between IMOD period 5/6)
          
New ARFs (NJW): When the gain corrections are as good as can be done in a
    few days these will be produced starting with revol. 300, 239, 170
    JMX1 and then revol. 170, 102, 45, 44 for JMX2

Better positions from j_ima_iros (NL): A refinement of some of the
    parameters (keywords) in JMXi-IROS-MOD has improved the source
    position accuracy - at least for the Crab. An investigation for many
    sources is under way. This means that a redelivery of j_ima_iros is
    not necessary for this purpose. The planned update of IMOD-GRP is
    sufficient.
    
JEM-X representative at ISDC (JC): NL will probably go there soon.

NOB

/NJW
    
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Niels J. Westergaard
Danish National Space Center
Juliane Maries Vej 30, DK 2100 Copenhagen O
Phone: +45 35325705; FAX:  +45 35362475