Subject: JEMX Monday Meeting 2005-08-29

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

JEM-X status (CBJ): IPF files show little hot spot activity, but the
      level has decreased considerably. JMX1 has been operated nominally
      since the period of high particle background.

SVR-5.0 (NJW): There are some issues to resolve vis-à-vis the spectral
      extraction in revolutions 39-44. In some cases the gain history
      could be improved and for some there are strange off-axis
      behavior (in JMX1 revol. 42 there could be a numerical error in the
      ARF). SB: perhaps the role of deadtime (incl. grey filter) should
      be investigated in more detail. It was decided to spend some more
      time to understand what is going on for the purpose of making better
      spectral extraction.

j_cor_gain (CAO): Suggestino that the fitting parameters could be put
      in the gain history table headers. This would minimize the impact
      on the data structure.
      An alternative suggestion: A new table should be attached to the
      original gain history table in basically the same format but with
      table rows with time intervals suitable for linear interpolation.
      This would serve the purposes:
        - could be handmade for particularly difficult revolutions and
          known HV changes could be incorporated at exact times
        - since linear interpolation does not involve fitting the result
          would be unique i.e. not depending on a particular fitting method.
      
      The requirement on ISDC would be to rerun the correction step for
      the archive and update all gain history tables - some taylor made.
      To begin with this action is only needed for particularly troublesome
      revolutions.
      
      The requirement on CAO would be to make a version of j_cor_gain
      that looks for this new extension and performs a linear interpolation
      if it is found. Otherwise the extension should be created (?).
      
Xe-line position (CAO): New curves for the line position have been made.
      Both for JMX1 and JMX2 there is an increase in position in the
      about 100 days in continuous operation whereafter the increase levels
      off (Epoch 5 for JMX2 and Epoch 8 for JMX1). Do we need more IMOD
      periods ?
      
      A plot of the detector spectrum showing the Xe and Mo lines
      is a good sanity check of the accuracy of the energy correction.
      It ought to be done by ISDC on a regular (perhaps for every 10 ScWs)
      as a supplement of the QLA or status monitoring.
      
Source positions in j_ima_iros (NL): The parameters for j_ima_iros have been
      changed with the new delivery of IMOD (version 13). There is a
      definite improvement, but it is not quite good enough. Make a
      comparison with results from CBJ 'private' software.

SDAST meeting 22-23/9 2005 (NL): We should be prepared with notes on
        - spectral extraction (NL)
        - j_cor_gain proposal (CAO)
        - Xe-line position/width plots (CAO)
        - spectral analysis vs. ARF (NJW)
        - ... (?)
        
Crab calibration (SB): The effect of the low energy cut-off can be analyzed
      both for the Fe calibration sources in JMX1 but also with the Crab
      spectrum when the HV is lowered e.g. in 5 levels, spending 10 ks at each.
      If we don't get a higher TM allocation the Crab should propably be
      off axis by 2 deg to avoid the grey filter cutting in
      but in a fixed position during the exercise.
      An OMC flatfield can also be used in which case the calibration lines
      will give the expected data.

NOB

/NJW
       
       External participants in the meeting are: Peter Kretschmar, Stefan
       Larsson, Stéphane Paltani, and Andrii Neronov. Unfortunately
       Silvia Martinez has another meeting at that time. Tim Oosterbroek
       may attend the meeting but at least he will have some time to help
       with software and analysis testing.
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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