Subject: JEMX Monday Meeting 2005-09-09

Please, notice the date.

Present SB, JC, NL, CAO, NJW

JEM-X status (SB): Bad space-weather for the moment. 2005-09-07 an X17 event
       from the Sun made JMX1 go to SAFE mode. After some hours it was
       re-activated, but after a while switched off again due to too high
       particle background.
       
       The hotspot was active at end of 2005-09-07 and a secondary hot
       spot has appeared quite close to the 'old' one. The count rate
       average over 30 minutes goes up to 30 cts/s i.e. comparable to the
       background rate. Over longer timeperiods, however, the average
       is a good deal smaller.
       
       Diagnostic events taken at periods where the hotspot was active
       have been analyzed and the conclusion is that the risetime is
       not a good separator between hotspot events and normal X-ray events.
       
       The method to reject hotspot events will be reconsidered.
       
j_ima_iros position determination (NJW): Positions based on peak fitting
       in the sky image are generally better than the ones reported in
       SRCL-RES. There are systematic deviations as a function of the
       source position in the instrument FOV. The coordinate transformation
       and conversion between sky and detector will be checked for errors
       and precision level.
       
Gain mapping (CAO): Getting the Xe background peak correct requires
       additional IMOD epochs. There is accumulating evidence that
       high background does lower the gain a bit all over the detector
       e.g. revol 276.
       The SPAG table could evolve in the beginning of an orbit where
       the accumulated ageing repeats in a few hours.

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