Subject: JEM-X Monday Meeting 2005-09-19

Present: SB, JC, NL, CBJ, NJW

JEM-X status (SB): After 8 days of Safe Mode JMX1 was reactivated
       2005-09-16. Two days after Sco X-1 came into the FOV during a
       GCDE and the software trigger rate exceeding 25000 made the
       instrument go to Safe. It was reactivated after about 2 hours.
       For the rest of the revolution the limit to the software trigger
       rate will be set to 40000.
       [The future procedure to prevent these fall-outs due to known
        sources will be discussed during the upcoming SDAST meeting].

Detector spatial resolution (SB): In an attempt to assess the position
       resolution the diagnostic data from the beginnings of 50 revolutions
       were analyzed. When unfolding from the FRSS collimating size
       the results are
           FWHM ~ 0.8 mm  @ 22 keV
                  2.7 mm  @ 6 keV
       The latter number is a bit worse than given in the DPOS table
       of IMOD (which gives 2.1 mm). There is a question, however, on
       the precise construction of the Fe sources.
       CBJ and NJW will look into the Ferrara ground calibration results
       for a comparison.
       
Sensitivity vs. amplifier position (SB): The higher sensitivity of the
       detector close to the amplifier positions is demonstrated in the
       range 3-6 keV.

ARF production (NJW): Due to several disturbing results from the Crab
       spectral calibrations an investigation on the possibilities of
       determining the ARF from detector sensitivity studies from
       varying gain periods has been initiated.
       By using PI and PHA, RAWX and RAWY values from a set of counts
       the corresponding ARF can be constructed. What is lacking, however,
       is the efficiency of j_src_spectra to collect the source events.
       This can be estimated from the difference between Crab-on-axis
       and a blank field.

j_ima_iros source positions (NL): It is still not understood why the
       source fitting gives position errors that exhibit systematic
       features. Work goes on.

SDAST meeting (ALL): Probably no technical reports but presentations.

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