Subject: JEM-X Monday Meeting 2006-02-14

Hello all,

Due to yet another disk crash we've had mail problems yesterday, so
I'm resending these minutes (sorry if you get them a second time):

Participants: SB, JC, CAO, NL, NJW

JEM-X status (SB): HV has been reduced by a single step at
     beginning of revolution 407. This is a 10 V step and is
     expected to give af 14% reduction of the gain.
     Perhaps this reduction should be repeated not too
     long from now.
     (JC): No further anode losses (there is a certain
     concern that the gain is so high at the moment.

ISDC consortium meeting (NL, NJW, CAO): We have to give a
     presentation on the software development. Some
     results from the Earth observation should also be
     presented.

SDAST meeting (NJW): Is the timing good enough? We should
     check out the possibilities for the month of May.

Earth observation (NL): Images from what looks like
     auroral emission can be extracted by proper
     transformations where the center of the Earth is
     placed in the image center and rescaling according the
     apparent Earth size. A version of these images has
     been brought in the ESA press release.
     Spectral analysis (SB,NJW): The analysis of AN about
     the Crab spectrum derived the same way as the DXB
     spectrum gives a too large photon index (by 0.2). If
     this is applied to the DXB spectrum then the photon
     index comes out around 1.5 which is the expected
     value.
     The collimator is not a truly black body for the
     incoming X radiation. Some of the radiation can be
     scattered from the surface and end up at an
     unexpected position in the detector where it is
     counted as background. The DXB will be overestimated
     due to this effect and we must check if this gives a
     spectral effect. The double triggers can also have an
     effect.

Crab calibration (NL): We have asked for Crab observations
     at 3 different HV-settings (10 ks each). This seems
     feasible (as replied by PK). The pointing should be
     unchanged between these observations.

Sco X-1 observations: Georg Weidenspointner has got a very
     long observation to look for 511 keV emission. Is
     there a problem vis-a-vis JEM-X ? The hardware
     trigger limit is set to 40000 cts/8s. If the option
     to change this has been implemented by ISOC it should
     probably be reset to 60000 for this observation.

Galactic bulge observations (JC): Some results and a weak
     burst.

/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