Subject: JEM-X Monday Meeting 2006-06-08

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

JEM-X status (SB): No hotspots. High hardware trigger rate just after
    instrument switch-on (duration: less than an hour) - are we not
    completely clear of radiation belt? We are no longer in the eclipse
    season. Could we have the DFEE turned on during the perigee passage
    to avoid some of the initial gain variation in a revolution also in
    the eclipse season?

OSA6 status (NL, NJW): j_src_properties is progressing. PIF values are
    generated on a per-event basis. First spectral extraction is close
    to being ready (count spectrum for source and background).
    The PIF is energy dependent at will be calculated for e.g. 10 energies
    and interpolate. The full solution for all sources simultaneously
    requires a lot of storage volume.
    (CAO): j_calib_gain_fitting has been delivered last week. Will be used
    quite soon. Starts work on j_cor_gain. j_cor_position will also be
    updated.

Hot spot handling in OSA 5 (SB): Revolution 348 is an example where the
    hotspot cleaning works fine. At very low signal the hotspot has a
    larger extension. Perhaps we should only use low energy events for
    hotspot determination. It is recommended to use events with STATUS
    value less than 256. Revolution 87 seems to be of the same kind.

    (CAO): How to handle the hotspot stripe in the y-direction in the
    shadowgram? This occurs at very low signals where the backplane
    position determination is overwhelmed by noise.

    Discussion of how to improve (if necessary at all) the j_cor_position
    with respect to hotspot detection. Be careful not to throw out
    a strong source seen through the mask perhaps far off axis.
    There is probably a way to avoid an a posteriori hot spot by setting
    the 'rowSelect' parameter for j_ima_shadowgram appropriately
    (to be verified).

Problems with our local 'pointing.dat' (SB): In revolution 348 there is
    an example where the on-target flag and the pointing identification
    change are out of synchronization.
    The pointing ID from the broadcast package is not always consistent
    with what the satellite really does. The OSA software handles this
    correctly, but our local IPF analysis packages may be wrong in some
    cases.

News from ISDC (NJW): Mostly discussion on j_src_properties and OSA6
    preparations and testing.

News from SPIE (CBJ): Science: Dark energy, WHIMP, determination of
    cosmological constants from X-ray observations.

AOB new dither patterns for coming key programs (NJW and all): Upper and
    lower limits for basic steps in pattern. For observation of a known
    single source staring is best. For detection of new (weak) sources
    a certain degree of dithering is useful to avoid artefacts disturbing
    the source recognition. An example: a hex pattern with 1 deg step
    could be advantageous. The upper limit would be the FOV limitation.

/NJW