From: Stephane Paltani <Stephane.Paltani@obs.unige.ch>

Hi Everybody,

Although I have been branded as the Dark Knight at the last SDAST
meeting, I hope you'll still want to look at Crab light curves from
Jem-X. I attached the four count rates in the standard bands, i.e. 3-6,
6-10, 10-15 and 15-35 keV (I always sent you the second band only,
namely the 6-10 keV). Those in the upper energy bands look much better!
This run shows the 4 bands with the new gain correction from Carol Anne.
I have also fixed the Crab at the catalogue position.

Compared to the previous attempt, the 10-15 and 15-35 keV are enormously
improved, except for the very beginning of the mission (rev 39). The
6-10 keV shows smaller systematics by a factor 2. The 3-6 keV does not
show any significant improvement. We also clearly see the (known) effect
of the switching on of the instrument after perigee.

Here are the estimates of the systematics in the 4 bands before and
after the new gain correction, and with the Crab fixed. The table below
gives the bracket of the fluxes in the different bands, without
considering rev. 39 and aberrant flux measurements:

             old              new           new+fixed
3-6         20-60            21-63           22-68
6-10        35-48            36-47           36-47
10-15       23-30            23-27           22-25
15-35       18-25            16-19           16-18

The biggest improvement is due to the new gain correction tables, but it
has effect mostly at high energies. It sounds like a similar work needs
to be done (if possible) to improve the gain calibration at low
energies. The 3-6 keV band should probably never be used, and this
probably needs to be explained more clearly in the documentation (with
possibly a known issue). What would be your recommended low-energy
threshold? Another important improvement (not visible in the above
table) is that the fixing of the source coordinates eliminates the vast
majority of "catastrophic failures" where the flux is suddenly lower
than expectyed by a factor ~10 (and by "eliminating", I don't mean that
these measurements are discarded; they actually end up with the correct
fluxes!).

I would like to restate what I already said at the meeting, namely that
Jem-X is a very important part of the Integral mission, and it is
essential that you keep focussed on the maintenance and improvement of
the Jem-X software and calibrations.

Best regards,
Stephane