Gain Notes for Revolution 976

This is one of the later revolutions in the mission where the calibration
sources have become so weak that for the best energy determination and
IC Gain History table is needed.

To get optimal results with this revolution it is necessary to use the IC gain history
table that has been created offline at DNSC, instead of the gain history table
created automatically by OSA. If you have the newest package of IC files from ISDC
and these are correctly installed, OSA will find the IC gain history table automatically
and you don't need to do anything. The updated ISDC Instrument Characteristics
can be downloaded from
http://www.isdc.unige.ch/integral/download/osa_sw


However, if you don't have the IC gain table
package from ISDC you can download the table from the gain history archive by
anonymous ftp through the link provided. Download the table to some suitable
subdirectory for your analysis, then set the hidden OSA parameter gainHist:
gainHist="<my subdirectory>/<IC filename>". These files are used instead of the
automatically generated gain history tables wherever there has been an unusual or
non-linear behaviour of the detector gain.


	
JEM-X1:

 This was a warm-up revolution for JEM-X1, that is to say the unit had been
inactive for a long period of time when it was switched on for this revolution,
as part of the SPI annealing program. This means that both long-term ion charge
redistribution was happening within the microstip plate as well as the usual
surface charging, and larger-than-usual temperature increase. This all combines to
make the gain variation at the beginning of the revolution very large. Also, during
the ion redistribution, the spatial gain variations across the microstrip plate
change in just the way they did as the instrument aged with continual use, meaning
that the local gain on the plate is largely unknown until the plate is properly
warmed up, and reaches the SPAG corresponding to the one in the instrument model
table for this revolution. Due to all these effects, it is strongly recommended that
users avoid the first third of this revolution for all energy-sensitive
applications. 

The first part of the revolution has been declared a Bad Time Interval for this
instrument, and will be ignored by the OSA processing. The BTI is IJD = 3935.8 - 3936.4

The Xe line analysis performed using the IC table shows okay gain
correction for the last 2/3 of the revolution with science windows having a Xe level 
within 2-3% of the ideal.

JEM-X2:

The Xe line analysis performed using the IC table shows excellent gain
correction with all except the very first science window having a Xe level 
within 2% of the ideal.

CAO 26/10/2010