Gain Notes for Revolution 1207

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.

NB: The last 3/4 of the revolution was strongly affected by some kind of gain suppression,
probably caused by solar activity. While the IC table has managed to correct for much of this
suppression, data afffected by it will show a strong gain variation over the entire plate
that cannot be corrected with the information available to us from calibration sources and
instrument background. Hence such time periods are always treated as BTIs of the
BAD_CONFIGURATION sort. These BTIs can be overruled by knowledgeable users, but anyone doing
so should be aware that both energy values and fluxes can be affected in indeterminate ways,
and this data cannot be used to make reliable spectra. Imaging, mosaicking and source finding
can still be performed with this data.
 

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 else. 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: 

The Xe line analysis performed using the IC table shows very poor gain
correction with all science windows having a Xe level 
within about +- 10% of the ideal. As usual however, it is recommended that users
avoid the first few science windows for energy-sensitive applications.


Calibration source number 4 (purple/orange) is no longer
used for calibration purposes since an anode strip directly under the source
has broken and no useable signal comes from this area of the detector any
longer.


JEM-X2: 

The Xe line analysis performed using the IC table shows okay gain
correction for most of the revolution, with all science windows having a Xe level 
within about 4% of the ideal. However between IJD 4627.5 and 4628.5 strong
variations in countrate cause a great deal of rapid gain variation in addition
to the gain suppression seen from IJD 4627.5 onward. Like the rest of the BTI
period, these SCWs should not be used for energy-sensitive applications.
As usual however, it is recommended that users
avoid the first few science windows for energy-sensitive applications.

CAO 07/09/2012