Gain Notes for Revolution 894
	
JEM-X1: No scientific data or gain history for this unit.


JEM-X2: The last of the revolutions containing SCO X-1 observations. The
	automatically generated ISDC gain history table contains lots of
	dropped values that confuse the gain smoothing (see Cd lines labelled
	'ISDCgain'). Hence it is necessary to use an IC gain history table
	produced offline at DNSC. This is in production and will be
	available both through this page and from ISDC in a couple of days.

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. 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.

The Xe line analysis, using the IC table, confirms the very
good gain calibration for this revolution with all except the very first Science
Windows having a Xe line position within about 1% of the ideal value.
As always, however, it is suggested that
users avoid the first few science windows in each revolution since this is
where the instrument warms up and gain variations across the plate settle down.


CAO 24/02/2010