Gain Notes for Revolution 1646

NB: This revolution has an autonomous switch-off and reactivation right in the
middle of the revolution. Usually, this would lead to a BTI being declared around
the deactivation period, but with careful offline calibration, all the SCWs
in this revolution can be corrected to within 4-5% of ideal which is good given
the current energy resolution of the instruments. 
However, since the gain determination is on average somewhat
worse than usual, and users should be wary of over-intepreting changes in
energy or spectra seen during this revolution - these are almost certainly
instrumental effects and not interesting astrophysical behaviour.

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.
See notes in revolutions prior to revolution 1433 to find out how to do this
if you don't already know.

All offline gain/energy corrections (including the IC tables) are based on the
two Fe calibration sources in JEM-X1, for both units.

Latest OSA software (version 10 and higher) automatically cuts out the first
Science windows of data from each revolution to ensure that people do not use data
from the instrument-settling period. This process can be overruled, but only by
experienced users.
	
JEM-X1: 

The Xe line analysis performed using the IC table shows good, useable gain
correction with all science windows (taken 1 at a time) having a Xe level 
within about 4% of the ideal, except for the usual settling points at the
beginning of the revolution. 
As usual, it is recommended that users avoid the first few science 
windows for energy-sensitive applications (automatically removed by OSA 10.0).

JEM-X2: 

The Xe line analysis performed using the IC table shows useable gain
correction with all science windows (taken 1 at a time) having a Xe level 
within 4-5% of the ideal, except for those in the settling period. 
As usual however, it is recommended that users avoid the first few science 
windows for energy-sensitive applications (automatically removed by OSA 10.0).

The JEM-X2 corrections are based on the JEM-X1 Fe calibration sources, since
all the Cd sources are now to weak to use.

CAO 25/02/2016