Gain Notes for Revolution 1639

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 very good gain
correction with all science windows (taken 1 SCW at a time) having a Xe level 
within 2-3% of the ideal, only 3 points fall outside 2%, and only a handful of
real points fall outside 1% of ideal. All the settling points at the begining
of the revolution are not considered 'real' since they are measured during the
settling period when the instrument is warming up and spatial gain changes are
changing rapidly and unpredictably all over the plate. 
As usual, therefore, 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 excellent gain
correction with all science windows (taken 1 at a time) having a Xe level 
within 1-2% of the ideal, except for the settling points at the beginning of
the revolution. The majority of the points are actually well within 1% of ideal. 
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 04/02/2016