Gain Notes for Revolution 1739

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 excellent gain
correction with all science windows (taken 2 SCWs at a time) having a Xe level 
well within 2% of the ideal, except for a single settling point. The vast majority
of points are within 1% of ideal.
As usual, it is recommended that users avoid the first few science 
windows for energy-sensitive applications (automatically removed by OSA 10.0).

CAO 24/10/2016

JEM-X2: 

Overall revolution scores a 'Good' rating with all points that are not settling points, 
within 2-3% of ideal with only one outlier at just over 4% of ideal. Second half of 
revolution scores 'excellent' as usual. This is probably due to the very rapid
gain changes seen in the JEM-X1 instrument which may not map particularly well on
to the JEM-X2 instrument, which may lag or lead these changes, and hence produce
as very slight (1% or so) gain mismatch. This is a limitation of basing the
JEM-X2 calibration on the JEM-X1 calibration data that is bound to arise.
However, given the slight worsening of the determination of the centroids of
the instrument lines by 1-2%, compared to the overall energy resolution (about 20%)
this is a very small decrease in performance.

As usual, 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 to0 weak to use.

CAO 26/10/2016