Gain Notes for Revolution 2617

N.B. This revolution is affected by the extremely low gain generally, and by the
	even lower gain in the first third of the revolution. 

This is one of the later revolutions in the mission where the calibration
sources have become so weak that for the best energy determination an
IC Gain History table is needed. These gain history tables are found
automatically by OSA, or can be downloaded from the DTU FTP site.
 
All offline gain/energy corrections (including the IC tables) are based on the
two Fe calibration sources in JEM-X1, for both units, then corrected iteratively
using the instrument background lines (Xe, backed up by Cu and Mo).

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 rating:   Acceptable (within  8\%\ of ideal, except for settling zone). 
	This is a very noisy for the first third of the revolution where the Xe line cannot be seen, and it is not
	possible to determine a good energy correction except in interpolation across the sparse periods.
	Generally, the gain determination is excellent, as usual, except for one outlier, as indicated by the
	integrated Xe line position and strength, though Cu and Mo lines are missing.  The extremely low
	gain during the first part of the revolution has clearly caused many low-energy science events to be 
	rejected by the low-level discriminator. . 

JEM-X2 rating: Also acceptable. Some very weak misfitted Xe lines also occur in
	the later part of the revolution, as a consequence of the very low gain and the effect of the
	low-level discriminator. All the comments for JEM-X1 apply to JEM-X2.

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

CAO 22/03/2023