Gain Notes for Revolution 2591

N.B. It is suggested that users treat spectral data from the period 8406.1 to 8406.5 IJD
	with caution due to a large unexplained drop in gain during this period.
	WHile most of this change in gain is corrected for, other changes in
	the instrument performance may have occurred and events will have been
	lost in the low level discriminator. 

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:  Good (Xe line positions within  3-4% of ideal, except for 
		settling zone and a large number of misfits for which widths are extrememly
		high or low.)

JEM-X2 rating:  Good (within  3--4% of ideal, except for 
		settling zone and all the misfits period 8406.1 to 8406.5 IJD)   

CAO 11/01/2023