Gain Notes for Revolution 2821

Solar activity at the end of this revolution has made it hard to 
	find the Xe instrumental lines and caused a strong gain suppression
	so that the gain is less than 20 channels/keV during the last
	fraction of the revolution. When the gain is very low many low-energy
	photons are filtered out onboard by the low-energy discriminator.
	Consequently, from IJD 9018.3 and for the rest of the revolution, 
	the revolution is declared a Bad Time Interval due to poor instrument
	response. BTI = 9018.3 to 9019.5 IJD. 

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: Excellent (within 2\%\ of ideal, except for 
		settling zone, some misfitted points and the BTI.)

JEM-X2 rating:  Also excellent except for the BTI
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 22/09/2024