Gain Notes for Revolution 2696

Another revolution where the TOO observation of Swift J1727.8-1613
	at the end of the revolution. Since the Xe line used to verify
	the gain determination is swamped by the strong BHC signal at BTI has
	to be declared here to cover this observation.
 
The BTI is from 8685.45 to 8686.5 IJD
GainModel = 4 for this revolution, but the results show no
	direct gain dependence on countrate and the model contributes
	nothing to the gain smoothing. 

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: Very good (within  about 3% of ideal, except for settling zone)

JEM-X2 rating: Excellent (within 2% of ideal, except for settling zone,
		and one outlier)

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 20/10/2023