Gain Notes for Revolution 2693

The revolution is strongly affected by the TOO observation of Swift J1727.8-1613
	During this observation the Xe line largely disappears and it is not possible
	to verify the goodness of the gain determination.
Therefore a BTI is declared for the period 8677.45 to 8678.35 IJD.
During BTI it is impossible to determined the
	goodness of the gain determination, though the few faintly discernible Xe lines
	suggest that it does not deviate significantly from the rest 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: Very good (Xe line positions within 2-3% of ideal, except for 
		settling zone and the BTI.)

JEM-X2 rating: Very excellent  (within 1-2% of ideal, except for 
		settling zone and 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 12/10/2023