Gain Notes for Revolution 2690

During the TOO observation of the LMXB Swift J1727.8-1613 
	there was a period during which no Xe line could be seen and the
	energy determination cannot be verified. Consequently there is
	a bad time interval (BTI) during 8669.35 to 8669.9 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: Good outside of the BTI, indeterminate during the BTI   
	(Xe line positions within about 4\%\ of ideal, except for settling zone)

JEM-X2: No science data for this revolution. 

CAO 05/10/2023