Gain Notes for Revolution 2692

During the TOO observation of the LMXB Swift J1727.8-1613
	the calibration data becomes very noisy and is not 
	possible to verify the gain determination during the TOO
The instrument gain dips below 20 chans/keV during which low
	energy events will be lost in the low-level discriminator
	so this requires a BTI = 8674.1 to 8674.6 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 (within 4\%\ of ideal, except for 
	settling zone and the BTI.)

JEM-X2 rating: Very good (within  2--3\%\ of ideal, 
		except for settling zone and 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 07/10/2023