Gain Notes for Revolution 2686

There is no science data from the JEM-X2 unit which was kept
		switched off for all the revolutions with TOO observations
		of Swift J1727.8-1613.
While the Xe line was suppressed for much of the TOO observation
		some SCWs showed a Xe line of variable strength which allowed
		the gain level to be set within a few percent accuracy. 
Solar activity has finally decreased and very little gain suppression was
		seen during this revolution, hence this revolution is the first
		for since the first TOO observations where most of the revolution
		is a GTI. The BTI covers the period where gain is less than
		20 chans/keV: 8657.4 to 8658.2 IJD. During this period
		low level events will be lost in the onboard low-level
		discriminator.


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 (within  4% of ideal for all
		fits giving a realistic width, except for settling zone)

JEM-X2: No science data for this revolution.

CAO 21/09/2023