Gain Notes for Revolution 2758

This revolution contains a Crab observation,during which it was not possible
	to see the Xe instrument line that is used to verify the calibration
	process, consequently, during this period there is a BTI for Bad_Response
	during which it is not possible to determine the energy values of the 
	individual photons, or even the average gain of the detectors. 
During the BTI it is possible to use the data for lightcurves and images,
	but without spectral bands. And no spectra can be determined during
	the BTI. 
Even the all-revolution spectrum of the science data is so swamped by Crab
	photons that the Xe line cannot be seen, though individual SCWs after the
	Crab observation do show weak Xe lines. 
BTI: IJD= 8849.3 to 8850.7


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:  Acceptable outside the BTI (within  4-5% of ideal, 
		except for the BTI and several msifittted points with unrealistic widths.) 

JEM-X2 rating:  Outside of BTI Very Good (within 3--4\%\ of ideal, 
		except for the BTI and a few misfitted points with unrealistic widths.)

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 27/03/2024