Gain Notes for Revolution 2638


NOTE: For a long period in the middle of this revolution there is no
useable calibration data, and so this period has been declared a
JEM-X BTI due to indeterminate energy determination. This
period can be used for imaging, but not for spectral analyses. This
revolution  is part of the eclipse season during which there are large
temperature changes in the instrumnets, and the gain varies by more
than a factor of 3 during the revolution. Despite this the gain determination
is good to within about 5-6% of ideal outside of the BTI.
	
BTI period: 8530.3 to 8531.7 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:  Acceptable (Xe line positions within about 5-6% of ideal, outside the
		BTI period). 

EM-X2 rating: Also acceptable outside of 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 15/05/2023