Gain Notes for Revolution 2672


Note: This revolution starts with extremely low gain, so the
	period during which gain is less than 20 chans/keV is declared a BTI
	since below this value, the low level discriminator will permanently
	remove the lowest energy events, and so spectra will have a chunk
	taken out of them at the lower end. These time periods can well be
	used for imaging, but not for light curves or spectral. 
	The BTI is from 8620.2 to 8621.2 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:  Rating for this revolution: Good   (within about 4\%\ of ideal, 
		except for settling zone and a couple of misfitted points with 
		unrealistic widths. However, all of the poorest points are
		within the BTI, for which spectral data is consider
		unreliable, so these points are not considered in the
		assessment of the GTI.)

JEM-X2 rating:  Good (same notes as for unit 1)

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 20/08/2023