Gain Notes for Revolution 1845

N.B This revolution had an autonomous instrument shut down and re-activation which left 
small part of gain history data at the end of the revolution that had to be corrected 
manually. However, with this intervention energy corrections for the revolution fall
within the usual acceptible bounds, except for a couple of science windows immediately
after the second switch on, during which time the instrument underwent its usual
settling accompanied by very large changes in the instrumental gain. Also the
sinusoidal gain shown in the figures for the last part of the revolution is not
the gain used to correct the science data (since this would produce large sinusoidal
deviations in the energy determination). Instead the gain for JEM-X1 has been
fixed at 22.4 chans/keV and 24.4 chans/keV for JEM-X2 in the post-gap part of
the revolution.

This is one of the later revolutions in the mission where the calibration
sources have become so weak that for the best energy determination and
IC Gain History table is needed.
 

To get optimal results with this revolution it is necessary to use the IC gain history.
See notes in revolutions prior to revolution 1433 to find out how to do this
if you don't already know.

All offline gain/energy corrections (including the IC tables) are based on the
two Fe calibration sources in JEM-X1, for both units.

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: Excellent (Xe positions within 2% of ideal throughout)

JEM-X2 Rating: Very good (within 2-3%, except for SCWs in the two settling periods)

The JEM-X2 corrections are based on the JEM-X1 Fe calibration sources, since
all the Cd sources are now to weak to use.

CAO 03/08/2017