Gain Notes for Revolution 1977

This is the revolution after revolution 1976 where JEM-X1 was switched off for
the entire revolution. For the current revolution, 1977, JEM-X1 was switched on, but
only after JEM-X2---several science windows later. Since the JEM-X2 energy calibration
is performed using JEM-X1 calibration data, JEM-X2 could not be calibrated during
these first few science windows. A Bad Time Interval (BTI) has been declared for the
instrument response during this period, from 6771.5 to 6772.15 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 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: Exemplary (within about 1% of ideal, except for one outlier)

JEM-X2 rating: Excellent (within 2% of ideal) except for the BTI that starts the
revolution, from 6771.5 to 6772.15 IJD. OSA software will automatically cut out
the BTI, unless you are an expert OSA user and  know how to override the automatic
BTI selection.

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 20/07/2018