Gain Notes for Revolution 1927

This is a Crab calibration revolution, and with the Crab sometimes very strong
in the FOV (i.e. on axis during a dithering), the Xe lines are quite swamped
by the strong source in several of the science windows. Hence it is no possible
to verify how good the gain determination is during these periods.

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: very good (Xe line position within 2-3% of ideal). Some short
	periods it is not possible to verify the energy calibration since the
	Xe line is swamped by the strong signal by the Crab.

JEM-X2 rating: very good (within 2-3% of ideal)

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 09/03/2018