Gain Notes for Revolution 421
	
JEM-X1: An ordinary revolution with fine gain smoothing. All the data from
this revolution should be useable. A large glitch on source four (purple/orange)
and some nice clear smaller glitches on source 2 (yellow/pink) in no way
affect the science data.

JEM-X2: The unit was re-activated in preparation for the Crab calibration in
revolution 422, which accounts for the strong gain increase at the beginning
of the revolution. Otherwise, this is an ordinary revolution with fine gain
smoothing despite heavy grey filtering. The grey filtering accounts for the
relatively small number of points in the gain history table, but this does not
affect the smoothing from which the gain calibration is actually derived.
All science data from this revolutin should be useable. However, it would be
unwise to read too much into small changes in line positions and other energy
information during the stablization period at the beginning of the revolution.
As explained elsewhere, during the stabilization periods after long dormant
periods, the microstrip plate is aging rapidly (ion migration) in a way that
varies from one point to another and cannot be completely corrected for by the
software. The period of steepest gain and SPAG change at the beginning of the
revolution is now officially a Bad Time Period and will be disregarded by
ISDC software: IJD= 2275.50 to 2275.90.


CAO 10/11/2006