Gain Notes for Revolution 1684

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.

N.B:  : This revolution was severely disrupted by at lack of synchronization on the JEM-X2
high-speed line (HSL) that should carry the JEM-X2 science data to the processor. This
means that while HK data is unaffected for this unit (calibration data) the science
data is missing. So while we can correct very roughly for the average calibration of
the JEM-X2 unit, using what little science data there is to verify the energy
determination, we cannot vouch for the goodness of the individual science windows,
few of which will contain any science data. USERS ARE ADVISED TO BE VERY CAUTIONS OF
ANY ODD ENERGY VALUES IN THEIR DATA FOR THIS REVOLUTION, THEY ARE CERTAINLY AN
ARTIFACT OF THE DATA AND PROCESSING LIMITATIONS IN THIS REVOLUTION, AND NOT AN
INTERESTING SCIENTIFIC RESULT. JEM-X1 is not affected by this problem so comparisons
of the science results between the two units should indicate where JEM-X2 energy
determination is less than optimal.
 

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: 

The Xe line analysis performed using the IC table shows excellent gain
correction with all science windows (taken 1 at a time) having a Xe level 
within 1-2% of the ideal, except for the early settling points, two of which are useable
within 3% of ideal. The vast majority of the points are within 1% of ideal.
As usual, it is recommended that users avoid the first few science 
windows for energy-sensitive applications (automatically removed by OSA 10.0).

JEM-X2: 

The Xe line analysis performed using the IC table shows useable average gain
correction with any science windows that contain science data. The average
position of the rather weak Xe line being 26.55 keV which is exceellent, but
tells us nothing about individual science windows, which could easily be 4 or 5%
from the ideal energy correction. 
As usual, it is recommended that users avoid the first few science 
windows for energy-sensitive applications (automatically removed by OSA 10.0).

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 02/06/2016