Gain Notes for Revolution 332

	
	
A very interesting revolution with a High Voltage pre-switch on three steps below
nominal (first two points in each data set) and a small unscheduled switch off
at the beginning of the revolution. Gain smoothing is fine and one might
assume that all data from this revolution should be useable. 

However, there is some very interesting behaviour on source 3 
(Fe) that is not reflected on the other sources. During the first half of the
revolution gain is suppressed on the this source by upto 20%, leading to
corrected energies that will be upto 5% too large, depending on the science
window. In the 12 SCWs of survey data that are available we see a Xe line at
30.15 keV, about 2% too high. This is not a catastrophic degradation of the
gain correction, but it isn't optimal. 

We still don't know what caused this problem, but take a look at  our full analysis
to see what possibilities we've ruled out.

This problem has been corrected in the latest release of OSA (6.0). A corrected
gain history table created offline has been delivered to ISDC as an IC file, and
the OSA scripts can track down these IC files if they exist for a particular
revolution (very few revolutions actually need this sort of intervention). The IC
files are used instead of the automatically generated gain history tables created
at ISDC. The Xe line position evolutionm characteristic histograms and Xe/Mo/Cu
lines, averaged over the available survey data (12 pointings), were produced 
using data corrected with the IC file. If you don't have OSA 6.0 installed, or
are lacking the IC files, use the quick fix described below - it's the same
IC file.

 QUICK FIX: Download the  corrected  gain history table. It is the gzipped gain history table
            in FITS format. This is the gain history IC file for this revolution
            with the unusually low source 3 region corrected
            corrected by an amount proportional to the excess width. 
            Unzip the file and put it in the directory from which you are doing your
            data analyses, say . When you run the JEM-X Science Analysis Pipeline 
            (GUI) you will have to edit the hidden input parameter
            `gainHist' thus:
            gainHist = "//JMX1_gainHistoryIC_rev0332_001.fits[JMX1-GAIN-OCL,1]"
            Using this table will bring the Xe line
            down to within the general scatter of detector line positions 
            throughout the mission. Similar improvement is seen for the Mo and
            Cu lines.
 
CAO 26/9/2006