From hermanm@eureka Sun Mar 23 20:49:39 1997
Received: from eureka.mit.edu by wiwaxia AA04932; Sun, 23 Mar 97 20:49:37 EST
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Date: Sun, 23 Mar 97 20:49:36 EST
From: Herman L. Marshall <hermanm@eureka>
To: bertb@sron.ruu.nl, crc@eureka, dd@eureka, dph@eureka, dsd@eureka,
        frits@astro.columbia.edu, jdrake@head-cfa.harvard.edu,
        jiahong@head-cfa.harvard.edu, juda@cfa.harvard.edu,
        kaastra@rulrol.LEIDENUNIV.NL, kaf@eureka, prp@mpe-garching.mpg.de,
        theog@sron.ruu.nl, wise@eureka
Subject: news from XRCF
Status: R

I haven't had much time to work on grating data analysis or to send reports
(for odd reasons best left to discussion over beer) but I thought I'd pass
along one note.  Peter derived some simple ratios from the HETG/HRC data when
the DCM was stepping through many energies last Friday.  He computed the
ratio of the total of the HEG and MEG 1st orders to the sum of the 0th
orders.  This was relatively easy to do on the 2nd floor using QL software.
The numbers are in a file I have placed on line at SAO and at MIT:
/eureka/h1/hermanm/ASC/phase2g (at MIT) and ~hermanm/phase2g (at SAO).
One file contains the observed data, observed_ratio.dat, and the
second contains the predicted ratio curve, based on data provided by Dan
for the expander software: meg_zero-one_ratio.dat.  Take a look at them.

I made two figures (in IDL) and the PS files are sitting in the same
directory.  The first just shows the two files compared to each other
on the same plot.  The data look pretty close to the predictions.
This figure is called megheg_ratio.ps.  The second gives the differences
between the ratio interpolated from the ratio prediction file and the
observed value, relative to the predicted value.  Thus, the second one
shows fractional deviations from the prediction.  There are apparent
20-25% systematic deviations at the high energy end, from 4-7 keV and
the deviation seems to have a linear trend from near zero at 2 keV.

The ratios are useful ones because instrumental effects are mostly
eliminated.  No separation of the HEG and MEG rings was needed, of
course.

More later,

Herman