From relder@space.mit.edu Mon Jan  6 09:00:26 1997
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Date: Mon, 06 Jan 97 09:00:08 EST
From: relder@space.mit.edu (Dick Elder)
To: kaf@space.mit.edu
Subject: Grating roll data and questions
Cc: mm@space.mit.edu, dd@space.mit.edu
Status: R

Kathy
The vibration test caused only two gratings to move more than 1 arc minute. 
   4C3 changed -2.2 arc minutes
   1D1 changed  1.7 arc minutes
I don't believe 1D1 is located in the region of interest.

Looking at it another way only three M gratings had roll errors greater than 1 
arc minute when the unit was shipped after the vibration test.
   1DD6  at -1.14
   3B1   at 1.04
   1D1   at 1.35

It doesn't seem that this data provides any clues to the cause of a 20 arc min 
change.

When we did the vibration test on the engineering model without gluing the 
gratings, the trend was for the gratings to rotate counterclockwise when viewed 
from the HRMA side facing the detector.  I believe this motion causes the H 
images to move closer to the LETG and the M to move further away.  Does this fit 
the 20 arc minute error?

Do the photons at the 20 arc minute error position appear in a tight grouping or 
are they scattered over a range of several arc minutes?  

If a grating rotated by 20 arc minutes there is a moderate probability that it 
is leaning on another and might cause it to move by a few arc minutes.  Do I 
remember correctly that there is another cluster with 6 arc minute error but on 
the other side from the 20?  

I heard that they changed the temperatures in the chamber to attempt to solve 
some of the actuator problems.  Do you know the max and minimum temperatures 
that were used?  

Dick