Documentation > SXT Observation Notes > this page

Change in SXT Diffuser Image in 7 Months

Image name: Diffuser_941108.png (click image to enlarge)
Image size: 426.548 KB (1024x512)
Date submitted: 08-Nov-1994


The image on the left is a flattened (using SXT_DIFFUSER2.PRO) diffuser
image made from the following 2 diffuser images.

0  8-NOV-94  04:21:30  QT/H  Diffu/Open  Half Norm L   4     2.9  512x512
1  8-NOV-94  04:23:38  QT/H  Diffu/Open  Half Norm C   4     2.9  512x512

This images looks very much like the comparable image from 26-APR-94.

The image on the fight is a difference image of restored SXT diffuser
images from 8-Nov-94 and 26-Apr-94.  Over this interval the total diffuser
signal increased by 3.4% but dark frames have not been subtracted before
taking the difference so it is possible that some of this increase is dark
signal.  The dark signal for this exposure is about 1.5% of the total
signal so it is certain that most of the increase is real -- as is also
revealed in the SLS plots. 

Note the various "absorption" features corresponding to x-ray damage as
well as the light areas corresponding to possible annealing effects and the
large circular feature that probably corresponds to some detail in
illumination pattern of the UV flood light.

The regions of greatest increase in x-ray damage are the large diffuse
patch on the disk in the NW and the very compact feature on the NW limb.
The damage here has resulted in about a 1% effect in the diffuser signal.

By and large, this is an encouraging result and indicates that it
is probably OK to leave the Yohkoh pointing as is for the time being.

Loren W. Acton

To the YLA Guide front page with side-frame
To contact us: