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SXT Straylight Situation -- Phase 3

Image name: Straylight_phase3_SFT.png (click image to enlarge)
Image size: 533.819 KB (1024x986)
Date submitted: 02-Sep-1996

							9/02/96, Rev. B
							L. Acton

                   SXT STRAYLIGHT SITUATION -- Phase 3 

A.  Thin Aluminum

This image illustrates the relatively small change in the Al.1 straylight
pattern caused by the 3rd SXT entrance filter failure which took place on or
about 25-Aug-96.  After selection the two top images were 

	1.  Dark_subtracted with DARK_SUB.
	2.  De-spiked with img=de_spiker(img0,10).
	3.  Flattened with flat=img-big_smooth(img,10).
	4.  Displayed with tvscl,flat>(-10)<10.

Ignoring the blem the before (LH) and after (RH) flattened images are quite

The lower LH image is the after-before difference of the flattened images and
shows only a little sharpening of the NE and SW limbs and some change in the
network pattern.  The lower RH image is the before-after difference of the
two terminator images themselves.

Although the increase in the SLS signal level was about 40% as I reported
earlier, the increase in the Al.1 image straylight is more like 20%.  This
value is still uncertain because of uncertainty in pointing due to some
problem with current ATT files. 

It appears that the Al.1 grill pattern is unchanged by the new leak.  More
work needs to be done on the network pattern when all of the data are
available .

B.  Dagwood Sandwich

The increase in AlMg straylight is also about 20% and appears to be
featureless.  This conclusion also needs to be rechecked when the correct
attitude data are available.



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