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Variation of Al.1 Straylight With Pointing

Image name: ThinAl_stray_vs_ATT.png (click image to enlarge)
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Date submitted: 04-Nov-1996

                                                          4-Nov-96
							  L. Acton

		VARIATION OF Al.1 STRAYLIGHT WITH POINTING

The data shown here were taken from just over 100 thin aluminum images with
the same nominal (3 arcmin west offpoint) pointing.  The raw
(sxt_compressed) signals were averaged over the areas indicated on the
figure.  The data were not decompressed nor dark-corrected because of
memory limitations -- but it doesn't make any difference for this analysis.

I conclude from fits to these data that for Al.1:

	1) A pihnole straylight change of 1 DN corresponds to a pointing
	shift in either Y or sqrt(Y^2 + X^2) of 2 FR pixels or 5 arcsec.

	2) A lower right straylight change of 1 DN corresponds to a
	pointing shift in X of 13 FR pixels or about 30 arcsec.

I recommend a value of 3 for the Al.1 Dlt-Pnt parameter in mk_sfc.param.	

A compressed genx file with all the plots from this work is in

        /ys/sxt/doc/ThinAl_stray_vs_ATT.genx.Z

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