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Effect of Poor Straylight Image

Image name: Poor_Straylight_Correction.png (click image to enlarge)
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Date submitted: 09-Dec-1994

This figure illustrates the effect of using a badly prepared
straylight image.  In this case for long exposure AlMg FFI.
Note that the dark frame is very flat, except for the dark spikes.
The 23-Feb-94 straylight frame (prepared by LWA!) has clearly been 
prepared without proper correction, or more likely, the CCD response
to visible light has changed in the meantime.  In any case, the vertical
stripes at the two sides of the LEAK-SUB corrected image demonstrate the
challenges of getting all of the corrections proper for these long exposures.
The DARK_SUB image reveals lots of over-corrected dark spikes.  I think the
only way to get around this problem is by de-spiking the corrected image.
                                                              L. Acton 12/9/94

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