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 Post subject: What a blooming nuisance!
PostPosted: Mon Jun 17, 2013 9:47 am 
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Joined: Mon Oct 12, 2009 6:47 pm
Posts: 1250
Location: Bolton
Looking at my image of comet PanSTARRS taken from the Bradford Robotic Telescope on Saturday night, I was dismayed to see that it was all but masked by "blooming" in the CCD, since it was due North and very close to the bright star Kochab (Beta Ursae Minoris).
This effect arises in a CCD when the photons from a bright star over-fill a CCD pixel, and then the excess charge leaks through into adjacent cells in the same column:
Attachment:
File comment: CCD blooming appears on the bright stars in this 120-sec image
blooming.jpg
blooming.jpg [ 31.23 KiB | Viewed 3663 times ]

Now IRIS has a neat routine to deal with problem columns (or lines) in a CCD image - running the REPAIRX command a few times removed some of the effects, and then I could deal with the residual using "bucket fill" in MS Paint.
I've loaded the repaired image into our Gallery:
http://www.boltonastro.co.uk/gallery/displayimage.php?pid=1285&fullsize=1


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