Re: weak pixels, etc.

[Andrew Bennett <andrew.bennett@ns.sympatico.ca>]

On Fri, 8 Feb 2002 09:48:20 -0700, <aah@nofs.navy.mil> wrote:
> ...
>  I still don't understand the problem with weak pixels.
>Andrew says:
>>Not in this case! The defect is hard to see on both the Darks
>>and the Flats but is much more obvious (i.e. I found it when I
>>knew exactly where to look) on an actual image. It looks as though
>>electrons smear out over the full affected length of the column
>>(or is that row? It's vertical on my plot: AXIS2 direction)
>This doesn't make sense to me, unless what he is experiencing is
>blooming.  I'd like to see four images posted:  a raw, a flat,
>a dark, and the processed image for one of these cases.  Again,
>processing is supposed to make all pixels equal.  If this is not
>the case, then something is wrong.
>Arne

Yes - it looks like some sort of blooming (says he, not
knowing the precise definition of the term.)

An obvious example is to be found near X1=1960, X2=712
raw coordinates, FITS style, counting from 1, in file
hira2199915.fits. The smeared columns are X1=1960,61,62
starting abruptly at X2=459 and extending to the data
cutoff at X2=2032.

Perhaps somebody with the appropriate software could
crop out this bit from this image and from a corresponding
raw flat (e.g. hira2244571.fits) and dark (e.g. hira2244620.fits)
for us? I don't have suitable software at the moment.

Andrew Bennett, Avondale Vineyard