Re: weak pixels, etc.

[Robert Creager <robert@carolinecreager.com>]

Hey Folks,

I've put up png images of the region 1940:1980,
700:750 from the images Andrew indicated at
http://www.carolinecreager.com/tass.  The images with
an e at the end have been histogram equalized to show
the abnormality better.  If anyone wants something
different (image type, size, region, etc...) just ask.

Later,
Rob

---- Andrew Bennett <andrew.bennett@ns.sympatico.ca>
wrote:
> 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
> 
> 
>