[KIDS] ccd Crosstalk

[agrado]

Hi Ewout,

On Tue, 08 May 2012 12:11:24 +0200, "Ewout M. Helmich"
<helmich at astro.rug.nl> wrote:
> Hi Lino,
> 
> There is a difference between measuring the crosstalk and correcting for

> it. 

indeed I was speaking about correction.
But you answer triggered a question also about measuring: what about the
case of very crowded fields ? (ok this is a special, rare case but still
possible to happen).
 
>Two things will likely happen:
> 
> 1) Your example would produce outliers in the fit to measure crosstalk 
> for all "overlapping" pixels (this in both plots #95 -> #96 and #96 -> 
> #95). Presumably the overall fits will not be affected much because 
> clipping is done before the fit. There will be other (and more) pixels 
> with e.g. value 40000ADU that fall on the background in the other CCD 
> rather than another star.
> 
> 2) Saturated pixels in #96 will be affected by crosstalk from #95, and 
> therefore you get a comparable issue as happens on the low end when 
> negative crosstalk is larger than the bias level: you get a dark spot on

> top of the saturated star in #96.

I was thinking to the case where you do not have saturation, just two
sources in the same place in the two ccds and each is affected by the value
of the other source. May be I am wrong but in this case seems to me that
you can not recover the right values.

ciao

Lino

> 
> Regards,
> Ewout
> 
> On 05/08/2012 11:51 AM, agrado wrote:
>> Dear Ewout,
>>
>> There is something about crosstalk that it is not clear to me. Let
>> suppose
>> that on ccd95 you have a source at a certain position and on ccd96 you
>> have
>> another source at the same position. How will be corrected the
crosstalk
>> in
>> this case?
>>
>> Thanks
>>
>> Lino
>>

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Aniello Grado, PhD

Ricercatore Astronomo
INAF- Osservatorio Astronomico di Capodimonte
Via Moiariello 16 80131 Napoli
ITALIA
Tel: 0039 0815575547
Fax: 0039 0815575433

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