Hi Ewout,<div><br><br><div class="gmail_quote">On Tue, May 8, 2012 at 12:11 PM, Ewout M. Helmich <span dir="ltr"><<a href="mailto:helmich@astro.rug.nl" target="_blank">helmich@astro.rug.nl</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi Lino,<br>
<br>
There is a difference between measuring the crosstalk and correcting for it. </blockquote><div><br></div><div>Indeed I was speaking about correcting. But your answer triggered another question: what about case of very crowded fields? ok it is a special case but still possible to happen.</div>
<div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Two things will likely happen:<br>
<br>
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.<br>
<br>
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.<br>
<br></blockquote><div>I was not considering the case of saturated stars. You have two sources in the same place in the respective ccd. The counts of one source will affect the other and the other way around. May be I am wrong but in this case it seems to me that you cannot recover the correct values.</div>
<div><br></div><div>ciao</div><div><br></div><div>Lino </div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Regards,<br>
Ewout<div class="HOEnZb"><div class="h5"><br>
<br>
On 05/08/2012 11:51 AM, agrado wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Dear Ewout,<br>
<br>
There is something about crosstalk that it is not clear to me. Let suppose<br>
that on ccd95 you have a source at a certain position and on ccd96 you have<br>
another source at the same position. How will be corrected the crosstalk in<br>
this case?<br>
<br>
Thanks<br>
<br>
Lino<br>
<br>
</blockquote>
</div></div></blockquote></div><br></div>