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<pre>Yes I was wrong in stating the exposure level didn't change. I think I
looked at u' band images for CCD 65 for that. The CCDs in the corners of
the mosaic, in u' do not show much of a gain change, but in the centers
and for all CCDs in the z' filter the change is clear.
Ewout
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On 04/14/2011 09:22 AM, Konrad Kuijken wrote:
<blockquote
cite="mid:13D76DBA-9589-48EB-9389-F72DD7BB8E17@strw.leidenuniv.nl"
type="cite">
<div><br>
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<div><font class="Apple-style-span" color="#000000"><br>
</font><span></span><br>
<span>- when comparing similar exposures with different
electronic filter </span><br>
<span>settings in fact 31 out of 32 chips show signal changes
corresponding to </span><br>
<span>gain change deduced from the "gain recipe". So it seems
gain recipe </span><br>
<span>works well, and there is indeed a different effective
gain for different </span><br>
<span>filter settings.</span><br>
<span></span><br>
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<div>Hi Edwin,</div>
<div>THe fact that the gain recipe gives different results for
different filter settings does NOT necessarily mean the gain
changed. The recipe assumed that the filter does not have any
smoothing effect but this may be wrong. So photometric tests of
the gain are very important. </div>
<div>Can we do this test quickly?</div>
<div>Koen</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
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<blockquote type="cite">
<div><span>All this will be further investigated coming days.</span><br>
<span></span><br>
<span>its amazing we can already do all those things!!</span><br>
<span></span><br>
<span>When involving astrometry, which we can , we can even
have a look at </span><br>
<span>gain changes over the fov and and make fisrt guess of
illumination </span><br>
<span>correction. Will be done coming days.</span><br>
<span></span><br>
<span>Edwin</span><br>
<span></span><br>
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