[Comm2011] CCD # 92 -> #93

[Dietrich Baade]

Dear Konrad, dear All,  

Three e-mails within a minute confirming the previous mis-identification - so, this ought to be the truth.  Many thanks for the clarification (however:  how was that error possible in the first place?).  

An important secondary analysis step would it be to check whether the crosstalk patterns between 94, 95, and 96 have changed.  In the past, 93 has seemingly played a fairly minor role in this - but it might still have been a major part of the cause.  

Best regards,

Dietrich. 
________________________________________
Von: K Kuijken [kuijken at strw.leidenuniv.nl]
Gesendet: Montag, 12. September 2011 13:11
Bis: Olaf Iwert
Cc: Dietrich Baade; Javier Valenzuela; Nicolas Haddad; Miguel Riquelme; Frederic Yves Joseph Gonte; Christoph Geimer; smieske at eso.org; Gert Finger; mbernard at usm.lmu.de; Sebastian Deiries; OmegaCAM Commissioning 2011 mailinglist
Betreff: Re: AW: CCD # 92

Looking at a few images from last night: the problem is in CCD 93, not
92. So one of the ones in our troublesome quartet.
Olaf, we have all the data here - let us know if we can help with any
analysis.
Konrad


Olaf Iwert wrote:
> Hi Dietrich,
>
> Yes, I already thought about these points yesterday and verified them
> today.
>
> Before we draw more conclusions we need however more info from Paranal
> (like you said) and an assessment what works and what does not. At this
> point it could be caused by almost anything inside the amplifier and
> video chain: cables, bias voltage, video board......
> Nevertheless of course it distracts me from thinking normally, as it is
> not normal and we never saw something similar.
> When I called yesterday, noone had had time to look at the problem, due
> to other emergencies.
>
> Some answers to your questions:
>  From all information I have (not much) #92 is the correct number.
> # 92 did not show any previous problems.
> In the worst case replacement device could be Chamaeleon, but this
> device has flatness problems and is also no ideal fit to the channel
> potential. This is all we have.
> # 92 is not from a batch, where the protection diodes have been removed.
> # 92 is not in the mixed voltage group.
> # 92 is neither inside the group showing crosstalk, nor in the same
> group where we exchanged the faulty CCD in 2009.
> All spare devices are on Paranal.
>
> With best wishes
> Olaf
>