[Comm2011] Fwd: PPRS-041604-Closed-VST-OMEGACAM-detector 93, takes only bias images-Science Operations

[Konrad Kuijken]

Begin forwarded message:

> From: Paranal_AREmail <esoarspl at eso.org>
> Subject: PPRS-041604-Closed-VST-OMEGACAM-detector 93, takes only bias images-Science Operations
> Date: November 19, 2011 21:54:20 GMT+01:00
> To: kuijken at strw.leidenuniv.nl
> Reply-To: Paranal_AREmail <esoarspl at eso.org>
> 
> Ticket PPRS-041604 in the Paranal PRS has now been closed.
> A description of the problem, including its resolution, is listed below.
> 
> 
> Problem Number  : PPRS-041604
> 
> Creation Date   : 2011-09-11 01:47:04  by Thomas Szeifert  (vst at eso.org)
> Type            : Problem
> Keywords        : detector 93, takes only bias images
> Priority        : Necessary
> Deadline        : 
> Status          : Closed
> 
> -----  Minor Change Section ---------------------
> 
> -------------------------------------------------
> 
> Location             : VST
> Area/Instrument Type : INSTRUMENTS
> System/Instrument    : OMEGACAM
> Sub-system           : DETECTORS
> 
> Assigned to Group    : Science Operations
> Assigned to Person   : 
> CC List              :
> odt at eso.org 
> kuijken at strw.leidenuniv.nl
> uweilenm at eso.org 
> msterzik at eso.org 
> vst at eso.org
> par-vst at eso.org 
> akaufer at eso.org 
> par-tios at eso.orgVst_Omega_Notification 
> acarlier at eso.org
> 
> Telescope Downtime   : 00:00
> Workload (hrs.)      : 16
> Detailed Description :
> detector 92 doesn't detect the sky or stars - it's all on the bias level now
> 
> -----  Worklog & Comments Section ---------------
> 
> Worklog and Comments : 
>   2011-09-11 19:54:02   vst
>      The problem is persistent, no light on any fits files of detector. It is actually detector 93 (one of the 4 detectors of the row where the cross talk problems were reported in earlier runs), TSz
>   2011-09-12 18:22:22   jvalenzu
>      CCD #93 shows only level bias.
> 
>      * After checking that the CCD #93 (CH0 - Board #3 FIERA 2) with an exposure time around 1 sec, the level bias is around 130 counts. No sensibility to the light. 
>      * A swapping between CH0 and CH1 in the Video board showed that the image continued in the same place in the RTD. With our experience, normally this indicates that problem is in the video board amplifier.
>      *The video board was replaced. After connecting again, the image continued with the bias level.
>      *A new external cable video from the preamplifier to the video board was connected and the image came back to the RTD with the similar values that the others CCD's.
>      *However, with the original cable and moving the preamflifier connector the image appeared in the same position. Clearly, we have two possibilities: problem in the cable connector or bad connection in the preamplifier connector. Waiting for authorization from Garching to do the intervention.
>      *At the moment, the CCD93 is working fine with the original cable but it is possible to break down the channel again
> 
>      JVA/MAS
>   2011-09-12 22:45:32   vst
>      At the time of the twilight flats there is still no light detected by detector 93, it worked only for a short time. TSz
>   2011-09-19 12:33:44   mriquelm
>      Finally the culprit one  was the video cable, not one but three times. Previously the pre-amplifier was replaced by the spare one, therefore there will be some slight changes in the BIAS level for the FIERA 2 Sci detectors.  Now the detector 93 is behaving normally. Ticket re-assigned to SciOps in order to report if the new BIAS level are acceptable or needs to be adjusted.
> 
>      For the record: The original pre-amps is functional and has been stored as spare.
> 
>      Assigned to Group Changed: Science Operations 
>      Priority Changed: Necessary 
>      Status Changed: Assigned 
>      Modified By: mriquelm 
>      Modified Date: 2011-09-19 12:33:44 
>      Assigned to Group Changed: Science Operations 
>      Priority Changed: Necessary 
>      Status Changed: Assigned 
>      Modified By: mriquelm 
>      Modified Date: 2011-09-19 12:33:44 
>   2011-09-19 13:34:15   vst
>      Hello,
>      for the time being no large jump can be seen in the bias levels. It looks OK.
>      However it needs to be monitored the next days too.
>      I am putting on hold the ticket.
>      Cheers,
>      Christophe M.
> 
>      Status Changed: On Hold 
>      Modified By: vst 
>      Modified Date: 2011-09-19 13:34:15 
>      Status Changed: On Hold 
>      Modified By: vst 
>      Modified Date: 2011-09-19 13:34:15 
>   2011-11-19 20:52:52   antu
>      Not observed again. I close the ticket
>      -Steffen
> 
>      Status Changed: Closed 
>      Modified By: antu 
>      Modified Date: 2011-11-19 20:52:52 
>      Status Changed: Closed 
>      Modified By: antu 
>      Modified Date: 2011-11-19 20:52:52 
> 
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