[Comm2011] Image quality VST

[Konrad Kuijken]

We're typically getting same or slightly better images than the dimm.
But the dimm is lower than the vst, so probably ground layer makes
comparison tricky in detail. But overall we're in agreement with open-
zir seeing, yes.
K

On Mar 28, 2011, at 23:05, Gijs Verdoes Kleijn wrote:

> Hi Ewout,
>
> I'm led to same conclusions as Edwin. In addition I'm impressed by  
> the FWHM=0.6arcsec seeing as minimum. This is in agreement with  
> independent measurements (e.g., DIMM)?
>
> Cheers, Gijs
> ps. FYI, I had a quick look at the rawbias counts for those ingested  
> sofar: attached median values vs extension number shown, colored by  
> MJD of DATE-OBS. Extension 32 is the odd one out/
>
> Op 28-3-2011 22:43, helmich schreef:
>> Indeed. There is going to be a meeting tonight with Pietro Shipani,  
>> to
>> discuss this. He's been sleeping through most of this since he's been
>> acting Telescope Operator.
>>
>> Ewout
>>
>> On Mon, 28 Mar 2011 22:35:04 +0200, "Edwin A. Valentyn"
>> <valentyn at astro.rug.nl>  wrote:
>>> Hm,
>>>
>>> my first reactions:
>>> - patterns are not what is expected from tilts
>>> - patterns at various rotator positions are at first order  
>>> remarkably
>>> consistent with each other; so  rotators are not causing effects;
>>> picking out the one with largest amplitude variation is 270deg,  
>>> which
>>> can be taken as representative.
>>> - at rot 270 FHWM shows allmost spherical function over the field of
>>> view, diameter of circle several degrees; it looks like some overall
>>> misalignment in telescope, (assuming rot 0 corresponds to North)  
>>> in E-W
>>> direction
>>>
>>> But I guess, you have noted the same and VST people are scratching  
>>> their
>>> head?
>>>
>>> regards
>>> Edwin
>>>
>>> On 28-3-2011 8:30, helmich wrote:
>>>> Hi,
>>>>
>>>> Here are the resulting PSF anisotropy plots for 4 images of the  
>>>> same
>>>> field taken with 0,90,180 and 270 degrees rotator. We think that  
>>>> the
>>>> dominant effect is not a tilt. Beware that the legend denoting
>>>> ellipticity at the bottom is not correct scale.
>>>>
>>>> Regards,
>>>>
>>>> Ewout
>>>>
>>> --
>>> -------------------------------------------------------------------------
>>> Prof. Dr. Edwin A. Valentijn       University of Groningen
>>> Coordinator Target                 www   : www.rug.nl/target
>>> Head OmegaCEN                      www   : www.astro.rug.nl/omegacen
>>> Kapteyn Astronomical Institute     tel   : +31 (0)50 3634011/4036  
>>> (secr)
>>> P.O.Box 800                        mobile: +31 (0)6 48276416
>>> NL-9700 AV Groningen               e-mail: valentyn at astro.rug.nl
>>> The Netherlands                    www   : www.astro.rug.nl/ 
>>> ~valentyn
>>> -------------------------------------------------------------------------
>
> -- 
> --------------------------------------------------------------------
> |dr Gijs Verdoes Kleijn         |   astronomer                     |
> |e-mail: verdoes at astro.rug.nl   |   OmegaCEN / Kapteyn Institute / |
> |www: www.astro.rug.nl/~verdoes |   Target                         |
> |tel: +31-50-3638326            |   University of Groningen        |
> |mobile: +31-654658050          |   postal address:                |
> |                               |   Kapteyn Astronomical Institute |
> |                               |   Postbus 800, 9700 AV, Groningen|
> |                               |   The Netherlands                |
> --------------------------------------------------------------------
>
> <RawBiasMedianVsExtensionByMJD.png>

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