[Comm2011] Image quality VST

[Edwin A. Valentijn]

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
>

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Prof. Dr. Edwin A. Valentijn       University of Groningen
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