[Comm2011] twilights at different rotator angles

[John P. McFarland]

Hi Edwin,

I had already planned on doing these exact observations, but there is a 
problem getting the Toelner to turn the lamps on since the last set of dome 
flats Tuesday morning.  We are investigating that with high priority at this 
very moment.  I will keep you informed.

Cheers,


-=John


On Wed, 8 Jun 2011, Edwin A. Valentyn wrote:

> it would be easier to interpret the ratios of dome to sky at 4 angles.
> Edwin
>
> On 8-6-2011 5:12, Gijs Verdoes Kleijn wrote:
>> Hi John and Edwin,
>>
>> As a quick check I have divided the raw twilights at different rotator
>> angles by the one at rotangle=0: see top of this page:
>> http://wiki.astro-wise.org/projects:omegacam:commissioning:flatfields
>> ~2-3% differences in twilightflats as a function of rotator angle are seen.
>>
>> I think another analysis route is needed to say more than this about
>> dependence on rotator angle. My first thought is to look again at
>> twilightflats*gain
>>
>> Best wishes, Gijs
>>
>>
>
> -- 
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> Prof. Dr. Edwin A. Valentijn       University of Groningen
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