[Comm2011] OCAM2 daily log day 3

[G. Sikkema]

hi John,
I tried to analyse the illumination variations in both g and z of this 
night.
First of all: the exposures overlap is excellent for the 33 pointings...
Secondly: we have now 2x more stars in common in each chip for SA107 
compared to our previous analysis for SA110, i.e. 61 stars for SA107 and 
~30 for SA110.

Currently :
for z we need to construct a good fringe frame which may be constructed 
from the 33 pointings. I do not see illumination variations when using a 
default fringe frame, however, this default frame does not remove most 
fringes... furthermore we need skyflats in z, I use forever skyflats at 
this moment

For g: the results look reasonable. One pointing of the 33 likely had 
cirrus in its field of view because it has an offset of +0.2 mag 
compared to the others. Please compare  our previous attempt  plot 
illum_gain_corrected_gband_OCAM1B.jpg with the current  plot 
illum_gain_corrected_gband_OCAM2.jpg, and note the offset (for chip 87)

The plots show the common stars ~30 for SA110 vs 61 stars in SA107 in 
each chip.

I am curious what rotator angle was used compared to our previous attempt.


cheers,
Gert S.


John P. McFarland wrote:
> Hi All,
>
> Tonight was quite a productive night.  Unfortunately the Toelner is 
> still not responding, so no new quick checks (despite the 51 test 
> quick checks) or 4-angle dome flats.  The problem will hopefully be 
> solved today.  Andrea, Koen, and Dietrich arrived tonight and worked 
> until around midnight when I took over.
>
> The conditions were relatively good with mostly excellent 0.5-0.7 
> arcsec seeing, but somewhat poor transparency.  It is difficult to say 
> which observations will be photometrically useful.  Several polar 
> field observations were obtained, so the variable conditions should be 
> seen there as well.  Complete 32 CCD offset observations in z and g 
> were obtained for SA107.  These are almost perfect compared to the 
> last nights' sets, but there was still some very light cirrus visible 
> on the all-sky cam during these.  Also, please check the 32 CCDs 
> exposures overlap for the center of the field.  The center was placed 
> on all the CCDs in the order that they are stored in the RawFitsData.
>
> A donut template was attempted for the VST people (requested by Koen), 
> but failed due to some template keyword error (Andrea and Koen will 
> have to investigate this).  Nonetheless, the focus offsets were done 
> and the required data secured.
>
> Following this, the night was wrapped up with a 3x3 grid from the 
> newest plate system centered on about the SA113 field, taken with 
> dither,N=5 in r for 60 seconds per exposure.  Please check these out 
> to make sure all the offsets were done correctly.
>
> Cheers,
>
>
> -=John
> ------------------------------------------------------------------------
>
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-- 
dr. Gert Sikkema

Kapteyn Institute
Zernike Building, room 133
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sikkema at astro.rug.nl
homepage: http://www.astro.rug.nl/~sikkema
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