[Comm2011] OCAM secondary standards

[Dietrich Baade]

Dear Edwin,

Thank you for this quite helpful compilation and discussion.

Would it be possible that, starting with September, every 3 months you 
give us a similar overview such as the present one so that we get some 
feedback on where we stand and a preview of what still needs to be 
done?  Obviously, the September report could (should) be part of the 
OCM3 report.

It would be helpful to add 2 more columns indicating the filters, for 
which the reduction has been finished, and the filters, for which the 
data seems to be final (it is understood that you can say this for sure 
and finally only after the celestial calibration circle has been 
completed).

Many thanks and best regards,

Dietrich.

On 8/16/2011 9:37 AM, Edwin A. Valentyn wrote:
> Dear Dietrich,
>
> Please find enclosed our first preliminary assessment of the remaining 
> work to be done on the OmegaCAM secondary Standard fields
>
> hope this clarifies
>
> kind regards
>
> Edwin Valentijn
>
>
>
>
> =======================================================================
> Note on OmegaCAM Secondary standard Programmme- CP req 569.
> =======================================================================
> The table below lists the 22 SA fields considered for OmegaCAM 
> secondary standard fields.  Out of this list 8 field will be selected. 
> The 8 preceded by an asterisk (*) are those primarily selected for 
> full RA coverage as specified in the Calibration Plan.
>
> Those fields with filter list entries in the OCM2 and OCM3 columns 
> have been observed during commissioning in the context of Req 569 
> Secondary standards and Req 548 Illumination correction. The OB covers 
> approximately 2x2 square degrees by making 32 observations with each 
> CCD centered on the specified coordinates.
>
> The number of Landolt standard stars, Stetson standard stars, SDSS DR5 
> stars and stars from the Preparatory Programme (PP) for the OmegaCAM 
> Secondary Standard Program are listed for the OmegaCAM 1.2 square 
> degree fieldsize.
>
>
>  Field   RA [deg]  Dec [deg]  Land  Stet   SDSS5    PP    OCM2    OCM3
> ------------------------------------------------------------------------
>   SA51   112.663   +29.828      0      0     214      0
>   SA57   197.171   +29.384      0      0     952      0
>   SA68     4.146   +15.844      0      0    1302      0
>  *SA92    13.946    +0.949     41    213    1094   6475          ugrizV
>   SA93    28.783    +0.824      4      0    1128      0
>   SA94    44.033    +0.571      7      0    1099      0
>  *SA95    58.500    +0.000     45    426    1093      0          ugriz
>  *SA98   103.021    -0.328     46   1116       0  23840
>   SA100  133.529    +0.546      6      1    3343      0
>  *SA101  149.112    -0.386     35    117    1776   5591
>   SA102  163.779    +0.866      5     66    1517      0
>   SA103  178.779    +0.556      2      0    1507      0
>  *SA104  190.488    -0.529     34     76    1576   5701
>   SA105  204.533    +0.676      4      0    2172      0
>   SA106  220.533    +0.427      2     15    2864      0
>  *SA107  234.825    -0.263     28    728    3889  12006  grizV
>   SA108  248.033    +0.369      6      3    6148      0
>  *SA110  280.600    +0.346     39    589       0  38562
>   SA112  310.529    +0.524      7     73   12087      0
>  *SA113  325.375    +0.499     42    483    4046  13947  ugzB    ugrizBV
>   SA114  340.529    +0.689      9      5    1957      0
>   SA115  355.779    +0.888     10      0    1170      0
>
> ------------------------------------------------------------------------
>
> The data taken in OCM2 and OCM3 are currently being investigated. 
> Preliminary indications are that OCM2 data may not be usable due to 
> telescope re-configuration and/or observing conditions. We expect to 
> have obtained  a reasonable set for the fields SA 92, 95 and 113.
>
> The OmegaCAM Calibration Plan indicates two nights bright time  each 
> month during the first year after commissioning.
>
> Now, reviewing this after our experiences and progress with the 
> various commissioning runs the following has to be taken into account:
>
> i) it takes about 8h- one night to do one field in all required bands 
> (u,g,r,i,z,B,V)
> ii) likely we will have 2-3 fields well covered by the commissioning runs
> iii) the analysis work related to this programme is more complex than 
> expected due to very large illumination corrections detected for the 
> interference filters, up to 15%. This aspect requires more cross 
> checks with redundant observations, particularly due to the noted 
> dependency of the correction on the rotator position. We are still 
> analysing the data and reviewing the approach (eg more elaborate usage 
> of dome flats).
>
> Adding the pluses and minus of the above, and taking bad weather into 
> account it seems reasonable to schedule 2 bright nights each full 
> moon, occasionally skipping ( eg august 2011) one full moon period in 
> order to smear out the remaining fields over an 8 month period.
>
> In the end this involves some relaxing of the original requirement, 
> which is good, but this can only be confirmed after we have settled 
> the procedures to accurately face the illumination corrections.
>
> =========================================================================
>

-- 
Dietrich Baade
ESO - European Organisation for Astronomical Research in the Southern Hemisphere
Karl-Schwarzschild-Strasse 2,  85748 Garching bei Muenchen,  Germany
Email: dbaade at eso.org    Tel: +49 89 3200-6388    Fax: +49 89 3202362