Steward Observatory Bok Telescope 90Prime Camera
Data from 09/11/2013

Observations were taken in clear, non-photometric conditions. The field
observed is the central point of the CFHT W1 field at RA=34.5d DEC=-7d.
The seeing was roughly 1.3".

Details of the 90Prime camera and detector are given here:
http://cameras.itl.arizona.edu/Detectorinformation.html

The list of images are:
bok.000[1-3].fits : 300s exposures in g-band
bok.000[5-8].fits : 300s exposures in r-band


The images have been detrended according to the following steps:

1. A mean bias level for each amplifier was removed with the IRAF colbias
   task.

2. A 2D bias frame was created from 10 bias exposures taken at the beginning
   of the night and then subtracted from the science images to remove residual
   bias structure.

3. Flat field images were generated from dome flat sequences obtained at the
   end of the night, and then divided from the science images.

4. SExtractor was used to identify object detections and construct a smooth
   background model from the sky pixels. The smooth background was then
   normalized and divided from the images as a crude correction to large-scale
   flat field variations.

5. Small corrections were applied to the nominal WCS provided in the image
   headers at the telescope to approximately align the images with SDSS stars
   in the field.


The image units are in ADU and the per-amplifier gains are provided in the
FITS headers. No photometric or astrometric calibration was performed (beyond
the first-order shifts applied to the WCS).


Notes:

* No guiding was enabled at the telescope during the 5min. exposures. The
  Bok has very stable tracking; however, there may be slight trailing due to
  the lack of guiding. SCUSS, e.g., used 150s exposures and did not report
  trailing issues.

* It was not possible to obtain sky flats because of weather constraints.
  Furthermore, the telescope was only on-sky for a few hours at the end of
  the last night of the run due to storm activity in early September, thus
  there are no images from which to obtain supersky flats. The flat-fielding
  is probably not optimal and not reflective of the calibration uncertainty
  that could be achieved under better conditions.


Contact information:
Ian McGreer      imcgreer@as.arizona.edu   520-626-1476
Xiaohui Fan      fan@as.arizona.edu        520-626-7558