SMARTS optical images are processed with the IRAF task CCDPROC using a bias prepared with the IRAF task ZEROCOMBINE and a domeflat or skyflat prepared with the IRAF task FLATCOMBINE. As of November 1, 2006, the SMARTS optical images are processed slightly differently. In order to remove the low-level horizontal "banding" that we have seen at times during the last six months, the overscan is now fit with a cubic spline function of order 11. All other steps remain the same. The old processing parameters can be found here.

Modified 11/01/2006

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Ten biases are taken each night and are combined into a single
bias frame using the IRAF task ZEROCOMBINE.

The IRAF task ZEROCOMBINE parameters are set as follows:

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VRI dome flats are observed every night, 10 exposures of each. 

JHK dome flats are observed every third night in rotation.  10 exposures are taken at each of the 7 dither positions (dither throw = 40).  10 additional exposures at each dither position are then taken with the dome lamps off.  The final flat at each dither position is the difference between the combined lamp-on flat minus the combined lamp-off flat. 

B sky flats are taken due to undesirable artifacts present in the B domes.  A minimum of 3 images are taken every night weather permitting.  It is required that individual skyflats have different RA and
DEC values.

In all cases, the individual flats are processed first with CCDPROC for the overscan and zero corrections, then combined with FLATCOMBINE.

FLATCOMBINE parameters are set as follows for the SKY flats:

FLATCOMBINE parameters are set as follows for the DOME flats:

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Images are processed, one filter type at a time, with a bias and a skyflat of the corresponding filter type using the IRAF task CCDPROC. The result is a processed image, prefixed with the letter "r", that have been OZF'ed (overscanned, flattened and zeroed) but not T'ed (trimmed).

When biases are not taken for a given night, the ZEROCOMBINEd bias from the nearest available night is used instead.  This bias will have already gone through CCDPROC with images of its same night. The bias section for use in overscanning was determined by IMPLOT to extend from less than 3 and more than 14, so [3:14,1:1024]) was chosen as the overscan strip image section.

When contemporaneous skyflats are not available, FLATCOMBINEd skyflats from previous nights are used instead.  These skyflats will have already been processed using their own contemporaneous biases.

The IRAF task CCDPROC parameters are set as follows:

              I R A F 
Image Reduction and Analysis Facility
PACKAGE = ccdred
   TASK = ccdproc

1.3m Observations of General-Purpose Photometric Standards and Reports of Calculated Measurements

General-purpose photometric standards are observed every photometric night on the 1.3m telescope.

The procedure is as follows:

Each photometric night, 1 Landolt field is observed ONCE in all optical filters. In addition, 2 IR standards (one blue and one red) are observed ONCE in all IR filters. Because extinction coefficients cannot be calculated on such nights, "default" values (see below)are used for calculations of zeropoints and color terms.

Periodically, more thorough observations of the same standards are performed, observing each of the 3 standard fields (1 Landolt, 2 IR fields) at 3 different airmasses in order to calculate extinction coefficients. The medians of these values, taken over many months, are the "default" extinction coefficients mentioned above.

Standard star images are available to all users and are not charged against their allocation. We do our best to choose those Landolt fields with at least 3 standard stars available in the field of view. If your program requires additional standard observations, please include them in your PhaseII submission. Additional observations are charged against your allocation.