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Imaging Data Quality Assessment

 

The quality of each field of data from the 2.5-meter imaging camera is assessed based on a number of criteria. A quality is assigned for each criterion, and an overall quality is assigned based on the worst value of these. The possible values for quality in the class Field (Table 16) are:

For the EDR, all fields are in one of the first three categories. The quality for each field is indicated in Figure 8.

A set of flags is maintained for each field in which the quality for each of the criteria is recorded. These flags are 32-bit masks; there are 4 masks, one each for GOOD, ACCEPTABLE, HOLE, and BAD, with bits assigned for each criterion used to judge quality. For example, if the seeing is judged acceptable, then the bit assigned to seeing in the ``acceptable'' mask is set. Additionally, an overall quality is stored separately.

The following are the criteria used to assess data quality:

The parameter badMask in Table 16 encodes reasons why data were not declared GOOD.

The SKY and AMP bits are not used for the EDR. They are used to mask imaging data because of high sky values or bad amplifier noise, respectively.

A substantial portion of fields in the EDR have had quality set manually, overriding the PSF or tracking quality in most cases. A list of all fields that have had the quality overridden are listed in Table 25. They have the AR_FQ_MANUAL flag bit set.


next up previous
Next: Resolving Multiple Detections Up: Software Previous: Assessment of Photometric Calibration

Michael Strauss
Thu Jan 30 11:15:34 EST 2003