Interpretation of the bitmask column

The ccds- and survey- files described on the files page contain a column bitmask, which is defined as:

Bit Meaning
0001 this exposure is flagged in the bad_expid file
0010 a zeropoint solution was not computed for these exposures, and so the ccdname disagrees with the hdu number
0100 these ccds had outlying values for astrometric or photometric offsets (\(\sqrt(\) ccdrarms \(^2 +\) ccddecrms \(^2) > 0.1\) OR ccdphrms \(> 0.2\))

The CCDs used by legacypipe can be determined via:

photometric == True AND bitmask == 0

Note that photometric, ccdrarms, ccddecrms and ccdphrms are all columns in the ccds- and survey- files described on the files page.