The Michelle ARRAY_TESTS recipe averages two bias frames, sets the
observation type to BIAS for the result, and files the mean bias frame
in the calibration system. The filed frame includes the observation
number in its name.
[MICHELLE/_ARRAY_TEST_STATISTICS_, _FILE_BIAS_]
Likewise the UIST ARRAY_TESTS recipe averages a group of bias frames
and sets its variance to a population variance estimate. The mean
bias frame filed with the calibration system includes the group number
in its name.
[UIST/_BIAS_GROUP_]
ORAC-DR -- imaging data reduction