Degraded trace shift when amplifier is masked #1477
Merged
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Minor PR fixing a 1 time issue that revealed an actual weakness in the pipeline.
The fit of the trace shifts includes polynomial degrees as a function of CCD coordinates that become weakly constrained when an entire amplifier is masked.
Here we detect masked amplifiers (by inspecting the FIBERSTATUS values in the fibermap) and force a degree = 0 (i.e. single scalar shift) when at least one amplifier of a CCD is masked.
Example is exposure 20211107/00107853. The sky subtraction is ok with this version of the code.