For now, this Pipeline Stage computes a depth map using the DR1 method,
which takes the mean magnitude of objects close to 5-sigma S/N.

In the future we will add the calculation of other diagnostic maps
like airmass for use in systematics tests and covariance mode projection.

DM may in the future provide tools we can use in place of the methods
used here, but not on the DC2 timescale.

This is a companion discussion topic for the original entry at quay.io/eiffl/txpipe/TXDiagnosticMaps