medianEllipticityResidualsFromCat

lsst.validate.drp.util.medianEllipticityResidualsFromCat(cat)

Compute the median ellipticty residuals from a catalog of measurements.

This function is used as an aggregate function to extract just declination from lsst.validate.drp.matchreduce.build_matched_dataset

The intent is to use this for a set of measurements of the same source but that’s neither enforced nor required.

Parameters:

cat : collection

Object with .get method for ‘e1’, ‘e2’ that returns radians.

Returns:

e1_median : float

Median real ellipticity residual.

e2_median : float

Median imaginary ellipticity residual.