galpy.util.coords.cov_pmrapmdec_to_pmllpmbb¶
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galpy.util.coords.
cov_pmrapmdec_to_pmllpmbb
(cov_pmradec, ra, dec, degree=False, epoch=2000.0)[source]¶ NAME:
cov_pmrapmdec_to_pmllpmbbPURPOSE:
propagate the proper motions errors through the rotation from (ra,dec) to (l,b)INPUT:
covar_pmradec - uncertainty covariance matrix of the proper motion in ra (multplied with cos(dec)) and dec [2,2] or [:,2,2]
ra - right ascension
dec - declination
degree - if True, ra and dec are given in degrees (default=False)
epoch - epoch of ra,dec (right now only 2000.0 and 1950.0 are supported when not using astropy’s transformations internally; when internally using astropy’s coordinate transformations, epoch can be None for ICRS, ‘JXXXX’ for FK5, and ‘BXXXX’ for FK4)
OUTPUT:
covar_pmllbb [2,2] or [:,2,2] [pmll here is pmll x cos(b)]HISTORY:
2010-04-12 - Written - Bovy (NYU)
2020-09-21 - Adapted for array input - Mackereth (UofT)