apply_precession¶
- rubin_sim.utils.apply_precession(ra, dec, epoch=2000.0, mjd=None)¶
apply_precession() applies precesion and nutation to coordinates between two epochs. Accepts RA and dec as inputs. Returns corrected RA and dec (in degrees).
Assumes FK5 as the coordinate system units: ra_in (degrees), dec_in (degrees)
The precession-nutation matrix is calculated by the palpy.prenut method which uses the IAU 2006/2000A model
@param [in] ra in degrees
@param [in] dec in degrees
@param [in] epoch is the epoch of the mean equinox (in years; default 2000)
@param [in] mjd is an instantiation of the ModifiedJulianDate class representing the date of the observation
@param [out] a 2-D numpy array in which the first row is the RA corrected for precession and nutation and the second row is the Dec corrected for precession and nutation (both in degrees)