pupil_coords_from_ra_dec

rubin_sim.utils.pupil_coords_from_ra_dec(ra_in, dec_in, pm_ra=None, pm_dec=None, parallax=None, v_rad=None, include_refraction=True, obs_metadata=None, epoch=2000.0)

Take an input RA and dec from the sky and convert it to coordinates on the focal plane.

This uses PAL’s gnomonic projection routine which assumes that the focal plane is perfectly flat. The output is in Cartesian coordinates, assuming that the Celestial Sphere is a unit sphere.

The RA, Dec accepted by this method are in the International Celestial Reference System. Before applying the gnomonic projection, this method transforms those RA, Dec into observed geocentric coordinates, applying the effects of precession, nutation, aberration, parallax and refraction. This is done, because the gnomonic projection ought to be applied to what observers actually see, rather than the idealized, above-the-atmosphere coordinates represented by the ICRS.

@param [in] ra_in is in degrees (ICRS). Can be either a numpy array or a number.

@param [in] dec_in is in degrees (ICRS). Can be either a numpy array or a number.

@param [in] pm_ra is proper motion in RA multiplied by cos(Dec) (arcsec/yr) Can be a numpy array or a number or None (default=None).

@param [in] pm_dec is proper motion in dec (arcsec/yr) Can be a numpy array or a number or None (default=None).

@param [in] parallax is parallax in arcsec Can be a numpy array or a number or None (default=None).

@param [in] v_rad is radial velocity (km/s) Can be a numpy array or a number or None (default=None).

@param [in] include_refraction is a bool controlling the application of refraction.

@param [in] obs_metadata is an ObservationMetaData instantiation characterizing the telescope location and pointing.

@param [in] epoch is the epoch of mean ra and dec in julian years (default=2000.0)

@param [out] returns a numpy array whose first row is the x coordinate on the pupil in radians and whose second row is the y coordinate in radians