def transform_celestial(coords, systems): lons, lats = np.radians(coords['lon']), np.radians(coords['lat']) out = Table() out['lon'] = np.zeros(len(coords), dtype='float64') out['lat'] = np.zeros(len(coords), dtype='float64') for ii, (lon, lat) in enumerate(zip(lons, lats)): # First convert to FK5 J2000 in all cases if systems['in'] == 'fk4': lon, lat = slalib.sla_fk45z(lon, lat, 2000.0012775136652) elif systems['in'] == 'icrs': lon, lat = slalib.sla_hfk5z(lon, lat, 2000)[:2] elif systems['in'] == 'galactic': lon, lat = slalib.sla_galeq(lon, lat) elif systems['in'] == 'ecliptic': lon, lat = slalib.sla_ecleq(lon, lat, 51544) # Now convert from FK5 J2000 to out system if systems['out'] == 'fk4': # FK5 -> FK4 at BEPOCH 2000 assuming no proper motion or parallax lon, lat = slalib.sla_fk54z(lon, lat, 2000.0012775136652)[:2] elif systems['out'] == 'icrs': # FK5 -> Hipparcos (i.e. ICRF, which is as close as SLALIB # gets to ICRS) at epoch 2000 and with no proper motion lon, lat = slalib.sla_fk5hz(lon, lat, 2000) elif systems['out'] == 'galactic': # FK5 -> Galactic lon, lat = slalib.sla_eqgal(lon, lat) elif systems['out'] == 'ecliptic': # FK5 -> Ecliptic at TDB (MJD) 51544 (i.e. J2000) lon, lat = slalib.sla_eqecl(lon, lat, 51544) out[ii]['lon'] = np.degrees(lon) out[ii]['lat'] = np.degrees(lat) return out
def convert(coords, systems): if not set(systems.values()).issubset(SUPPORTED_SYSTEMS): return None lons, lats = np.radians(coords['lon']), np.radians(coords['lat']) for ii, (lon, lat) in enumerate(zip(lons, lats)): # First convert to FK5 J2000 in all cases if systems['in'] == 'fk4': lon, lat = slalib.sla_fk45z(lon, lat, 2000.0012775136652) elif systems['in'] == 'icrs': lon, lat = slalib.sla_hfk5z(lon, lat, 2000)[:2] elif systems['in'] == 'galactic': lon, lat = slalib.sla_galeq(lon, lat) elif systems['in'] == 'ecliptic': lon, lat = slalib.sla_ecleq(lon, lat, 51544) # Now convert from FK5 J2000 to out system if systems['out'] == 'fk4': # FK5 -> FK4 at BEPOCH 2000 assuming no proper motion or parallax lon, lat = slalib.sla_fk54z (lon, lat, 2000.0012775136652)[:2] elif systems['out'] == 'icrs': # FK5 -> Hipparcos (i.e. ICRF, which is as close as SLALIB # gets to ICRS) at epoch 2000 and with no proper motion lon, lat = slalib.sla_fk5hz(lon, lat, 2000) elif systems['out'] == 'galactic': # FK5 -> Galactic lon, lat = slalib.sla_eqgal(lon, lat) elif systems['out'] == 'ecliptic': # FK5 -> Ecliptic at TDB (MJD) 51544 (i.e. J2000) lon, lat = slalib.sla_eqecl(lon, lat, 51544) lons[ii], lats[ii] = lon, lat return dict(lon=np.degrees(lons), lat=np.degrees(lats))