{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.680","julian_year":2026.68,"time":"2026-09-06T07:22:30.178Z","years_from_j2000":26.68,"frame":"date","applied":"Proper motion, then precession and nutation. The catalogued J2000 position is carried along the great circle the object's own published motion puts it on, at a constant velocity, and the result is referred to the true equator and equinox of this instant. Those are separate things: the motion moves the object, and the rotation turns the grid under it by about fifty arcseconds a year, with nutation adding up to another seventeen.","excluded":"Parallax, the radial-velocity perspective term, aberration and refraction; each is below the accuracy of the catalogued positions themselves. An object with no published proper motion comes back where the catalogue has it rather than at a fabricated zero, and says so with a null pm_ra_mas_yr. A body with no fixed position is not propagated at all — its place comes from an ephemeris, which is what /api/v1/visible answers with."},"slug":"hd-20477","name":"HD 20477","class":"g0_yellow_star","category":"star","object_type":"G0 yellow star","mag":7.52,"mag_band":"V","abs_mag":4.042,"abs_mag_band":"V","distance_ly":161.7840003515917,"distance_method":"parallax","ra_deg":49.58328,"dec_deg":18.171623,"epoch_ra_deg":49.963928,"epoch_dec_deg":18.269188,"epoch_moved_arcsec":3.541,"pm_ra_mas_yr":-82.92,"pm_dec_mas_yr":-103.63,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Aries","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-20477","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"03183+1810","age_years":10249948500,"companions":[{"measured":2019,"magnitude":8.3,"components":null,"discoverer_code":"OCC 910","separation_arcsec":0.4,"position_angle_deg":142}],"mass_solar":0.997,"radius_solar":1.373,"spectral_type":"G0","uncertainties":{"metallicity_fe_h":[0.05,0.05]},"color_index_bv":0.642,"luminosity_solar":2.1047474886559754,"metallicity_fe_h":0.08,"radial_velocity_km_s":0,"spectral_type_source":"SIMBAD (1993yCat.3135....0C, quality E)","surface_gravity_log_g":4.152,"surface_temperature_k":5750,"metallicity_fe_h_source":"One spectroscopic determination, compiled from the literature (PASTEL, Soubiran+ 2016)","proper_motion_ra_mas_yr":-82.92,"proper_motion_dec_mas_yr":-103.63,"stellar_parameters_method":"Gaia DR3 model fit (GSP-Phot, FLAME; RUWE ≤ 1.4)","bolometric_luminosity_solar":1.8316},"designations":[{"catalog":"HD","designation":"HD 20477"},{"catalog":"HIP","designation":"HIP 15381"}],"source":{"id":"hyg","name":"HYG Database v4.1","url":"https://github.com/astronexus/HYG-Database","license":"CC-BY-SA-4.0"},"updated_at":"2026-09-02T19:50:56.720Z","attribution":"Data from SpaceCatalog.org. Individual records carry their source and license in `source`; attribution is required for CC-BY and CC-BY-SA rows."}