{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.668","julian_year":2026.668,"time":"2026-09-01T20:33:45.687Z","years_from_j2000":26.668,"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-4947","name":"HD 4947","class":"a2_white_star","category":"star","object_type":"A2 white star","mag":7.2,"mag_band":"V","abs_mag":0.161,"abs_mag_band":"V","distance_ly":834.1596130475685,"distance_method":"parallax","ra_deg":13.188435,"dec_deg":68.865801,"epoch_ra_deg":13.616624,"epoch_dec_deg":69.011704,"epoch_moved_arcsec":0.135,"pm_ra_mas_yr":3.51,"pm_dec_mas_yr":-3.66,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Cassiopeia","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-4947","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"age_years":383867060,"mass_solar":2.349,"radius_solar":2.264,"spectral_type":"A2","color_index_bv":0.1,"luminosity_solar":75.09309424540648,"radial_velocity_km_s":0,"spectral_type_source":"SIMBAD (1993yCat.3135....0C, quality E)","surface_gravity_log_g":4.134,"surface_temperature_k":9614,"proper_motion_ra_mas_yr":3.51,"proper_motion_dec_mas_yr":-3.66,"stellar_parameters_method":"Gaia DR3 model fit (GSP-Phot, FLAME; RUWE ≤ 1.4) — low confidence: above 7,500 K GSP-Phot's temperature and extinction are degenerate","bolometric_luminosity_solar":39.8192},"designations":[{"catalog":"HD","designation":"HD 4947"},{"catalog":"HIP","designation":"HIP 4116"}],"source":{"id":"hyg","name":"HYG Database v4.1","url":"https://github.com/astronexus/HYG-Database","license":"CC-BY-SA-4.0"},"updated_at":"2026-08-30T09:56:50.739Z","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."}