{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.666","julian_year":2026.666,"time":"2026-09-01T07:49:04.689Z","years_from_j2000":26.666,"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-39731","name":"HD 39731","class":"g5_yellow_star","category":"star","object_type":"G5 yellow star","mag":8.26,"mag_band":"V","abs_mag":2.559,"abs_mag_band":"V","distance_ly":450.49208124803175,"distance_method":"parallax","ra_deg":88.64927999999999,"dec_deg":5.353688,"epoch_ra_deg":89.007201,"epoch_dec_deg":5.358991,"epoch_moved_arcsec":0.345,"pm_ra_mas_yr":-8.79,"pm_dec_mas_yr":-9.48,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Orion","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-39731","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"05546+0521","age_years":502865900,"companions":[{"measured":2016,"magnitude":9.82,"components":"AB","discoverer_code":"STF 815","separation_arcsec":13.1,"position_angle_deg":137},{"measured":2015,"magnitude":9.75,"components":"AC","discoverer_code":"STF 815","separation_arcsec":85.4,"position_angle_deg":309}],"mass_solar":2.698,"radius_solar":8.74,"spectral_type":"G5","color_index_bv":0.873,"luminosity_solar":8.248975239353296,"metallicity_fe_h":0.14,"variable_mag_max":8.231,"variable_mag_min":8.341,"radial_velocity_km_s":0,"spectral_type_source":"SIMBAD (1993yCat.3135....0C, quality E)","surface_gravity_log_g":2.768,"surface_temperature_k":5237,"metallicity_fe_h_source":"One spectroscopic determination, compiled from the literature (PASTEL, Soubiran+ 2016)","proper_motion_ra_mas_yr":-8.79,"proper_motion_dec_mas_yr":-9.48,"stellar_parameters_method":"Gaia DR3 model fit (GSP-Phot, FLAME; RUWE ≤ 1.4)","bolometric_luminosity_solar":58.5524},"designations":[{"catalog":"HD","designation":"HD 39731"},{"catalog":"HIP","designation":"HIP 27932"}],"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."}