{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.669","julian_year":2026.669,"time":"2026-09-02T10:21:22.476Z","years_from_j2000":26.669,"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-21641","name":"HD 21641","class":"b8_5v_blue_white_main_sequence_star","category":"star","object_type":"B8.5V blue-white main-sequence star","mag":6.77,"mag_band":"V","abs_mag":0.05,"abs_mag_band":"V","distance_ly":719.9921607479773,"distance_method":"parallax","ra_deg":52.888035,"dec_deg":47.862416,"epoch_ra_deg":53.363105,"epoch_dec_deg":47.953756,"epoch_moved_arcsec":0.895,"pm_ra_mas_yr":20.35,"pm_dec_mas_yr":-26.7,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Perseus","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-21641","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"03316+4752","age_years":372322800,"companions":[{"measured":2015,"magnitude":10.67,"components":"AB","discoverer_code":"STT  56","separation_arcsec":33.4,"position_angle_deg":352},{"measured":2015,"magnitude":12.78,"components":"AC","discoverer_code":"WAL  23","separation_arcsec":45.6,"position_angle_deg":47}],"mass_solar":2.586,"radius_solar":2.666,"spectral_type":"B8.5V","color_index_bv":-0.027,"luminosity_solar":83.17637711026708,"radial_velocity_km_s":7.6,"spectral_type_source":"SIMBAD (2012ApJ...752...58Z, quality C)","surface_gravity_log_g":3.865,"surface_temperature_k":9999,"proper_motion_ra_mas_yr":20.35,"proper_motion_dec_mas_yr":-26.7,"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":63.7511},"designations":[{"catalog":"HD","designation":"HD 21641"},{"catalog":"HIP","designation":"HIP 16430"}],"source":{"id":"hyg","name":"HYG Database v4.1","url":"https://github.com/astronexus/HYG-Database","license":"CC-BY-SA-4.0"},"updated_at":"2026-09-01T22:58:55.274Z","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."}