{"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":"2026-09-02T03:30:28.611Z","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-21806","name":"HD 21806","class":"b1v_n_blue_white_main_sequence_star","category":"star","object_type":"B1V(n) blue-white main-sequence star","mag":7.77,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":null,"distance_method":null,"ra_deg":53.66061,"dec_deg":63.888929,"epoch_ra_deg":54.248853,"epoch_dec_deg":63.978748,"epoch_moved_arcsec":0.065,"pm_ra_mas_yr":-2.42,"pm_dec_mas_yr":0.17,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Camelopardalis","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-21806","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"radius_solar":7.597,"spectral_type":"B1V(n)","color_index_bv":0.247,"radial_velocity_km_s":-22,"spectral_type_source":"SIMBAD (1971ApJS...23..257W, quality C)","surface_gravity_log_g":3.614,"surface_temperature_k":19763,"proper_motion_ra_mas_yr":-2.42,"proper_motion_dec_mas_yr":0.17,"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"},"designations":[{"catalog":"HD","designation":"HD 21806"},{"catalog":"HIP","designation":"HIP 16684"}],"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."}