{"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":"2026-09-01T03:39:26.676Z","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-5550","name":"HD 5550","class":"a0iii_white_giant","category":"star","object_type":"A0III white giant","mag":5.97,"mag_band":"V","abs_mag":0.815,"abs_mag_band":"V","distance_ly":350.32913149484216,"distance_method":"parallax","ra_deg":14.629275,"dec_deg":66.351793,"epoch_ra_deg":15.056657,"epoch_dec_deg":66.496761,"epoch_moved_arcsec":1.211,"pm_ra_mas_yr":43.44,"pm_dec_mas_yr":-13.19,"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-5550","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"00585+6621","age_years":328204840,"companions":[{"measured":2018,"magnitude":12.5,"components":null,"discoverer_code":"TOK 802","separation_arcsec":1.5,"position_angle_deg":58}],"mass_solar":2.55,"radius_solar":2.552,"spectral_type":"A0III","color_index_bv":-0.008,"luminosity_solar":41.114972110452236,"radial_velocity_km_s":-10,"spectral_type_source":"SIMBAD (quality C)","surface_gravity_log_g":3.912,"surface_temperature_k":9999,"proper_motion_ra_mas_yr":43.44,"proper_motion_dec_mas_yr":-13.19,"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":56.6435},"designations":[{"catalog":"HD","designation":"HD 5550"},{"catalog":"HIP","designation":"HIP 4572"},{"catalog":"HR","designation":"HR 273"}],"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."}