{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.665","julian_year":2026.665,"time":"2026-08-31T18:47:54.999Z","years_from_j2000":26.665,"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-16855","name":"HD 16855","class":"a2_white_star","category":"star","object_type":"A2 white star","mag":6.77,"mag_band":"V","abs_mag":2.079,"abs_mag_band":"V","distance_ly":282.8764048628647,"distance_method":"parallax","ra_deg":40.897335,"dec_deg":43.537968,"epoch_ra_deg":41.334022,"epoch_dec_deg":43.651916,"epoch_moved_arcsec":2.198,"pm_ra_mas_yr":78.94,"pm_dec_mas_yr":-23.79,"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-16855","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"age_years":1148290000,"mass_solar":1.698,"radius_solar":2.143,"spectral_type":"A2","color_index_bv":0.263,"luminosity_solar":12.835121968394969,"radial_velocity_km_s":20,"spectral_type_source":"SIMBAD (1993yCat.3135....0C, quality E)","surface_gravity_log_g":3.903,"surface_temperature_k":7386,"proper_motion_ra_mas_yr":78.94,"proper_motion_dec_mas_yr":-23.79,"stellar_parameters_method":"Gaia DR3 model fit (GSP-Phot, FLAME; RUWE ≤ 1.4) — low confidence: Gaia's classifier calls the source a binary, which GSP-Phot fitted as one star","bolometric_luminosity_solar":11.1558},"designations":[{"catalog":"HD","designation":"HD 16855"},{"catalog":"HIP","designation":"HIP 12725"}],"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."}