{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.654","julian_year":2026.654,"time":"2026-08-27T21:07:17.677Z","years_from_j2000":26.654,"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-18409","name":"HD 18409","class":"o9_7ib_blue_supergiant","category":"star","object_type":"O9.7Ib blue supergiant","mag":8.37,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":null,"distance_method":null,"ra_deg":45.12381,"dec_deg":62.721957,"epoch_ra_deg":45.671411,"epoch_dec_deg":62.828565,"epoch_moved_arcsec":0.086,"pm_ra_mas_yr":-0.47,"pm_dec_mas_yr":3.19,"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-18409","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"radius_solar":31.852,"spectral_type":"O9.7Ib","color_index_bv":0.419,"radial_velocity_km_s":-42.3,"spectral_type_source":"SIMBAD (2011ApJS..193...24S, quality C)","surface_gravity_log_g":2.621,"surface_temperature_k":17372,"proper_motion_ra_mas_yr":-0.47,"proper_motion_dec_mas_yr":3.19,"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"},"designations":[{"catalog":"HD","designation":"HD 18409"},{"catalog":"HIP","designation":"HIP 14019"}],"source":{"id":"hyg","name":"HYG Database v4.1","url":"https://github.com/astronexus/HYG-Database","license":"CC-BY-SA-4.0"},"updated_at":"2026-08-27T19:16:43.430Z","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."}