{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.673","julian_year":2026.673,"time":"2026-09-03T16:02:15.345Z","years_from_j2000":26.673,"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-164402","name":"HD 164402","class":"b0ib_blue_white_supergiant","category":"star","object_type":"B0Ib blue-white supergiant","mag":5.72,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":null,"distance_method":null,"ra_deg":270.47658,"dec_deg":-22.780298,"epoch_ra_deg":270.883422,"epoch_dec_deg":-22.78084,"epoch_moved_arcsec":0.08,"pm_ra_mas_yr":-0.49,"pm_dec_mas_yr":-2.95,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Sagittarius","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-164402","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"18019-2247","companions":[{"measured":1998,"magnitude":12.8,"components":"AB","discoverer_code":"BU  283","separation_arcsec":8.3,"position_angle_deg":238},{"measured":1999,"magnitude":14,"components":"AC","discoverer_code":"BU  283","separation_arcsec":13.6,"position_angle_deg":33},{"measured":1999,"magnitude":14,"components":"AD","discoverer_code":"FOX9030","separation_arcsec":24.5,"position_angle_deg":265}],"radius_solar":32.754,"spectral_type":"B0Ib","color_index_bv":-0.03,"radial_velocity_km_s":-13,"spectral_type_source":"SIMBAD (2024A&A...690A.176N, quality C)","surface_gravity_log_g":2.604,"surface_temperature_k":17366,"proper_motion_ra_mas_yr":-0.49,"proper_motion_dec_mas_yr":-2.95,"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 164402"},{"catalog":"HIP","designation":"HIP 88298"},{"catalog":"HR","designation":"HR 6716"}],"source":{"id":"hyg","name":"HYG Database v4.1","url":"https://github.com/astronexus/HYG-Database","license":"CC-BY-SA-4.0"},"updated_at":"2026-09-02T19:50:56.720Z","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."}