{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.678","julian_year":2026.678,"time":"2026-09-05T12:05:13.248Z","years_from_j2000":26.678,"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-173384","name":"HD 173384","class":"a0_white_star","category":"star","object_type":"A0 white star","mag":8.69,"mag_band":"V","abs_mag":2.154,"abs_mag_band":"V","distance_ly":661.574944247887,"distance_method":"parallax","ra_deg":280.92612,"dec_deg":30.404724,"epoch_ra_deg":281.183919,"epoch_dec_deg":30.431218,"epoch_moved_arcsec":0.321,"pm_ra_mas_yr":8.11,"pm_dec_mas_yr":8.88,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Lyra","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-173384","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"18437+3024","companions":[{"measured":2015,"magnitude":9.31,"components":"AB","discoverer_code":"STF2376","separation_arcsec":22.3,"position_angle_deg":63},{"measured":2015,"magnitude":12.9,"components":"AD","discoverer_code":"SLE 112","separation_arcsec":29.1,"position_angle_deg":168},{"measured":2015,"magnitude":12.12,"components":"AC","discoverer_code":"STF2376","separation_arcsec":85.1,"position_angle_deg":206}],"spectral_type":"A0","color_index_bv":0.069,"luminosity_solar":11.978432778258552,"variable_mag_max":8.517,"variable_mag_min":8.747,"radial_velocity_km_s":0,"spectral_type_source":"SIMBAD (1993yCat.3135....0C, quality E)","proper_motion_ra_mas_yr":8.11,"proper_motion_dec_mas_yr":8.88},"designations":[{"catalog":"HD","designation":"HD 173384"},{"catalog":"HIP","designation":"HIP 91863"}],"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."}