{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.686","julian_year":2026.686,"time":"2026-09-08T10:52:29.585Z","years_from_j2000":26.686,"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-154831","name":"HD 154831","class":"a0iv_white_subgiant","category":"star","object_type":"A0IV white subgiant","mag":7.79,"mag_band":"V","abs_mag":1.72,"abs_mag_band":"V","distance_ly":533.807423310263,"distance_method":"parallax","ra_deg":257.13531,"dec_deg":-20.217531,"epoch_ra_deg":257.533268,"epoch_dec_deg":-20.252676,"epoch_moved_arcsec":0.355,"pm_ra_mas_yr":6.22,"pm_dec_mas_yr":-11.76,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Ophiuchus","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-154831","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"17085-2013","age_years":260216440,"companions":[{"measured":2015,"magnitude":11.31,"components":"AB","discoverer_code":"HJ 4922","separation_arcsec":22.9,"position_angle_deg":311},{"measured":2015,"magnitude":13.5,"components":"AC","discoverer_code":"BU 1457","separation_arcsec":24.9,"position_angle_deg":263}],"mass_solar":2.336,"radius_solar":2.06,"spectral_type":"A0IV","color_index_bv":0.177,"luminosity_solar":17.864875748520507,"radial_velocity_km_s":0,"spectral_type_source":"SIMBAD (1988MSS...C04....0H, quality C)","surface_gravity_log_g":4.035,"surface_temperature_k":9927,"proper_motion_ra_mas_yr":6.22,"proper_motion_dec_mas_yr":-11.76,"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":35.2613},"designations":[{"catalog":"HD","designation":"HD 154831"},{"catalog":"HIP","designation":"HIP 83873"}],"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."}