{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.663","julian_year":2026.663,"time":"2026-08-31T03:28:32.542Z","years_from_j2000":26.663,"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-128167","name":"28 σ Boo","class":"f4vkf2mf1_yellow_white_main_sequence_star","category":"star","object_type":"F4VkF2mF1 yellow-white main-sequence star","mag":4.47,"mag_band":"V","abs_mag":3.472,"abs_mag_band":"V","distance_ly":51.639686971136555,"distance_method":"parallax","ra_deg":218.67,"dec_deg":29.74513,"epoch_ra_deg":218.963196,"epoch_dec_deg":29.628209,"epoch_moved_arcsec":6.143,"pm_ra_mas_yr":188.32,"pm_dec_mas_yr":132.72,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Boötes","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-128167","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"14347+2945","companions":[{"measured":2023,"magnitude":10.66,"components":"AB","discoverer_code":"STT 582","separation_arcsec":212.8,"position_angle_deg":86},{"measured":2020,"magnitude":12.08,"components":"AC","discoverer_code":"STT 582","separation_arcsec":221,"position_angle_deg":103}],"spectral_type":"F4VkF2mF1","uncertainties":{"metallicity_fe_h":[0.106,0.106]},"color_index_bv":0.364,"luminosity_solar":3.5579513055974274,"metallicity_fe_h":-0.39,"radial_velocity_km_s":0.9,"spectral_type_source":"SIMBAD (2001AJ....121.2148G, quality C)","surface_gravity_log_g":4.29,"surface_temperature_k":6722,"metallicity_fe_h_source":"Median of 18 spectroscopic determinations in 27 papers, compiled from the literature (PASTEL, Soubiran+ 2016); the error bar is the scatter between them","proper_motion_ra_mas_yr":188.32,"proper_motion_dec_mas_yr":132.72,"stellar_parameters_method":"Spectroscopic determinations compiled from the literature (PASTEL, Soubiran+ 2016)"},"designations":[{"catalog":"Bayer/Flamsteed","designation":"28 Sigma Boo"},{"catalog":"Gliese","designation":"Gl 557"},{"catalog":"HD","designation":"HD 128167"},{"catalog":"HIP","designation":"HIP 71284"},{"catalog":"HR","designation":"HR 5447"}],"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."}