{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.667","julian_year":2026.667,"time":"2026-09-01T13:18:27.924Z","years_from_j2000":26.667,"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":"mizar","name":"Mizar","class":"a2v_white_main_sequence_star","category":"star","object_type":"A2V white main-sequence star","mag":2.23,"mag_band":"V","abs_mag":0.129,"abs_mag_band":"V","distance_ly":85.80815525712032,"distance_method":"parallax","ra_deg":200.981205,"dec_deg":54.925362,"epoch_ra_deg":201.253327,"epoch_dec_deg":54.784941,"epoch_moved_arcsec":3.286,"pm_ra_mas_yr":121.23,"pm_dec_mas_yr":-22.01,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Ursa Major","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/mizar","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"wds_id":"13239+5456","companions":[{"measured":2022,"magnitude":3.88,"components":"AB","discoverer_code":"STF1744","separation_arcsec":14.4,"position_angle_deg":153},{"measured":2020,"magnitude":7.62,"components":"AD","discoverer_code":"SMR   4","separation_arcsec":498.1,"position_angle_deg":103},{"measured":2020,"magnitude":4.01,"components":"AC","discoverer_code":"STF1744","separation_arcsec":715.5,"position_angle_deg":73}],"wikidata_id":"Q66477109","also_known_as":["Zeta Ursae Majoris"],"spectral_type":"A2V","color_index_bv":0.057,"luminosity_solar":77.33925780489973,"variable_mag_max":2.196,"variable_mag_min":2.336,"wikipedia_article":"Mizar","radial_velocity_km_s":-5.6,"surface_temperature_k":9340,"proper_motion_ra_mas_yr":121.23,"proper_motion_dec_mas_yr":-22.01,"stellar_parameters_method":"Spectroscopic determinations compiled from the literature (PASTEL, Soubiran+ 2016)"},"designations":[{"catalog":"Bayer/Flamsteed","designation":"79 Zeta UMa"},{"catalog":"Common name","designation":"Mizar"},{"catalog":"Gliese","designation":"GJ 3783A"},{"catalog":"HD","designation":"HD 116656"},{"catalog":"HIP","designation":"HIP 65378"},{"catalog":"HR","designation":"HR 5054"},{"catalog":"IRAS","designation":"IRAS 13219+5511"}],"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."}