{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.670","julian_year":2026.67,"time":"2026-09-02T19:22:43.331Z","years_from_j2000":26.67,"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":"sirius","name":"Sirius","class":"a0ma1va_white_main_sequence_star","category":"star","object_type":"A0mA1Va white main-sequence star","mag":-1.44,"mag_band":"V","abs_mag":1.454,"abs_mag_band":"V","distance_ly":8.601069836768241,"distance_method":"parallax","ra_deg":101.287215,"dec_deg":-16.716116,"epoch_ra_deg":101.582812,"epoch_dec_deg":-16.75255,"epoch_moved_arcsec":35.723,"pm_ra_mas_yr":-546.01,"pm_dec_mas_yr":-1223.08,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Canis Major","discovered":"Antiquity","featured":true,"url":"https://spacecatalog.org/object/sirius","radius_km":null,"radius_kind":null,"data_quality":null,"description":"The brightest star in the night sky, orbited by a white dwarf companion — the burned-out core of a star that died 120 million years ago.","properties":{"wds_id":"06451-1643","companions":[{"measured":2024,"magnitude":8.44,"components":"AB","discoverer_code":"AGC   1","separation_arcsec":11.1,"position_angle_deg":59},{"measured":1915,"magnitude":14,"components":"AD","discoverer_code":"AGC   1","separation_arcsec":31.6,"position_angle_deg":183},{"measured":1999,"magnitude":12.6,"components":"AC","discoverer_code":"LEC   1","separation_arcsec":64.5,"position_angle_deg":30},{"measured":2011,"magnitude":13.8,"components":"AF","discoverer_code":"BU 1411","separation_arcsec":125.7,"position_angle_deg":61},{"measured":2011,"magnitude":14.5,"components":"AE","discoverer_code":"HL    3","separation_arcsec":188.3,"position_angle_deg":47}],"wikidata_id":"Q3409","also_known_as":["Alpha Canis Majoris","α CMa","α Canis Majoris"],"spectral_type":"A0mA1Va","uncertainties":{"metallicity_fe_h":[0.335,0.335]},"color_index_bv":0.009,"luminosity_solar":22.824433121735034,"metallicity_fe_h":0.49,"variable_mag_max":-1.523,"variable_mag_min":-1.333,"wikipedia_article":"Sirius","radial_velocity_km_s":-9.4,"spectral_type_source":"SIMBAD (2003AJ....126.2048G, quality C)","surface_gravity_log_g":4.3,"surface_temperature_k":9847,"metallicity_fe_h_source":"Median of 17 spectroscopic determinations in 17 papers, compiled from the literature (PASTEL, Soubiran+ 2016); the error bar is the scatter between them","proper_motion_ra_mas_yr":-546.01,"proper_motion_dec_mas_yr":-1223.08,"stellar_parameters_method":"Spectroscopic determinations compiled from the literature (PASTEL, Soubiran+ 2016)"},"designations":[{"catalog":"Bayer/Flamsteed","designation":"9 Alpha CMa"},{"catalog":"Common name","designation":"Sirius"},{"catalog":"Gliese","designation":"GJ 244 A"},{"catalog":"Gliese","designation":"Gl 244A"},{"catalog":"HD","designation":"HD 48915"},{"catalog":"HD","designation":"HD 48915A"},{"catalog":"HIP","designation":"HIP 32349"},{"catalog":"HR","designation":"HR 2491"}],"source":{"id":"hyg","name":"HYG Database v4.1","url":"https://github.com/astronexus/HYG-Database","license":"CC-BY-SA-4.0"},"updated_at":"2026-09-02T18:38:07.546Z","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."}