{"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":"2026-09-01T13:16:47.634Z","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":"capella","name":"Capella","class":"g3iii_yellow_giant","category":"star","object_type":"G3III: yellow giant","mag":0.08,"mag_band":"V","abs_mag":-0.51,"abs_mag_band":"V","distance_ly":42.80280607327911,"distance_method":"parallax","ra_deg":79.17225,"dec_deg":45.997991,"epoch_ra_deg":79.668793,"epoch_dec_deg":46.024543,"epoch_moved_arcsec":11.567,"pm_ra_mas_yr":75.52,"pm_dec_mas_yr":-427.13,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Auriga","discovered":"Antiquity","featured":true,"url":"https://spacecatalog.org/object/capella","radius_km":null,"radius_kind":null,"data_quality":null,"description":"A single bright point that is really four stars: two yellow giants orbiting each other closely, plus a distant pair of red dwarfs.","properties":{"wds_id":"05167+4600","companions":[{"measured":2013,"magnitude":13.6,"components":"AD","discoverer_code":"BU 1392","separation_arcsec":71.5,"position_angle_deg":194},{"measured":2013,"magnitude":17.1,"components":"AB","discoverer_code":"BAR  25","separation_arcsec":91.5,"position_angle_deg":6},{"measured":2012,"magnitude":13,"components":"AQ","discoverer_code":"SMR  26","separation_arcsec":91.9,"position_angle_deg":216},{"measured":2022,"magnitude":10.21,"components":"AF","discoverer_code":"HJ 2256","separation_arcsec":104.7,"position_angle_deg":134},{"measured":2013,"magnitude":15.1,"components":"AC","discoverer_code":"BU 1392","separation_arcsec":132.3,"position_angle_deg":332},{"measured":2013,"magnitude":13,"components":"AI","discoverer_code":"SMR  26","separation_arcsec":132.9,"position_angle_deg":273},{"measured":2012,"magnitude":13,"components":"AR","discoverer_code":"SMR  26","separation_arcsec":133.7,"position_angle_deg":264},{"measured":2013,"magnitude":12.1,"components":"AE","discoverer_code":"BU 1392","separation_arcsec":192.9,"position_angle_deg":326},{"measured":2003,"magnitude":8.1,"components":"AG","discoverer_code":"SHJ  51","separation_arcsec":522.4,"position_angle_deg":349},{"measured":2014,"magnitude":9.99,"components":"AH","discoverer_code":"FRH   1","separation_arcsec":722.8,"position_angle_deg":142}],"wikidata_id":"Q12970","also_known_as":["Alhajoth","Alpha Aurigae","alf Aur","α Aur","α Aurigae"],"spectral_type":"G3III:","uncertainties":{"metallicity_fe_h":[0.06,0.06]},"color_index_bv":0.795,"luminosity_solar":139.3156802945302,"metallicity_fe_h":-0.43,"wikipedia_article":"Capella","radial_velocity_km_s":22.2,"spectral_type_source":"SIMBAD (1989ApJS...71..245K, quality C)","surface_gravity_log_g":2.51,"surface_temperature_k":5155,"metallicity_fe_h_source":"Median of 2 spectroscopic determinations in 3 papers, compiled from the literature (PASTEL, Soubiran+ 2016); the error bar is the scatter between them","proper_motion_ra_mas_yr":75.52,"proper_motion_dec_mas_yr":-427.13,"stellar_parameters_method":"Spectroscopic determinations compiled from the literature (PASTEL, Soubiran+ 2016)"},"designations":[{"catalog":"Bayer/Flamsteed","designation":"13 Alpha Aur"},{"catalog":"Common name","designation":"Capella"},{"catalog":"Gliese","designation":"GJ 194"},{"catalog":"Gliese","designation":"GJ 194 A"},{"catalog":"Gliese","designation":"GJ 194 B"},{"catalog":"Gliese","designation":"Gl 194A"},{"catalog":"HD","designation":"HD 34029"},{"catalog":"HIP","designation":"HIP 24608"},{"catalog":"HR","designation":"HR 1708"},{"catalog":"IRAS","designation":"IRAS 05130+4556"}],"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."}