{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.654","julian_year":2026.654,"time":"2026-08-27T17:05:39.359Z","years_from_j2000":26.654,"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":"arcturus","name":"Arcturus","class":"k1_5iiife_0_5_orange_giant","category":"star","object_type":"K1.5IIIFe-0.5 orange giant","mag":-0.05,"mag_band":"V","abs_mag":-0.307,"abs_mag_band":"V","distance_ly":36.71705422146239,"distance_method":"parallax","ra_deg":213.91545,"dec_deg":19.18241,"epoch_ra_deg":214.222491,"epoch_dec_deg":19.042512,"epoch_moved_arcsec":60.74,"pm_ra_mas_yr":-1093.45,"pm_dec_mas_yr":-1999.4,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Boötes","discovered":"Antiquity","featured":true,"url":"https://spacecatalog.org/object/arcturus","radius_km":null,"radius_kind":null,"data_quality":null,"description":"An orange giant racing through the galaxy at an angle to the disk, probably born in a satellite galaxy the Milky Way absorbed.","properties":{"wikidata_id":"Q12985","spectral_type":"K1.5IIIFe-0.5","color_index_bv":1.239,"luminosity_solar":115.55799554021293,"wikipedia_article":"Arcturus","radial_velocity_km_s":-5,"spectral_type_source":"SIMBAD (1989ApJS...71..245K, quality B)","proper_motion_ra_mas_yr":-1093.45,"proper_motion_dec_mas_yr":-1999.4},"designations":[{"catalog":"Bayer/Flamsteed","designation":"16 Alpha Boo"},{"catalog":"Common name","designation":"Arcturus"},{"catalog":"Gliese","designation":"GJ 541"},{"catalog":"Gliese","designation":"Gl 541"},{"catalog":"HD","designation":"HD 124897"},{"catalog":"HIP","designation":"HIP 69673"},{"catalog":"HR","designation":"HR 5340"},{"catalog":"IRAS","designation":"IRAS 14133+1925"}],"source":{"id":"hyg","name":"HYG Database v4.1","url":"https://github.com/astronexus/HYG-Database","license":"CC-BY-SA-4.0"},"updated_at":"2026-08-27T16:03:54.983Z","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."}