{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.778","julian_year":2026.778,"time":"2026-10-11T23:42:51.057Z","years_from_j2000":26.778,"frame":"date","applied":"Proper motion, then precession and nutation. The catalogued position is carried along the great circle the object's own published motion puts it on, at a constant velocity, from the epoch that position was measured at, 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. The motion runs from position_epoch_jyear where the upstream publishes one — a timed pulsar's position belongs to the year it was timed — and from J2000 where it does not. 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":"cyg-x1","name":"Cygnus X-1","class":"stellar_mass_black_hole","category":"black_hole","object_type":"Stellar-mass black hole","mag":null,"mag_band":null,"abs_mag":null,"abs_mag_band":null,"distance_ly":7240,"distance_method":null,"ra_deg":299.59032,"dec_deg":35.2016,"epoch_ra_deg":299.84264,"epoch_dec_deg":35.273961,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"position_epoch_jyear":null,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":4.215428925879868e+31,"mass_msun":21.2,"constellation":"Cygnus","discovered":"1964","featured":true,"url":"https://spacecatalog.org/object/cyg-x1","source":{"id":"curated","name":"SpaceCatalog curated data","url":"https://spacecatalog.org/releases","license":"CC-BY-4.0","attribution":null,"commercial_use":"allowed"},"radius_km":null,"radius_kind":null,"data_quality":null,"description":"The first widely accepted black hole, and the subject of a famous bet between Stephen Hawking and Kip Thorne. It strips gas from a blue supergiant companion, blazing in X-rays.","properties":{"accretion":"persistent","mass_solar":21.2,"disc_inclination_deg":27.5},"designations":[{"catalog":"Common name","designation":"Cygnus X-1"},{"catalog":"Common name","designation":"Cyg X-1"}],"updated_at":"2026-10-01T09:42:28.932Z","attribution":"Data from SpaceCatalog.org. Each record names its upstream in `source`, with that producer's terms in `source.license`, the acknowledgement it asks for in `source.attribution`, and whether its terms allow commercial use in `source.commercial_use`; those terms govern the record, and citing SpaceCatalog does not discharge them."}