{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.687","julian_year":2026.687,"time":"2026-09-08T23:20:09.548Z","years_from_j2000":26.687,"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":"gw170817-remnant","name":"GW170817 remnant","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":130000000,"distance_method":null,"ra_deg":197.44871,"dec_deg":-23.38398,"epoch_ra_deg":197.81172,"epoch_dec_deg":-23.527259,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":5.368706650884737e+30,"mass_msun":2.7,"constellation":"Hydra","discovered":"2017","featured":true,"url":"https://spacecatalog.org/object/gw170817-remnant","radius_km":null,"radius_kind":null,"data_quality":null,"description":"Probably the lightest black hole known, and the only one whose birth was both heard and seen: two neutron stars merged, gravitational waves arrived first, and telescopes caught the afterglow that forged heavy elements.","properties":{"accretion":"none","mass_solar":2.7},"designations":[{"catalog":"Gravitational wave event","designation":"GW170817"}],"source":{"id":"curated","name":"SpaceCatalog curated data","url":"https://spacecatalog.org/releases","license":"CC-BY-4.0"},"updated_at":"2026-09-02T19:50:56.720Z","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."}