{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.653","julian_year":2026.653,"time":"2026-08-27T16:19:38.975Z","years_from_j2000":26.653,"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":"m13","name":"Hercules Globular Cluster","class":"globular_cluster","category":"cluster","object_type":"Globular cluster","mag":5.8,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":22200,"distance_method":"literature value (curated)","ra_deg":250.42345833333337,"dec_deg":36.46130555555556,"epoch_ra_deg":250.663947,"epoch_dec_deg":36.409349,"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":null,"mass_msun":null,"constellation":"Hercules","discovered":"1714","featured":true,"url":"https://spacecatalog.org/object/m13","radius_km":null,"radius_kind":null,"data_quality":null,"description":"The finest globular cluster in the northern sky: several hundred thousand ancient stars packed into a ball a hundred light-years across, older than the Milky Way's disk.","properties":{"h_mag":3.94,"j_mag":4.45,"k_mag":3.85,"v_mag":5.8,"redshift":-0.000815,"wikidata_id":"Q11312","also_known_as":["Great Globular Cluster in Hercules"],"discovered_by":"Edmond Halley","ngc_type_code":"GCl","major_axis_arcmin":16.5,"wikipedia_article":"Messier 13","distance_reference":"NGC 6205","radial_velocity_km_s":-244},"designations":[{"catalog":"2MASX","designation":"2MASX J16414163+3627407"},{"catalog":"Common name","designation":"Hercules Globular Cluster"},{"catalog":"IAU cluster","designation":"C 1639+365"},{"catalog":"Messier","designation":"M 13"},{"catalog":"MWSC","designation":"MWSC 2445"},{"catalog":"NGC","designation":"NGC 6205"}],"source":{"id":"openngc","name":"OpenNGC","url":"https://github.com/mattiaverga/OpenNGC","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."}