{"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":"2026-08-27T16:20:17.413Z","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":"ngc-104","name":"47 Tuc Cluster","class":"globular_cluster","category":"cluster","object_type":"Globular cluster","mag":4.09,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":15000,"distance_method":"literature value (curated)","ra_deg":6.022333333333333,"dec_deg":-72.08144444444444,"epoch_ra_deg":6.32387,"epoch_dec_deg":-71.932619,"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":"Tucana","discovered":"1751","featured":true,"url":"https://spacecatalog.org/object/ngc-104","radius_km":null,"radius_kind":null,"data_quality":null,"description":"The second-brightest globular cluster in the sky and one of the densest, with a core so crowded that stars collide and merge into blue stragglers.","properties":{"b_mag":5.78,"h_mag":1.76,"j_mag":2.29,"k_mag":1.54,"v_mag":4.09,"redshift":-0.000057,"wikidata_id":"Q14276","also_known_as":["ksi Tuc","ξ Tuc"],"discovered_by":"Nicolas Louis de Lacaille","ngc_type_code":"GCl","major_axis_arcmin":31.8,"wikipedia_article":"47 Tucanae","distance_reference":"NGC 104","radial_velocity_km_s":-17},"designations":[{"catalog":"2MASX","designation":"2MASX J00240535-7204531"},{"catalog":"Caldwell","designation":"C 106"},{"catalog":"Common name","designation":"47 Tuc Cluster"},{"catalog":"HD","designation":"HD 2051"},{"catalog":"HIP","designation":"HIP 1902"},{"catalog":"HR","designation":"HR 95"},{"catalog":"IAU cluster","designation":"C 0021-723"},{"catalog":"IRAS","designation":"IRAS 00218-7221"},{"catalog":"IRAS","designation":"IRAS F00218-7221"},{"catalog":"MWSC","designation":"MWSC 38"},{"catalog":"NGC","designation":"NGC 104"}],"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."}