{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.667","julian_year":2026.667,"time":"2026-09-01T13:55:47.210Z","years_from_j2000":26.667,"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":"m28","name":"M28","class":"globular_cluster","category":"cluster","object_type":"Globular cluster","mag":6.9,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":18590.913529854373,"distance_method":"Globular-cluster distance scale (Harris 2010)","ra_deg":276.1370416666666,"dec_deg":-24.869833333333332,"epoch_ra_deg":276.549982,"epoch_dec_deg":-24.85562,"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":"Sagittarius","discovered":"1764","featured":false,"url":"https://spacecatalog.org/object/m28","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"v_mag":6.9,"redshift":0.000037,"wikidata_id":"Q13644","discovered_by":"Charles Messier","ngc_type_code":"GCl","major_axis_arcmin":5.1,"wikipedia_article":"Messier 28","distance_reference":"NGC 6626","radial_velocity_km_s":11},"designations":[{"catalog":"HD","designation":"HD 169199"},{"catalog":"IAU cluster","designation":"C 1821-249"},{"catalog":"Messier","designation":"M 28"},{"catalog":"MWSC","designation":"MWSC 2908"},{"catalog":"NGC","designation":"NGC 6626"}],"source":{"id":"openngc","name":"OpenNGC","url":"https://github.com/mattiaverga/OpenNGC","license":"CC-BY-SA-4.0"},"updated_at":"2026-08-30T09:56:50.739Z","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."}