{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.681","julian_year":2026.681,"time":"2026-09-06T16:36:10.988Z","years_from_j2000":26.681,"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-6684a","name":"NGC 6684A","class":"irregular_galaxy_ib","category":"galaxy","object_type":"Irregular galaxy IB","mag":13.22,"mag_band":"B","abs_mag":null,"abs_mag_band":null,"distance_ly":45851779.855120316,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":283.09504166666665,"dec_deg":-64.83147222222222,"epoch_ra_deg":283.749759,"epoch_dec_deg":-64.798985,"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":"Pavo","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/ngc-6684a","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":13.22,"redshift":0.003361,"hubble_type":"IB","wikidata_id":"Q1147077","redshift_cmb":0.0032743460085757903,"discovered_by":"John Frederick William Herschel","ngc_type_code":"G","uncertainties":{"distance_ly":[14134255.159546563,14134255.159546563]},"major_axis_arcmin":1.95,"minor_axis_arcmin":1.34,"position_angle_deg":140,"surface_brightness":23.26,"radial_velocity_km_s":1006},"designations":[{"catalog":"ESO","designation":"ESO 104-019"},{"catalog":"ESO","designation":"ESO 104-19"},{"catalog":"ESO-LV","designation":"ESO-LV 104-0190"},{"catalog":"LEDA","designation":"LEDA 62517"},{"catalog":"NGC","designation":"NGC 6684A"},{"catalog":"PGC","designation":"PGC 62517"}],"source":{"id":"openngc","name":"OpenNGC","url":"https://github.com/mattiaverga/OpenNGC","license":"CC-BY-SA-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."}