{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.673","julian_year":2026.673,"time":"2026-09-03T23:52:13.058Z","years_from_j2000":26.673,"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":"pgc-4684947","name":"PGC 4684947","class":"galaxy","category":"galaxy","object_type":"Galaxy","mag":15.839,"mag_band":"B","abs_mag":-19.1325599291861,"abs_mag_band":"B","distance_ly":321912514.9675001,"distance_method":"luminosity distance from a photometric redshift (GLADE+), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":258.087189,"dec_deg":-23.269669,"epoch_ra_deg":258.494064,"epoch_dec_deg":-23.302254,"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":"Ophiuchus","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/pgc-4684947","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":15.839,"h_mag":12.337,"j_mag":13.068,"k_mag":12.016,"redshift":0.0225983212992,"redshift_cmb":0.022657,"uncertainties":{"distance_ly":[66356416.52448659,66773085.45313815],"stellar_mass_solar":[6573463514.820507,6573463514.820507]},"stellar_mass_solar":10329728380.432226},"designations":[{"catalog":"2MASX","designation":"2MASX 17122092-2316108"},{"catalog":"Other","designation":"6dFJ1712209-231611"},{"catalog":"PGC","designation":"PGC 4684947"},{"catalog":"WISExSCOS","designation":"WISExSCOS J171220.92-231611"}],"source":{"id":"glade_plus","name":"GLADE+ (Galaxy List for the Advanced Detector Era)","url":"https://cdsarc.cds.unistra.fr/viz-bin/cat/VII/291","license":"VizieR terms; cite Dalya+ 2022 (2022MNRAS.514.1403D)"},"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."}