{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.678","julian_year":2026.678,"time":"2026-09-05T13:22:08.596Z","years_from_j2000":26.678,"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-3996839","name":"PGC 3996839","class":"galaxy","category":"galaxy","object_type":"Galaxy","mag":18.1,"mag_band":"B","abs_mag":-15.738964288543094,"abs_mag_band":"B","distance_ly":191081540.06382406,"distance_method":"luminosity distance from a photometric redshift (GLADE+), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":130.658,"dec_deg":45.39499,"epoch_ra_deg":131.118097,"epoch_dec_deg":45.298836,"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":"Lynx","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/pgc-3996839","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":18.1,"redshift":0.013577976789,"redshift_cmb":0.0135402165225657,"uncertainties":{"distance_ly":[39458687.05122831,39610403.24745564],"stellar_mass_solar":[84076261.79343389,84076261.79343389]},"stellar_mass_solar":140127102.9890565},"designations":[{"catalog":"PGC","designation":"PGC 3996839"},{"catalog":"SDSSJ","designation":"SDSSJ 084237.93+452341.7"},{"catalog":"WISExSCOS","designation":"WISExSCOS J084237.98+452341.7"}],"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."}