{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.686","julian_year":2026.686,"time":"2026-09-08T09:12:38.811Z","years_from_j2000":26.686,"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-3994957","name":"PGC 3994957","class":"galaxy","category":"galaxy","object_type":"Galaxy","mag":16.58,"mag_band":"B","abs_mag":-17.332399527917964,"abs_mag_band":"B","distance_ly":197654078.75324512,"distance_method":"luminosity distance from a photometric redshift (GLADE+), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":226.463,"dec_deg":51.25237,"epoch_ra_deg":226.674152,"epoch_dec_deg":51.147847,"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":"Boötes","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/pgc-3994957","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":16.58,"redshift":0.0130823765412,"redshift_cmb":0.0140011253100503,"uncertainties":{"distance_ly":[38226502.33676118,38366613.93226987]}},"designations":[{"catalog":"PGC","designation":"PGC 3994957"},{"catalog":"SDSSJ","designation":"SDSSJ 150550.99+511508.1"}],"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."}