{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.675","julian_year":2026.675,"time":"2026-09-04T10:25:18.555Z","years_from_j2000":26.675,"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-4491567","name":"PGC 4491567","class":"galaxy","category":"galaxy","object_type":"Galaxy","mag":18.2,"mag_band":"B","abs_mag":-16.183578564266856,"abs_mag_band":"B","distance_ly":245550932.68225232,"distance_method":"luminosity distance from a photometric redshift (GLADE+), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":242.667,"dec_deg":4.90254,"epoch_ra_deg":242.999857,"epoch_dec_deg":4.83224,"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":"Serpens","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/pgc-4491567","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":18.2,"redshift":0.0183981091991,"redshift_cmb":0.017350574262984,"uncertainties":{"distance_ly":[53567451.73751162,53845653.334317215],"stellar_mass_solar":[186831656.7929872,186831656.7929872]},"stellar_mass_solar":280247485.18948084},"designations":[{"catalog":"PGC","designation":"PGC 4491567"},{"catalog":"SDSSJ","designation":"SDSSJ 161040.16+045408.8"},{"catalog":"WISExSCOS","designation":"WISExSCOS J161040.20+045409.4"}],"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."}