{"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":"2026-09-03T15:14:34.120Z","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-1640184","name":"PGC 1640184","class":"galaxy","category":"galaxy","object_type":"Galaxy","mag":16.63,"mag_band":"B","abs_mag":-17.830357880751986,"abs_mag_band":"B","distance_ly":254388486.43945885,"distance_method":"luminosity distance from a photometric redshift (GLADE+), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":238.378418,"dec_deg":20.983589,"epoch_ra_deg":238.674134,"epoch_dec_deg":20.90358,"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-1640184","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":16.63,"h_mag":14.342,"j_mag":14.995,"k_mag":14.214,"redshift":0.0183981091991,"redshift_cmb":0.0179667989992995,"uncertainties":{"distance_ly":[53729019.67109565,54006445.67112714],"stellar_mass_solar":[560492807.4412234,560492807.4412234]},"stellar_mass_solar":934154679.0687057},"designations":[{"catalog":"2MASX","designation":"2MASX 15533082+2059009"},{"catalog":"PGC","designation":"PGC 1640184"},{"catalog":"WISExSCOS","designation":"WISExSCOS J155330.77+205901.6"}],"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."}