{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.674","julian_year":2026.674,"time":"2026-09-04T08:02:03.930Z","years_from_j2000":26.674,"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-3539490","name":"PGC 3539490","class":"spiral_galaxy","category":"galaxy","object_type":"Spiral galaxy","mag":16.95,"mag_band":"B","abs_mag":-17.542833422391094,"abs_mag_band":"B","distance_ly":258221595.18524608,"distance_method":"luminosity distance from a photometric redshift (GLADE+), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":163.623,"dec_deg":45.68523,"epoch_ra_deg":164.011907,"epoch_dec_deg":45.542285,"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":"Ursa Major","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/pgc-3539490","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":16.95,"redshift":0.0190346195173,"hubble_type":"3.97","redshift_cmb":0.0182339019193435,"uncertainties":{"distance_ly":[55537678.455222644,55834898.53206132],"stellar_mass_solar":[653907164.5146021,653907164.5146021]},"major_axis_arcmin":0.25767,"minor_axis_arcmin":0.23131,"morphology_source":"SIMBAD (2022MNRAS.513..389R, quality C)","position_angle_deg":124,"stellar_mass_solar":1120983710.5964603},"designations":[{"catalog":"PGC","designation":"PGC 3539490"},{"catalog":"SDSSJ","designation":"SDSSJ 105429.57+454107"},{"catalog":"WISExSCOS","designation":"WISExSCOS J105429.58+454107.2"}],"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."}