{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.671","julian_year":2026.671,"time":"2026-09-02T22:27:52.086Z","years_from_j2000":26.671,"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":"ngc-4231","name":"NGC 4231","class":"lenticular_galaxy_s0_a","category":"galaxy","object_type":"Lenticular galaxy S0-a","mag":14.65,"mag_band":"B","abs_mag":null,"abs_mag_band":null,"distance_ly":362222739.5558846,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":184.20362500000002,"dec_deg":47.45738888888889,"epoch_ra_deg":184.537764,"epoch_dec_deg":47.308168,"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":"Canes Venatici","discovered":"1788","featured":false,"url":"https://spacecatalog.org/object/ngc-4231","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":14.65,"h_mag":11.33,"j_mag":12.13,"k_mag":11.09,"redshift":0.02474,"hubble_type":"S0-a","wikidata_id":"Q1110044","redshift_cmb":0.02544189141056874,"discovered_by":"William Herschel","ngc_type_code":"G","uncertainties":{"distance_ly":[20394078.016248178,20394078.016248178]},"major_axis_arcmin":0.78,"minor_axis_arcmin":0.63,"position_angle_deg":3,"surface_brightness":22.88,"radial_velocity_km_s":7325},"designations":[{"catalog":"2MASX","designation":"2MASX J12164888+4727268"},{"catalog":"LEDA","designation":"LEDA 39354"},{"catalog":"MCG","designation":"MCG +08-22-094"},{"catalog":"NGC","designation":"NGC 4231"},{"catalog":"PGC","designation":"PGC 39354"},{"catalog":"SDSS","designation":"SDSS J121648.86+472726.5"},{"catalog":"SDSS","designation":"SDSS J121648.86+472726.6"},{"catalog":"SDSS","designation":"SDSS J121648.87+472726.6"},{"catalog":"UGC","designation":"UGC 7304"}],"source":{"id":"openngc","name":"OpenNGC","url":"https://github.com/mattiaverga/OpenNGC","license":"CC-BY-SA-4.0"},"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."}