{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.672","julian_year":2026.672,"time":"2026-09-03T08:32:06.919Z","years_from_j2000":26.672,"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-3983","name":"NGC 3983","class":"lenticular_galaxy_s0_a","category":"galaxy","object_type":"Lenticular galaxy S0-a","mag":14.62,"mag_band":"B","abs_mag":null,"abs_mag_band":null,"distance_ly":213097248.1836357,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":179.09866666666667,"dec_deg":23.867944444444444,"epoch_ra_deg":179.444561,"epoch_dec_deg":23.718498,"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":"Leo","discovered":"1785","featured":false,"url":"https://spacecatalog.org/object/ngc-3983","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":14.62,"h_mag":10.46,"j_mag":11.15,"k_mag":10.17,"redshift":0.01403,"hubble_type":"S0-a","wikidata_id":"Q1108405","redshift_cmb":0.015082871453613977,"discovered_by":"William Herschel","ngc_type_code":"G","uncertainties":{"distance_ly":[16540474.054236574,16540474.054236574]},"major_axis_arcmin":1.17,"minor_axis_arcmin":0.27,"position_angle_deg":113,"surface_brightness":23.29,"radial_velocity_km_s":4177},"designations":[{"catalog":"2MASX","designation":"2MASX J11562369+2352049"},{"catalog":"IRAS","designation":"IRAS F11538+2408"},{"catalog":"LEDA","designation":"LEDA 37514"},{"catalog":"MCG","designation":"MCG +04-28-098"},{"catalog":"NGC","designation":"NGC 3983"},{"catalog":"PGC","designation":"PGC 37514"},{"catalog":"SDSS","designation":"SDSS J115623.67+235204.6"},{"catalog":"SDSS","designation":"SDSS J115623.68+235204.6"},{"catalog":"UGC","designation":"UGC 6914"}],"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."}