{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.666","julian_year":2026.666,"time":"2026-09-01T02:33:11.644Z","years_from_j2000":26.666,"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-643b","name":"NGC 643B","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":188173816.35478327,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":24.803041666666665,"dec_deg":-75.0111111111111,"epoch_ra_deg":24.921259,"epoch_dec_deg":-74.874529,"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":"Hydrus","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/ngc-643b","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":14.62,"h_mag":10.49,"j_mag":11.3,"k_mag":10.1,"redshift":0.013447,"hubble_type":"S0-a","wikidata_id":"Q1037875","redshift_cmb":0.013336208266075067,"discovered_by":"John Frederick William Herschel","ngc_type_code":"G","uncertainties":{"distance_ly":[16026070.711492447,16026070.711492447]},"major_axis_arcmin":1.75,"minor_axis_arcmin":0.47,"position_angle_deg":116,"surface_brightness":24.39,"radial_velocity_km_s":4004},"designations":[{"catalog":"2MASX","designation":"2MASX J01391285-7500392"},{"catalog":"ESO","designation":"ESO 029-053"},{"catalog":"ESO","designation":"ESO 29-53"},{"catalog":"ESO-LV","designation":"ESO-LV 29-0530"},{"catalog":"IRAS","designation":"IRAS 01384-7515"},{"catalog":"IRAS","designation":"IRAS F01384-7515"},{"catalog":"LEDA","designation":"LEDA 6117"},{"catalog":"NGC","designation":"NGC 643B"},{"catalog":"PGC","designation":"PGC 6117"},{"catalog":"TYC","designation":"TYC 9348-1106-1"}],"source":{"id":"openngc","name":"OpenNGC","url":"https://github.com/mattiaverga/OpenNGC","license":"CC-BY-SA-4.0"},"updated_at":"2026-08-30T09:56:50.739Z","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."}