{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.676","julian_year":2026.676,"time":"2026-09-04T19:32:01.162Z","years_from_j2000":26.676,"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-4993","name":"NGC 4993","class":"elliptical_galaxy_e_s0","category":"galaxy","object_type":"Elliptical galaxy E-S0","mag":13.45,"mag_band":"B","abs_mag":null,"abs_mag_band":null,"distance_ly":152588616.72249866,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":197.44875,"dec_deg":-23.383888888888887,"epoch_ra_deg":197.811567,"epoch_dec_deg":-23.527078,"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":"Hydra","discovered":"1789","featured":false,"url":"https://spacecatalog.org/object/ngc-4993","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":13.45,"h_mag":9.51,"j_mag":10.18,"k_mag":9.22,"redshift":0.009787,"hubble_type":"E-S0","wikidata_id":"Q1116212","redshift_cmb":0.010834527307539421,"discovered_by":"John Frederick William Herschel, William Herschel","ngc_type_code":"G","uncertainties":{"distance_ly":[15375580.414741814,15375580.414741814]},"major_axis_arcmin":1.55,"minor_axis_arcmin":1.35,"wikipedia_article":"NGC 4993","position_angle_deg":173,"surface_brightness":23.16,"radial_velocity_km_s":2920},"designations":[{"catalog":"2MASX","designation":"2MASX J13094770-2323017"},{"catalog":"ESO","designation":"ESO 508-018"},{"catalog":"ESO","designation":"ESO 508-18"},{"catalog":"ESO-LV","designation":"ESO-LV 508-0180"},{"catalog":"LEDA","designation":"LEDA 45657"},{"catalog":"MCG","designation":"MCG -04-31-039"},{"catalog":"NGC","designation":"NGC 4993"},{"catalog":"NGC","designation":"NGC 4994"},{"catalog":"PGC","designation":"PGC 45657"}],"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."}