{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.675","julian_year":2026.675,"time":"2026-09-04T14:38:34.599Z","years_from_j2000":26.675,"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-4540","name":"NGC 4540","class":"intermediate_spiral_galaxy_sabc","category":"galaxy","object_type":"Intermediate spiral galaxy SABc","mag":12.31,"mag_band":"B","abs_mag":null,"abs_mag_band":null,"distance_ly":73310633.13107207,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":188.7119583333333,"dec_deg":15.551722222222223,"epoch_ra_deg":189.050297,"epoch_dec_deg":15.403648,"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":"Coma Berenices","discovered":"1784","featured":false,"url":"https://spacecatalog.org/object/ngc-4540","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":12.31,"h_mag":9.55,"j_mag":10.24,"k_mag":9.24,"redshift":0.00416,"hubble_type":"SABc","wikidata_id":"Q1112378","redshift_cmb":0.005227473206791844,"discovered_by":"William Herschel","ngc_type_code":"G","uncertainties":{"distance_ly":[14341210.831195954,14341210.831195954]},"major_axis_arcmin":2.19,"minor_axis_arcmin":1.83,"wikipedia_article":"NGC 4540","position_angle_deg":43,"surface_brightness":22.61,"radial_velocity_km_s":1245},"designations":[{"catalog":"2MASX","designation":"2MASX J12345086+1533052"},{"catalog":"IRAS","designation":"IRAS 12323+1549"},{"catalog":"IRAS","designation":"IRAS F12323+1549"},{"catalog":"LEDA","designation":"LEDA 41876"},{"catalog":"MCG","designation":"MCG +03-32-074"},{"catalog":"NGC","designation":"NGC 4540"},{"catalog":"PGC","designation":"PGC 41876"},{"catalog":"SDSS","designation":"SDSS J123450.86+153306.1"},{"catalog":"UGC","designation":"UGC 7742"}],"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."}