{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.681","julian_year":2026.681,"time":"2026-09-06T13:18:31.212Z","years_from_j2000":26.681,"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-4956","name":"NGC 4956","class":"lenticular_galaxy_s0","category":"galaxy","object_type":"Lenticular galaxy S0","mag":12.38,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":236069979.92721388,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":196.25391666666667,"dec_deg":35.17802777777778,"epoch_ra_deg":196.569967,"epoch_dec_deg":35.033914,"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":"1785","featured":false,"url":"https://spacecatalog.org/object/ngc-4956","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":13.27,"h_mag":9.82,"j_mag":10.5,"k_mag":9.6,"v_mag":12.38,"redshift":0.015881,"hubble_type":"S0","wikidata_id":"Q1115927","redshift_cmb":0.0166888698272587,"discovered_by":"William Herschel","ngc_type_code":"G","uncertainties":{"distance_ly":[17053240.23966576,17053240.23966576]},"major_axis_arcmin":1.56,"minor_axis_arcmin":1.52,"position_angle_deg":60,"surface_brightness":22.99,"radial_velocity_km_s":4723},"designations":[{"catalog":"2MASX","designation":"2MASX J13050097+3510413"},{"catalog":"LEDA","designation":"LEDA 45236"},{"catalog":"MCG","designation":"MCG +06-29-025"},{"catalog":"NGC","designation":"NGC 4956"},{"catalog":"PGC","designation":"PGC 45236"},{"catalog":"SDSS","designation":"SDSS J130500.94+351040.9"},{"catalog":"UGC","designation":"UGC 8177"}],"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."}