{"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":"2026-09-03T12:25:12.639Z","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-818","name":"NGC 818","class":"spiral_galaxy_sbc","category":"galaxy","object_type":"Spiral galaxy Sbc","mag":12.51,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":188622715.32398963,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":32.185500000000005,"dec_deg":38.77719444444444,"epoch_ra_deg":32.592467,"epoch_dec_deg":38.904659,"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":"Andromeda","discovered":"1786","featured":false,"url":"https://spacecatalog.org/object/ngc-818","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":13.18,"h_mag":9.83,"j_mag":10.37,"k_mag":9.42,"v_mag":12.51,"redshift":0.014156,"hubble_type":"Sbc","wikidata_id":"Q1039436","redshift_cmb":0.013367707387952787,"discovered_by":"William Herschel","ngc_type_code":"G","uncertainties":{"distance_ly":[16034926.01027478,16034926.01027478]},"major_axis_arcmin":2.2,"minor_axis_arcmin":0.76,"wikipedia_article":"NGC 818","position_angle_deg":112,"surface_brightness":22.8,"radial_velocity_km_s":4214},"designations":[{"catalog":"2MASX","designation":"2MASX J02084451+3846381"},{"catalog":"IRAS","designation":"IRAS 02057+3832"},{"catalog":"IRAS","designation":"IRAS F02057+3832"},{"catalog":"LEDA","designation":"LEDA 8185"},{"catalog":"MCG","designation":"MCG +06-05-086"},{"catalog":"NGC","designation":"NGC 818"},{"catalog":"PGC","designation":"PGC 8185"},{"catalog":"UGC","designation":"UGC 1633"}],"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."}