{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.686","julian_year":2026.686,"time":"2026-09-08T17:06:20.101Z","years_from_j2000":26.686,"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-4490","name":"NGC 4490","class":"barred_spiral_galaxy_sbcd","category":"galaxy","object_type":"Barred spiral galaxy SBcd","mag":9.72,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":38127219.77439893,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":187.651,"dec_deg":41.64388888888889,"epoch_ra_deg":187.979296,"epoch_dec_deg":41.495364,"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":"1788","featured":false,"url":"https://spacecatalog.org/object/ngc-4490","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":9.76,"h_mag":7.64,"j_mag":8.21,"k_mag":7.35,"v_mag":9.72,"redshift":0.00196,"hubble_type":"SBcd","wikidata_id":"Q1111974","redshift_cmb":0.0027238627885570743,"also_known_as":["Cocoon Galaxy"],"discovered_by":"William Herschel","ngc_type_code":"G","uncertainties":{"distance_ly":[14091135.873273699,14091135.873273699]},"major_axis_arcmin":6.71,"minor_axis_arcmin":1.65,"wikipedia_article":"NGC 4490","position_angle_deg":133,"surface_brightness":21.43,"radial_velocity_km_s":588},"designations":[{"catalog":"2MASX","designation":"2MASX J12303636+4138370"},{"catalog":"IRAS","designation":"IRAS 12281+4155"},{"catalog":"IRAS","designation":"IRAS F12281+4155"},{"catalog":"LEDA","designation":"LEDA 41333"},{"catalog":"MCG","designation":"MCG +07-26-014"},{"catalog":"NGC","designation":"NGC 4490"},{"catalog":"PGC","designation":"PGC 41333"},{"catalog":"UGC","designation":"UGC 7651"}],"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."}