{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.670","julian_year":2026.67,"time":"2026-09-02T15:57:02.328Z","years_from_j2000":26.67,"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-4151","name":"NGC 4151","class":"spiral_galaxy_sab","category":"galaxy","object_type":"Spiral galaxy Sab","mag":11.48,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":57241920.07503844,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":182.63575,"dec_deg":39.405722222222224,"epoch_ra_deg":182.975657,"epoch_dec_deg":39.256313,"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":"1787","featured":false,"url":"https://spacecatalog.org/object/ngc-4151","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":11.36,"h_mag":7.79,"j_mag":8.5,"k_mag":7.38,"v_mag":11.48,"redshift":0.003262,"hubble_type":"Sab","wikidata_id":"Q942187","redshift_cmb":0.004085217332550517,"also_known_as":["Eye of Sauron"],"discovered_by":"William Herschel","ngc_type_code":"G","uncertainties":{"distance_ly":[14210026.883335358,14210026.883335358]},"major_axis_arcmin":2.88,"minor_axis_arcmin":2.21,"wikipedia_article":"NGC 4151","position_angle_deg":50,"surface_brightness":22.23,"radial_velocity_km_s":976},"designations":[{"catalog":"2MASX","designation":"2MASX J12103265+3924207"},{"catalog":"IRAS","designation":"IRAS S12079+3941"},{"catalog":"IRAS","designation":"IRAS S12080+3940"},{"catalog":"IRAS","designation":"IRAS Z12080+3940"},{"catalog":"LEDA","designation":"LEDA 38739"},{"catalog":"MCG","designation":"MCG +07-25-044"},{"catalog":"NGC","designation":"NGC 4151"},{"catalog":"PGC","designation":"PGC 38739"},{"catalog":"SDSS","designation":"SDSS J121032.57+392421.1"},{"catalog":"TYC","designation":"TYC 3017-939-1"},{"catalog":"UGC","designation":"UGC 7166"}],"source":{"id":"openngc","name":"OpenNGC","url":"https://github.com/mattiaverga/OpenNGC","license":"CC-BY-SA-4.0"},"updated_at":"2026-09-01T22:58:55.274Z","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."}