{"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":"2026-09-03T11:51:45.013Z","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-4870","name":"NGC 4870","class":"spiral_galaxy_sbc","category":"galaxy","object_type":"Spiral galaxy Sbc","mag":15.54,"mag_band":"B","abs_mag":null,"abs_mag_band":null,"distance_ly":518704212.55579656,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":194.82404166666663,"dec_deg":37.048361111111106,"epoch_ra_deg":195.140665,"epoch_dec_deg":36.903359,"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":"1878","featured":false,"url":"https://spacecatalog.org/object/ngc-4870","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":15.54,"h_mag":11.82,"j_mag":12.45,"k_mag":11.42,"redshift":0.03534,"hubble_type":"Sbc","wikidata_id":"Q1115118","redshift_cmb":0.03614949706634074,"discovered_by":"Lawrence Parsons, 4th Earl of Rosse","ngc_type_code":"G","uncertainties":{"distance_ly":[25354158.027376033,25354158.027376033]},"major_axis_arcmin":0.91,"minor_axis_arcmin":0.31,"position_angle_deg":2,"surface_brightness":23.29,"radial_velocity_km_s":10408},"designations":[{"catalog":"2MASX","designation":"2MASX J12591779+3702540"},{"catalog":"LEDA","designation":"LEDA 44569"},{"catalog":"NGC","designation":"NGC 4870"},{"catalog":"PGC","designation":"PGC 44569"},{"catalog":"SDSS","designation":"SDSS J125917.76+370254.0"},{"catalog":"SDSS","designation":"SDSS J125917.77+370254.1"}],"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."}