{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.668","julian_year":2026.668,"time":"2026-09-01T23:42:53.309Z","years_from_j2000":26.668,"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-3901","name":"NGC 3901","class":"spiral_galaxy_sc","category":"galaxy","object_type":"Spiral galaxy Sc","mag":14.52,"mag_band":"B","abs_mag":null,"abs_mag_band":null,"distance_ly":81112681.94773728,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":175.70716666666667,"dec_deg":77.37269444444443,"epoch_ra_deg":176.108709,"epoch_dec_deg":77.223774,"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":"Camelopardalis","discovered":"1801","featured":false,"url":"https://spacecatalog.org/object/ngc-3901","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":14.52,"h_mag":12.08,"j_mag":12.53,"k_mag":11.6,"redshift":0.005661,"hubble_type":"Sc","wikidata_id":"Q1107050","redshift_cmb":0.005781379067055781,"discovered_by":"William Herschel","ngc_type_code":"G","uncertainties":{"distance_ly":[14414956.11668421,14414956.11668421]},"major_axis_arcmin":1.37,"minor_axis_arcmin":0.67,"position_angle_deg":166,"surface_brightness":23.38,"radial_velocity_km_s":1692},"designations":[{"catalog":"2MASX","designation":"2MASX J11424981+7722212"},{"catalog":"IRAS","designation":"IRAS F11399+7738"},{"catalog":"LEDA","designation":"LEDA 36386"},{"catalog":"MCG","designation":"MCG +13-09-001"},{"catalog":"NGC","designation":"NGC 3901"},{"catalog":"PGC","designation":"PGC 36386"},{"catalog":"UGC","designation":"UGC 6675"}],"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."}