{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.679","julian_year":2026.679,"time":"2026-09-06T01:54:53.140Z","years_from_j2000":26.679,"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-3891","name":"NGC 3891","class":"spiral_galaxy_sbc","category":"galaxy","object_type":"Spiral galaxy Sbc","mag":12.76,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":311969139.2921567,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":177.014,"dec_deg":30.359333333333336,"epoch_ra_deg":177.363803,"epoch_dec_deg":30.210077,"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":"Ursa Major","discovered":"1788","featured":false,"url":"https://spacecatalog.org/object/ngc-3891","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":13.44,"h_mag":9.93,"j_mag":10.69,"k_mag":9.75,"v_mag":12.76,"redshift":0.02098,"hubble_type":"Sbc","wikidata_id":"Q1107010","redshift_cmb":0.021968330133026237,"discovered_by":"William Herschel","ngc_type_code":"G","uncertainties":{"distance_ly":[18970919.514841944,18970919.514841944]},"major_axis_arcmin":1.72,"minor_axis_arcmin":1.29,"wikipedia_article":"NGC 3891","position_angle_deg":71,"surface_brightness":23.14,"radial_velocity_km_s":6224},"designations":[{"catalog":"2MASX","designation":"2MASX J11480336+3021335"},{"catalog":"LEDA","designation":"LEDA 36832"},{"catalog":"MCG","designation":"MCG +05-28-031"},{"catalog":"NGC","designation":"NGC 3891"},{"catalog":"PGC","designation":"PGC 36832"},{"catalog":"SDSS","designation":"SDSS J114803.35+302133.5"},{"catalog":"SDSS","designation":"SDSS J114803.35+302133.6"},{"catalog":"UGC","designation":"UGC 6772"}],"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."}