{"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":"2026-09-03T10:43:47.812Z","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-891","name":"NGC 891","class":"spiral_galaxy_sb","category":"galaxy","object_type":"Spiral galaxy Sb","mag":10.01,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":null,"distance_method":null,"ra_deg":35.639208333333336,"dec_deg":42.34913888888889,"epoch_ra_deg":36.06153,"epoch_dec_deg":42.471652,"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":"Andromeda","discovered":"1784","featured":false,"url":"https://spacecatalog.org/object/ngc-891","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":10.84,"h_mag":6.36,"j_mag":7.26,"k_mag":5.94,"v_mag":10.01,"redshift":0.001763,"hubble_type":"Sb","wikidata_id":"Q490345","redshift_cmb":0.0010521707279411707,"also_known_as":["Outer Limits Galaxy","Silver Sliver Galaxy"],"discovered_by":"William Herschel","ngc_type_code":"G","major_axis_arcmin":13.03,"minor_axis_arcmin":3.03,"wikipedia_article":"NGC 891","position_angle_deg":22,"surface_brightness":24.17,"radial_velocity_km_s":528},"designations":[{"catalog":"2MASX","designation":"2MASX J02223290+4220539"},{"catalog":"Caldwell","designation":"C 23"},{"catalog":"IRAS","designation":"IRAS 02193+4207"},{"catalog":"IRAS","designation":"IRAS F02194+4207"},{"catalog":"LEDA","designation":"LEDA 9031"},{"catalog":"MCG","designation":"MCG +07-05-046"},{"catalog":"NGC","designation":"NGC 891"},{"catalog":"PGC","designation":"PGC 9031"},{"catalog":"UGC","designation":"UGC 1831"}],"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."}