{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.671","julian_year":2026.671,"time":"2026-09-02T23:45:48.502Z","years_from_j2000":26.671,"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-998","name":"NGC 998","class":"galaxy","category":"galaxy","object_type":"Galaxy","mag":14.6,"mag_band":"B","abs_mag":null,"abs_mag_band":null,"distance_ly":298665924.72370034,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":39.318749999999994,"dec_deg":7.335805555555555,"epoch_ra_deg":39.674887,"epoch_dec_deg":7.452617,"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":"Cetus","discovered":"1863","featured":false,"url":"https://spacecatalog.org/object/ngc-998","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":14.6,"h_mag":11.42,"j_mag":12.15,"k_mag":11.07,"redshift":0.02184,"wikidata_id":"Q1040815","redshift_cmb":0.02104588944268282,"discovered_by":"Albert Marth","ngc_type_code":"G","uncertainties":{"distance_ly":[18612810.652834047,18612810.652834047]},"major_axis_arcmin":0.63,"minor_axis_arcmin":0.52,"wikipedia_article":"NGC 998","position_angle_deg":175,"radial_velocity_km_s":6476},"designations":[{"catalog":"2MASX","designation":"2MASX J02371649+0720091"},{"catalog":"LEDA","designation":"LEDA 9934"},{"catalog":"NGC","designation":"NGC 998"},{"catalog":"PGC","designation":"PGC 9934"}],"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."}