{"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":"2026-09-03T14:43:09.874Z","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-4531","name":"NGC 4531","class":"lenticular_galaxy_s0_a","category":"galaxy","object_type":"Lenticular galaxy S0-a","mag":12.36,"mag_band":"B","abs_mag":null,"abs_mag_band":null,"distance_ly":null,"distance_method":null,"ra_deg":188.56620833333332,"dec_deg":13.075333333333333,"epoch_ra_deg":188.905545,"epoch_dec_deg":12.927227,"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":"Virgo","discovered":"1784","featured":false,"url":"https://spacecatalog.org/object/ngc-4531","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":12.36,"h_mag":8.99,"j_mag":9.59,"k_mag":8.76,"redshift":0.00031,"hubble_type":"S0-a","wikidata_id":"Q1112297","redshift_cmb":0.0013929379826411736,"discovered_by":"William Herschel","ngc_type_code":"G","major_axis_arcmin":3.03,"minor_axis_arcmin":1.97,"wikipedia_article":"NGC 4531","position_angle_deg":155,"surface_brightness":23.4,"radial_velocity_km_s":93},"designations":[{"catalog":"2MASX","designation":"2MASX J12341584+1304318"},{"catalog":"IRAS","designation":"IRAS 12317+1321"},{"catalog":"IRAS","designation":"IRAS F12317+1321"},{"catalog":"LEDA","designation":"LEDA 41806"},{"catalog":"MCG","designation":"MCG +02-32-141"},{"catalog":"NGC","designation":"NGC 4531"},{"catalog":"PGC","designation":"PGC 41806"},{"catalog":"SDSS","designation":"SDSS J123415.88+130431.1"},{"catalog":"TYC","designation":"TYC 880-751-1"},{"catalog":"UGC","designation":"UGC 7729"}],"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."}