{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.818","julian_year":2026.818,"time":"2026-10-26T15:01:30.686Z","years_from_j2000":26.818,"frame":"date","applied":"Proper motion, then precession and nutation. The catalogued position is carried along the great circle the object's own published motion puts it on, at a constant velocity, from the epoch that position was measured at, 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. The motion runs from position_epoch_jyear where the upstream publishes one — a timed pulsar's position belongs to the year it was timed — and from J2000 where it does not. 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-4645","name":"NGC 4645","class":"elliptical_galaxy_e","category":"galaxy","object_type":"Elliptical galaxy E","mag":11.83,"mag_band":"V","abs_mag":null,"abs_mag_band":null,"distance_ly":135045032.50049725,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":191.04162499999998,"dec_deg":-41.749944444444445,"epoch_ra_deg":191.41145,"epoch_dec_deg":-41.897647,"epoch_moved_arcsec":null,"pm_ra_mas_yr":null,"pm_dec_mas_yr":null,"position_epoch_jyear":null,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Centaurus","discovered":"1834","featured":false,"url":"https://spacecatalog.org/object/ngc-4645","source":{"id":"openngc","name":"OpenNGC","url":"https://github.com/mattiaverga/OpenNGC","license":"CC-BY-SA-4.0","attribution":"OpenNGC, Mattia Verga (github.com/mattiaverga/OpenNGC). Fields derived from it stay under CC BY-SA 4.0.","commercial_use":"allowed"},"radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"b_mag":12.88,"h_mag":8.72,"j_mag":9.37,"k_mag":8.44,"v_mag":11.83,"redshift":0.00865,"hubble_type":"E","wikidata_id":"Q1113153","redshift_cmb":0.00959776948925306,"discovered_by":"John Frederick William Herschel","ngc_type_code":"G","uncertainties":{"distance_ly":[15094696.145428257,15094696.145428257]},"major_axis_arcmin":1.97,"minor_axis_arcmin":0.89,"position_angle_deg":46,"surface_brightness":23.18,"radial_velocity_km_s":2583},"designations":[{"catalog":"2MASX","designation":"2MASX J12440998-4144596"},{"catalog":"ESO","designation":"ESO 322-066"},{"catalog":"ESO","designation":"ESO 322-66"},{"catalog":"ESO-LV","designation":"ESO-LV 322-0660"},{"catalog":"LEDA","designation":"LEDA 42879"},{"catalog":"MCG","designation":"MCG -07-26-037"},{"catalog":"NGC","designation":"NGC 4645"},{"catalog":"PGC","designation":"PGC 42879"}],"updated_at":"2026-10-01T09:42:28.932Z","citation":{"plain":"SpaceCatalog. NGC 4645 [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/ngc-4645","bibtex":"@misc{spacecatalog_ngc-4645,\n  author       = {{SpaceCatalog}},\n  title        = {{NGC 4645}},\n  howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},\n  year         = {2026},\n  url          = {https://spacecatalog.org/object/ngc-4645},\n  note         = {Catalogue entry, data release DR1 (2026-08-21). Values from OpenNGC.}\n}","url":"https://spacecatalog.org/object/ngc-4645","release":"DR1","doi":null},"references":[],"attribution":"Data from SpaceCatalog.org. Each record names its upstream in `source`, with that producer's terms in `source.license`, the acknowledgement it asks for in `source.attribution`, and whether its terms allow commercial use in `source.commercial_use`; those terms govern the record, and citing SpaceCatalog does not discharge them."}