{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.819","julian_year":2026.819,"time":"2026-10-27T05:25:53.363Z","years_from_j2000":26.819,"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-5646","name":"NGC 5646","class":"spiral_galaxy_sb","category":"galaxy","object_type":"Spiral galaxy Sb","mag":15.03,"mag_band":"B","abs_mag":null,"abs_mag_band":null,"distance_ly":417428653.06667054,"distance_method":"redshift (CMB frame), flat ΛCDM with H0 = 70 km/s/Mpc","ra_deg":217.39170833333333,"dec_deg":35.46194444444445,"epoch_ra_deg":217.673507,"epoch_dec_deg":35.341547,"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":"Boötes","discovered":"1881","featured":false,"url":"https://spacecatalog.org/object/ngc-5646","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":15.03,"k_mag":11.2,"redshift":0.02866,"hubble_type":"Sb","wikidata_id":"Q1121712","redshift_cmb":0.029237990530199154,"discovered_by":"Édouard Stephan","ngc_type_code":"G","uncertainties":{"distance_ly":[22065916.050102018,22065916.050102018]},"major_axis_arcmin":1.19,"minor_axis_arcmin":0.45,"position_angle_deg":79,"surface_brightness":23.42,"radial_velocity_km_s":8469},"designations":[{"catalog":"IRAS","designation":"IRAS 14274+3540"},{"catalog":"IRAS","designation":"IRAS F14274+3541"},{"catalog":"LEDA","designation":"LEDA 51779"},{"catalog":"MCG","designation":"MCG +06-32-045"},{"catalog":"NGC","designation":"NGC 5646"},{"catalog":"PGC","designation":"PGC 51779"},{"catalog":"SDSS","designation":"SDSS J142934.01+352743.0"},{"catalog":"UGC","designation":"UGC 9312"}],"updated_at":"2026-10-01T09:42:28.932Z","citation":{"plain":"SpaceCatalog. NGC 5646 [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/ngc-5646","bibtex":"@misc{spacecatalog_ngc-5646,\n  author       = {{SpaceCatalog}},\n  title        = {{NGC 5646}},\n  howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},\n  year         = {2026},\n  url          = {https://spacecatalog.org/object/ngc-5646},\n  note         = {Catalogue entry, data release DR1 (2026-08-21). Values from OpenNGC.}\n}","url":"https://spacecatalog.org/object/ngc-5646","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."}