NGC 643

{{Short description|Star cluster in the constrellation Hydrus}}

{{Sky|01|35|01.43|-|75|33|24.7|1}}{{Infobox open cluster|name=NGC 643|constellation=Hydrus|image=File:NGC 643 DECam.jpg|appmag_v=13|caption=NGC 643 with DECam|dec={{DEC|-75|33|24.7}}|dist_ly=~200,000 ly|epoch=J2000|names=ESO 29-SC50|ra={{RA|01|35|01.43}}|radius_ly=|size_v=1.50 arcmin|image_size=250}}

NGC 643 is an open cluster located on the far outskirts of the Small Magellanic Cloud in the southern constellation of Hydrus, approximately 200,000 light-years from Earth.{{Cite web|url=http://ned.ipac.caltech.edu/?q=byname&out_csys=Equatorial&corr_z=1&omegav=0.73&extend=no&omegam=0.27&img_stamp=YES&out_equinox=J2000.0&objname=NGC%20643&list_limit=5&of=pre_text&hconst=73&obj_sort=RA%20or%20Longitude&keyword=objname|title=NGC 643 NASA/IPAC Extragalactic Database Results|website=ned.ipac.caltech.edu|access-date=November 1, 2018}}{{Cite web|url=http://spider.seds.org/ngc/revngcic.cgi?NGC643|title=Revised NGC Data for NGC 643|website=spider.seds.org|access-date=November 1, 2018}}{{Cite web|url=http://cseligman.com/text/atlas/ngc6.htm#643|title=New General Catalog Objects: NGC 600 - 649|website=cseligman.com|access-date=November 1, 2018}} Due to their close proximity to NGC 643, the open cluster ESO 29-SC44 and the galaxies PGC 6117 and PGC 6256 are also designated NGC 643A, NGC 643B and NGC 643C, respectively. NGC 643 is relatively old. Its brightest stars have an apparent magnitude of 19.{{Cite journal|last=de Vaucouleurs|first=G.|title=NGC 643: A New Outlying Cluster of the Small Magellanic Cloud |date=1957|journal=Publications of the Astronomical Society of the Pacific|volume=69|issue=408|pages=252–255|jstor=40676443|doi=10.1086/127060|bibcode=1957PASP...69..252D|doi-access=free}}

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