Editing Advanced Camera for Surveys (section)

===High-Resolution Channel (HRC)===
[[File:Mars close encounter (captured by the Hubble Space Telescope).jpg|thumb|200px|right|Hubble's ACS/HRC captures [[Mars]] during its 2003 opposition, yielding the sharpest visible-light color [[RGB color model|(RGB)]] photo yet taken from Earth. At about 8 km / pixel, various martian craters and markings are revealed. The ACS "[[William George Fastie|Fastie finger]]" is blocking light on the left.<ref>{{Cite web|url=http://hubblesite.org/image/1382/news_release/2003-22|title=HubbleSite: Image - Sharpest Ever Color View of Mars|website=hubblesite.org}}</ref>]]
The HRC, which has been permanently disabled since 2007 due to an electrical fault, provided ultra-sharp views over a smaller field-of-view.

The HRC detector was a 1024×1024 SITe CCD  which had a smaller field-of-view (26"×29") than the WFC but twice the spatial sampling (0.025" per pixel). This detector was also significantly more sensitive than the WFC at near-ultraviolet wavelengths (<350&nbsp;nm).

The channel used two light suppression options for imaging faint objects around bright stars, improving the contrast of targets close to bright sources by tenfold. The first was a commandable coronagraphic mask that included two occulting spots, one of diameter 1.8" at the center of the field and the other of diameter 3.0" nearer to a corner. The first spot was the most popular of the two, for example, for imaging circumstellar disks around nearby bright stars or the host galaxies of luminous quasars. The second was the so-called [[William George Fastie|Fastie]] Finger, 0.8" in width and 5" in length, located at the entrance of the HRC dewar window.