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 Fastie Finger, 0.8" in width and 5" in length, located at the entrance of the HRC dewar window. Solar Blind Channel (SBC) The Multi Anode Microchannel Array (MAMA) of the SBC is a low-background photon-counting device optimized for the ultraviolet in the wavelength range of 115–170 nm. It consists of a photocathode, a microchannel plate, and an anode array. Its spatial sampling is 0.034"x0.030" per pixel and its field-of-view is 34.6"×30.0". The ACS SBC is in fact a flight spare from the Space Telescope Imaging Spectrograph (STIS). ACS problems and fixes 2006–2009 On 25 June 2006 ACS suffered an electronic failure. It was powered up successfully on its redundant (side-2) electronics. The instrument subsystems, including the CCD detectors, proved to be working after engineering tests, and ACS resumed science operations on July 4, 2006. On 23 September 2006, the ACS again failed, though by 9 October the problem had been diagnosed and resolved. On January 27, 2007, the ACS failed due to a short circuit in its backup power supply. The instrument's Solar Blind Channel (SBC) was returned to operation on 19 February 2007 using the side-1 electronics. The Wide Field Channel (WFC) was returned to service by STS-125 in May 2009. The High Resolution Channel (HRC), however, remains offline. Gallery Filters and dispersers ACS possesses a set of 38 filters and dispersers distributed among three wheels. Two of these wheels are shared by the HRC and WFC light paths while the third is dedicated to the SBC. The HRC and WFC elements consist of eleven broad-band filters, one medium-band filter, five narrow-band filters, three visible and three ultraviolet polarizers, one prism for the HRC, and one grism (580–1100 nm). Four of the filters have bandpasses in the near-ultraviolet and so can be used with the HRC only. The primary broad-band filters are equivalent to the u, g, r, i, and z filters of the ground-based Sloan Digital Sky Survey (SDSS). Five