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5.9. The Advanced Camera for Surveys (ACS)

The ACS will be installed during the third servicing mission in the bay currently occupied by the FOC. It has been designed as an optimal camera for all faint ultraviolet targets. The ACS has three cameras: the Wide Field Camera (WFC) has high throughput, a large field and will mostly be obtaining images in the I band; the High Resolution Camera (HRC) is critically sampled at 5000Å and includes a coronograph; the Solar Blind Camera is optimized for far UV observations. Some characteristics of these cameras are included in Table 24.

Table 24. ACS characteristics.

Wide Field Camera High Resolution Camera Solar Blind Camera

Field of View 200" x 200" 26" x 26" 26" x 26"
Number of Pixels 4000 x 4000 1000 x 1000 1000 x 1000
Pixel Size 0.05" 0.025 0.025
Bandwidth 4000Å - 1µm 2000Å - 1µm 1150Å- 1700Å

The set of filters have been chosen as to complement those of the Sloan Digital Sky Survey. With the ACS it will be possible to observe multiple Lyman alpha forest systems with sufficient resolution as to separate the D and H contrib= utions. The position of the WFC and HRC in HST's focal plane (parallel to the V2 and V3 axis) makes it possible to obtain mosaiced images while the Guide Stars are stepping along the directions of the FGS.

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