The WFC/CCD consists of two 4096 x 2048 charge-coupled devices that are sensitive from the near UV to the near IR. They are thinned, backside-illuminated devices manufactured by Scientific Imaging Technologies (SITe). They are butted together along their long dimension to create an effective 4096 × 4096 array with a gap corresponding to approximately 50 pixels between the chips. The CCD camera design incorporates a warm dewar window, designed to prevent buildup of contaminants on the window that cause a loss of UV throughput.
A summary of the ACS CCD performance is given in Table 4.1.
The HRC CCD is a flight-spare STIS 1024 ×1024 CCD, also manufactured by SITe. It is a thinned, backside-illuminated device, but is coated using a process developed by SITe to provide good quantum efficiency in the near-ultraviolet. The performance characteristics and specifications are given in Table 4.1
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