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The High Speed Photometer (HSP) was a scientific instrument installed on the Hubble Space Telescope. It was one of the instruments on Hubble at launch, but couldn't be used successfully due to the optical problems initially encountered by the telescope. During the first servicing mission, in December 1993, it was replaced by the Corrective Optics Space Telescope Axial Replacement (COSTAR), which corrected the optical problem for the remaining instruments.