The TV camera, mounted on the one of the spider arms, is used to provide accurate pointing information for the telescope. The camera was built by Videospection (formerly EDO-Western). A 9 x 12 arcmin field surrounding the source is reflected from the aperture disk and reimaged by a transfer lens onto the face of the TV camera. The camera incorporates an RCA 4804 Silicon Integrating Target (SIT) vidicon tube and a number of neutral density filters to permit observation of targets as faint as V=17 or as bright as V=-4. The TV image is digitized in the DEP, using a 4 bit A/D converter, and stored in a video RAM. The image update rate depends on a number of factors (such as the amount of processing time required to calculate centroids, or the integration time needed for faint targets, etc.), but typically varies from 2 to 16 seconds. The digitized image is displayed on the Shuttle's Closed Circuit TV (CCTV) system and used by the crew to center the source in the spectrometer aperture at the start of an observation. Centering is accomplished by issuing commands to the IPS with a manual pointing controller (joy stick) or from an error signal generated by the DEP. After an observation is started, the TV image is used to provide tracking information from selected guide stars in the field.