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Previous: Design of the A&G unit
Up: The Cassegrain A&G Box
Next: Slit viewing
Previous Page: Design of the A&G unit
Next Page: Slit viewing
Object acquisition is carried out via an extendable probe carrying a mirror feeding a Westinghouse ISEC TV camera. When used direct ( not the usual mode of acquisition when ISIS is in use), this provides a 1.5 arcmin field at the telescope scale of 4.51 arcsec/mm. It is possible to insert a focal reducing system, which provides a larger field of 4 arcmin at a scale of 12 arcsec/mm. The TV camera is provided with a filter wheel with six filter positions. The available filters are CLEAR (UBK7), B (BG 28), V (BG 38), R (RG 630) and EMPTY (no filter). Note that the empty position will give a different focus position for the TV. These filters do not give a standard photometric system and the Johnson letters are given for guidance only.
The TV can be focussed independently to compensate for different filter thicknesses.