guide telescope


Also found in: Acronyms.

guide telescope

A telescope carried upon the same mounting as one used for photography or with instruments, to ensure that the camera, etc., is accurately guided for the whole of an exposure, which may be of many hours duration. For this duty a high magnification and an illuminated graticule are required. The telescope drives must also be provided with slow motions in both axes so that corrections can be applied manually as the selected guide star begins to drift from the cross wires. Manual guidance may now be avoided by using automatic devices – autoguiders – that monitor the position of the guide star image electronically and adjust the drive to hold it steady.
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