THE UNITED KINGDOM INFRARED TELESCOPE
ANNUAL REPORT
1995 AND 1996

6. UKIRT Upgrades

6.4. Bottom-End Systems

6.4.3. Fast Guider

The Fast Guider is carried below the crosshead, attached to an Interface Unit which allows selection of a straight-through path (to the Scanco TV for field identification), a currently-unused auxilliary path and the Fast Guider, in which configuration 95% of the light is passed to the fast guider CCD system. (The remaining 5% has proved valuable for diagnostics.)

In addition to adaptive tip/tilt corrections, the Fast Guider is also capable of determining adaptive focus corrections. However the dynamic range of the piezo-electric actuators at the secondary is currently too small to correct the focus position fluctuations seen. It may later prove desirable to feed smoothed focus information to the hexapod for ``active'' rather than ``adaptive'' focus correction. Installation of a focus-tracking system, to maintain focus as temperature and telescope attitude changes, is planned for 1997. ⁶