THE UNITED KINGDOM INFRARED TELESCOPE
ANNUAL REPORT
1997

5. Longer-Term Plans

Part of the longer term programme endorsed by the Williams Panel was a move towards developing UKIRT as a wide-field telescope. We have begun to pursue this option in more detail and a number of designs intended to deliver high-quality imaging over a 30 arcmin square FOV have been examined. This is not easy to implement in the IR on a 4m telescope like UKIRT; in particular the requirements on the one hand for image stabilisation to remove telescope micro-vibrations and hence a large bandwidth (which is facilitated by a small and agile secondary mirror), and on the other for a wide field of view (which calls for a fast f/ratio and hence a large secondary mirror), are challenging to reconcile.

At the time of writing several options are under study, including a a Cassegrain focus folded ahead of the primary, and a ``forward Cassegrain'' focus above the primary, operating at f/9 or thereabouts. A proposal for a wide-field option has been strongly endorsed by the PPARC Astronomy Committee but further progress awaits decisions by the Ground-Based Facilities Committee. In the more distant future a multi-object spectroscopic capability is a popular goal.

In the longer term the main working f/ratio of UKIRT will probably be altered to f/16 to facilitate compatibility with Gemini instrumentation. We plan to explore further the possibility of making the new secondary an adaptive system, able to provide low-order corrections over small fields of view to all instruments on UKIRT.