Astronomical instrumentation

Abstract:

By the end of 2001, the two Gemini telescopes will be in full operation, with the UK community having access to about 70 nights per year on each. With the WHT, UKIRT and the AAT, the community has access to over 600 nights per year of 4 m time. It is clear that most programmes will continue to he conducted on our existing telescopes, with Gemini being used only where the programmes cannot be completed on the 4 m instruments. Gemini has the advantages of large collecting area and active optics to ensure that observations are site-limited. However it also has a restricted field of view (<10 arcmin) and, initially will have a restricted instrument suite. The excellent sites and ability to apply aluminium or silver coatings to the telescope mirrors will ensure high throughput. Gemini is well-suited for deep observation over small fields. with the best results obtained over fields where tip-tilt or higher degrees of correction are effective (3 arcmin). The largest gains arise where the full gain of the increased area is realised, in near-diffraction-limited observations, e.g at thermal infrared wavelengths and with adaptive correction in the near-infrared, and in photon-starved applications such as high spectral resolution, faint object spectroscopy. Many programmes carried out with Gemini will rely on supporting observations from 4 m telescopes for target selection and complementary observations such as sample completion, simultaneous measurements in different wavebands etc. In the next decade, the UK will have access of right to almost one half of an 8 m telescope in a world where about a dozen 8-10 m class telescopes will be in operation. We enjoy a much greater fraction of the total 4 m telescopes and it will be imperative that they are used effectively with Gemini in order to ensure that our highest priority scientific programmes are completed efficiently. (C) 2001 Elsevier Science B.V. All rights reserved.