The 3.8 meter United Kingdom Infrared Telescope (UKIRT) is
the largest telescope
in the world dedicated solely to observations at infrared wavelengths
micron and 30 microns. Because seeing is better in the infrared than
wavelengths, and because the telescope's optical performance has been
image quality is better than that of optical telescopes of similar size.
In fact at a
wavelength of 2 microns (the K band) the best UKIRT images thus far
in diameter. Rapid controlled movements of this secondary nirror
helps eliminate image
motion due to the atmosphere (seeing fluctuations), windshake of the
some tracking imperfections.
When I visited Hawaii a few years ago, I was invited by the
kind staff at UKIRT to
spend the night with them at an observing session. Here is their control
three other people were there -- the telescope operator, an english
astronomy and his graduate student. They were doing infrared spectroscopy
variety of stars that night.