The United Kingdom Infrared Telescope

by Douglas Pierce-Price, JAC

The United Kingdom Infrared Telescope (UKIRT) is one of two telescopes operated by the Joint Astronomy Centre, the other being the James Clerk Maxwell Telescope (JCMT).

UKIRT sees the universe with infrared light, the invisible heat radiation that lies beyond red at the edge of a rainbow. It was originally designed as a relatively simple 'light collector', but its 3.8-meter diameter mirror is of extremely high quality. Advanced upgrades to the rest of the telescope have allowed UKIRT to take full advantage of the excellent conditions on Mauna Kea.

UKIRT detects its light with a suite of advanced instruments, including newcomers Michelle (the Mid-Infrared Echelle Spectrograph) and UIST (the UKIRT Imager Spectrometer). These 'workhorse' instruments are capable of performing the three main types of infrared observations: imaging, spectrometry, and polarimetry.

Michelle has been used to observe young stars which were previously hidden in cocoons of the dust and gas from which they formed. Observations at 'near infrared' wavelengths show the surrounding dusty material, but Michelle's view at longer 'mid infrared' wavelengths penetrates the dust to reveal the young stars within.

UKIRT also studies brown dwarfs, mysterious objects sometimes referred to as 'failed stars'. They are more massive than gas giant planets like Jupiter, but are not quite massive enough to shine like normal stars. UKIRT has significantly advanced our understanding of them over the last few years.

The new instrument UIST was built at the Astronomy Technology Centre in Edinburgh, Scotland. On its first night at UKIRT it was used to map part of the Omega Nebula, a gas cloud where new stars are forming. Located 5000 light years from Earth, the nebula is a near neighbor in astronomical terms. The intense ultraviolet radiation from young, hot stars blasts the atoms in clouds of interstellar gas, making them glow brightly.

UIST also has a revolutionary 'image slicer', which slices the light from an astronomical target into thin sections. Each slice is then spread out to make a spectrum, like the rainbows produced when light passes through a glass prism. Astronomers recombine these spectra to get a three-dimensional view of the interactions between stars, cosmic dust and gas in complex objects like galaxies.

Shortly after UIST started observations it was trained upon the most distant quasar known, about 13 billion light years from Earth. Quasars are exceptionally luminous galaxies, far brighter than can be explained by normal starlight. They are powered by the release of gravitational energy as matter is pulled toward a supermassive black hole at their centers, and their extreme brightness makes them visible at great distances. By looking at gas swirling around the quasar's core, scientists were able to 'weigh' this black hole at the edge of the universe. It has the mass of three billion Suns!

A forthcoming wide-field camera 'WFCAM' will allow UKIRT to undertake extremely ambitious surveys, studying huge areas of the infrared sky to unprecented depths.

UKIRT is funded by the United Kingdom. It was opened in October 1979.

You can find some more technical information in a previous article about UKIRT.