UKIRT, the United Kingdom Infra-Red Telescope, is a 3.8 metre (150 inch) infrared reflecting telescope, the second largest dedicated infrared (1 to 30 micrometres) telescope in the world. It is operated by the Joint Astronomy Centre in Hilo and located on Mauna Kea, Hawai'i as part of Mauna Kea Observatory. It is owned by the United Kingdom Science and Technology Facilities Council.
Based on the design of the Carlos Sanchez Telescope in Tenerife it is a Cassegrain device with a thin primary mirror, around 2/3 thinner than in other contemporary devices and weighing only 6.5 tonnes. The mirror is held in a massive steel 'cell' of 20 tonnes which is linked to the supports by Serrurier trusses. The instrument is held and pointed by a massive 'English Equatorial mounting' or yoke which sits on ball-bearings on steel piers, swinging east-west and rotating around north-south. The geometry of the mount limits the telescopes access to objects between +60 and -40 degrees of declination but it is extremely sturdy and free from deformation and so allows very accurate pointing. The telescope was built between 1975 and 1978; the mechanical systems were built by Dunford Hadfields of Sheffield and the optics by Grubb Parsons of Newcastle. Originally known as the Infrared Flux Collector it began operation in October 1979.
A UKIRT infrared survey was used to discover a redshift distance record breaking Quasar in 2011.[1] The Quasar could not be seen in visible light, but could in the longer wavelengths observed by UKIRT.[1]
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UKIRT has three Cassegrain instruments and a wide-field imager placed forward of the Cassegrain focus.
Built as a relatively cheap telescope, UKIRT has been extensively upgraded. A program of improvements from 1990 to 1998 greatly improved the imaging performance, and in 2001 the telescope delivered median infrared seeing ranging from 0.8 arcseconds at dusk to 0.5 arcseconds in the early morning [1]. Between 1998 and 2003, two major software projects were undertaken - the ORAC project providing a major upgrade to the user interface and automating telescope operations, and the OMP providing a comprehensive observation database and data feedback mechanisms. Since 2003, using these two software enhancements, UKIRT has carried out highly efficient flexible scheduling - tailoring observation execution to the prevailing weather conditions. Observations are selected from the database according to the current seeing, atmospheric water vapour, sky transparency and a science priority allocated by the telescope time allocation panel.
With the delivery of the wide-field imager WFCAM in 2004, UKIRT began a revolutionary large-scale sky survey (the UKIRT Infrared Deep Sky Survey, UKIDSS). This project takes some 80% of the available telescope time in wide-field mode. Wide-field takes some 60% of the telescope; the other 40% is devoted to operations with the Cassegrain instrumentation. In December 2008 it was announced that the telescope would be moving to wide-field mode full time [2].
It was announced on 16 December 2009 that the telescope is "subject to discussions leading to managed withdrawal" [3].
Although seeing in the infrared, the UKIRT was large for an optical telescopes and signaled a coming focus on this part of the spectrum that only grew in the coming decades.
Here is the UKIRT (then called Infrared Flux Collector) compared to the other largest optical telescopes circa 1978, only a some of these could also see in the near infrared.
| # | Name(s) / Observatory |
Image | Aperture | Spectrum | Altitude | First Light |
Special advocate |
|---|---|---|---|---|---|---|---|
| 1 | BTA-6 Special Astrophysical Obs |
238 inch 605 cm |
Visible | 2070 m (6791 ft) |
1975 | Mstislav Keldysh | |
| 2 | Hale Telescope Palomar Obs. |
200 inch 508 cm |
Visible | 1713 m (5620 ft) |
1949 | George Ellery Hale | |
| 3 | Mayall Telescope Kitt Peak National Obs. |
158 inch 401 cm |
Visible | 2120 m (6955 ft) |
1973 | Nicholas Mayall | |
| 4 | Blanco Telescope CTIO Obs. |
158 inch 401 cm |
Visible | 2200 m 7217 feet |
1976 | Nicholas Mayall | |
| 5 | Anglo-Australian Telescope Siding Spring Obs. |
153 inch 389 cm |
Visible | 1742 m (5715 ft) |
1974 | Prince Charles | |
| 6 | United Kingdom Infrared Telescope Joint Astronomy Centre |
150 inch 380 cm |
Infrared | 4205m (13,800 ft) |
1979 | ||
| 7 | ESO 3.6 m Telescope ESO La Silla Obs. |
140 inch 357 cm |
Visible Infrared |
2400 m m (7874 ft) |
1977 | Adriaan Blaauw | |
| 8 | Shane Telescope Lick Observatory |
120 inch 305 cm |
Visible | 1283 m (4209 ft) |
1959 | Nicholas Mayall |
Dedicated near infrared telescopes require a high and dry location, special instrumentation, and similar high quality mirrors and optics as for visible wavelength observations.
Other large optical infrared near infrared telescopes in 1980
| # | Name(s) / Observatory |
Image | Aperture | Spectrum | Altitude | First Light |
|---|---|---|---|---|---|---|
| 1 | United Kingdom Infrared Telescope Joint Astronomy Centre |
150 inch 380 cm |
Infrared | 4205m (13,800 ft) |
1979 | |
| 2 | ESO 3.6 m Telescope ESO La Silla Obs. |
140 inch 357 cm |
Visible Infrared |
2400 m m (7874 ft) |
1977 | |
| 3 | NASA Infrared Telescope Facility Mauna Kea Observatory |
118 inch 300 cm |
Infrared | 4205m (13,800 ft) |
1979 |
Two other large but smaller near IR telescopes were WIRO 2.3 in Wyoming, USA,[2] the Gornergrat Infrared Telescope (TIRGO, 1.5 m) in the Swiss alps, and a 1.6 m at Mont Mégantic Observatory in Canada.