James Clerk Maxwell Telescope

The James Clerk Maxwell Telescope (JCMT) is a 15-metre submillimetre-wavelength telescope at Mauna Kea Observatory in Hawaii. It is the largest astronomical telescope in the world designed specifically to operate in the submillimetre regime (between the far-infrared and the microwave regions of the electromagnetic spectrum). It is used to study our Solar System, interstellar dust and gas, and distant galaxies.

Instrumentation

The JCMT carries two types of instruments - broadband continuum detectors and spectral-line receivers.

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The older continuum single pixel UKT14 bolometer receiver was replaced in the 1990s by the Submillimetre Common Users Bolometer Array (SCUBA). The SCUBA project was greenlighted in 1987 by the JCMT board and was in development for nearly a decade before it saw first light on the telescope. While it was not the first bolometer-array it was "unique in combining an unparallel sensitivity with an extensive wavelength range and field-of-view" http://xxx.lanl.gov/abs/astro-ph/9809122.

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SCUBA is sensitive to the thermal emission from interstellar dust. This emission is a tracer of star formation in other galaxies and gives astronomers clues to the presence, distance, and evolution history of galaxies other than our own. Within our own galaxy dust emission is associated with stellar nurserys and planet forming solar systems.

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SCUBA is ranked second only to the Hubble Space Telescope in terms of publication of high-impact astronomical research. SCUBA was retired from service in 2005. Work is currently underway on SCUBA-2, a replacement for SCUBA, that is expected to see first light in 2006 http://www.roe.ac.uk/ukatc/projects/scubatwo/whatis/summary.html.

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The JCMT is also equipped with three heterodyne receivers, which allow submillimetre spectral-line observations to be made. Spectral-line observations can be used to identify particular molecules in the interstellar medium and determine local gas velocity gradients across astronomical objects of interest. The spectral-line mapping capabilities of the JCMT will be greatly enhanced by the commissioning of HARP-B, a 350 GHz, 16 element heterodyne array receiver. HARP-B first light is expected in December 2005. HARP-B, and the other heterodyne instruments, will soon be used in conjunction with the JCMT's new digital autocorrelation spectrometer, ACSIS.

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