and planet forming star systems. Spectral-line observations can be used to identify particular molecules in molecular clouds, study their distribution and chemistry and determine gas velocity gradients across astronomical objects (because of the doppler effect). SCUBA The older continuum single pixel UKT14 bolometer receiver was replaced around 1995 by the Submillimetre Common-User Bolometer Array (SCUBA). This instrument operated simultaneously at wavelengths of 450 and 850 micron (with 91 and 37 pixels, respectively), and was sensitive to the thermal emission from interstellar dust. SCUBA was a ground-breaking instrument, among the most high-impact astronomy instruments from 1997-2003; it was retired from service in 2005, and is now in the National Museum of Scotland. SCUBA-2 SCUBA was succeeded by SCUBA-2, which was commissioned in 2011. This ground-breaking camera consists of large arrays of superconducting transition edge sensors with a mapping speed hundreds of times larger than SCUBA. It has 5120 array elements at both 450 and 850 micron wavelength (10,240 total pixels). It has been conducting the JCMT legacy surveys since November, 2011, including the SCUBA-2 All Sky Survey, and was made available for general astronomical observations in February, 2012. Two ancillary instruments, FTS-2 and POL-2, add spectroscopic and polarimetric capabilities to SCUBA-2. Spectral line detectors The JCMT is also equipped with two heterodyne receivers, which allow submillimetre spectral line observations to be made. The spectral-line mapping capabilities of the JCMT have been greatly enhanced by the commissioning in 2006 of HARP, a 350 GHz, 16 element heterodyne array receiver. Both instruments can be used in conjunction with the JCMT's new digital autocorrelation spectrometer, ACSIS. One of the heterodyne receivers is named Namakanui ("Big-Eyes"), referring to big-eyed fish that swim in Hawaiian waters at night. This receiver can operate at 86, 230, and 345 GHz. See also Far infrared astronomy Radio astronomy SCUBA-2 All Sky Survey Submillimetre astronomy References External links JCMT homepage (new) Slicing the Universe with HARP/ACSIS - A New Look at Orion Astronomical observatories in Hawaii Submillimetre telescopes Radio telescopes James Clerk Maxwell Buildings and structures in Hawaii County, Hawaii Astronomy in the United Kingdom