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The German REceiver for Astronomy at Terahertz Frequencies (GREAT) is a Principal Investigator class Science Instrument.
Principal Investigator: Jürgen Stutzki, University of Cologne
Instrument Team Pages: http://www3.mpifr-bonn.mpg.de/div/submmtech/heterodyne/great/greatmain.html
GREAT is a dual channel heterodyne instrument that will provide high resolution spectra (up to R=108) in several frequency windows in the 0.490–4.747 THz range. The front-end unit consists of two independent dewars, each containing a set of mixers. Offered for Cycle 7 are is the seven-beam array upGREAT in its Low Frequency Array configuration for the [CII] line at 158 μm and High Frequency Array configuration for the [OI] line. Also available for Cycle 7 are all four 4GREAT bands at the following frequency ranges: 490–635 GHz (Herschel/HIFI band 1), 890–1100 GHz (Herschel/HIFI band 4), 1200–1500 GHz (GREAT L1 channel), and 2490–2590 GHz (GREAT M channel). The backend for each mixer is a Fast Fourier Transform spectrometer (XFFTS). Each XFFTS has 2 GHz bandwidth and 64,000 channels providing a resolution of 44 kHz. The beam size of GREAT is diffraction limited (14.1” at 158 μm).
Examples of GREAT scientific observations and summary of specifications: GREAT Flyer
Information applicable to the current observing cycle, Cycle 6, can be found in the GREAT chapter of the Cycle 6 Observer's Handbook. Those submitting proposals for Cycle 7 must refer to the GREAT chapter of the Cycle 7 Observer's Handbook. Be sure that you are referencing the correct version of the handbook!