AAS Meeting #193 - Austin, Texas, January 1999
Session 11. Observatories, Telescopes and Instruments
Display, Wednesday, January 6, 1999, 9:20am-6:30pm, Exhibit Hall 1

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[11.19] A 345~GHz Array Receiver for HHT

A. Hungerford, C. K. Walker, C. E. Groppi (Steward Observatory)

We are constructing a 7-element, SIS heterodyne array receiver (Desert STAR) for the Heinrich Hertz Telescope (HHT) atop Mt. Graham (AZ). The array will operate in the 870~\mum atmospheric window, with a tuning range between 315 and 380~GHz. Due to the prevailing physical conditions in the interstellar medium, this wavelength range is one of the richest in the submillimeter portion of the spectrum. The 870~\mum window also has the highest atmospheric transmission of any submillimeter band. An array designed for this wavelength range will make excellent use of the telescope, the available atmospheric transmission, and provide a new perspective on stellar, chemical, and galaxy evolution in the present, as well as past epochs.

The cryostat utilizes a closed-cycle refrigerator to cool the mixers, IF amplifers and optics to 4~K. Ultimately, a cooled Martin-Puplett Interferometer (MPI) single sideband (SSB) filter will be incorporated into the system. Initially, the array will operate in double sideband (DSB) mode and use a mylar beamsplitter for local oscillator (LO) injection. Calculations indicate that LO injection via a beamsplitter should provide ample power to drive the 7-element array. The cryostat can support a second MPI for more efficient LO injection should that be necessary. First light observations with the array are planned for the fall of 1999.

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