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Session 46 - Radio Astronomy, Yesterday, Today and Tomorrow - II.
Oral session, Tuesday, June 11
Union Theater,
The Submillimeter Wavelength Array (SMA), is under construction and is expected to begin operations in 1998 on Mauna Kea, near the CSO and JCMT facilities. The array will consist initially of six 6--meter diameter antennas arranged on the sides of Reuleaux triangles. Four configurations will be available with diameters of approximately 24, 64, 171 and 470 m. Each antenna will be equipped with a cryostat at its Nasmyth focus and will accept eight receivers covering all useable bands from 230 to 850 GHz. The maximum angular resolution will vary from 0.4 to 0.1 '' over the frequency range. Signal processing will be performed on a special purpose XF correlator, which is based on a chip developed at the Haystack Observatory and the NASA/SERC for VLSI Design. The correlator will accept two channels (for either dual polarization or dual frequency operation) from each antenna of 2 GHz bandwidth each. The subchannel bandwidth is 104 MHz. Spectral resolutions as fine as 0.6 km/s will be available with full processing capacity. The Smithsonian Astrophysical Observatory is the general contractor for the project. The first antenna is expected to be assembled and ready for receiver installation in July 1996. The antennas have reflector backup structures constructed of carbon fiber tubes and steel nodes. Each primary reflector consists of 72 machined aluminum panels, which have rms accuracies of about 5 microns. The overall reflector surface is expected to have an rms accuracy of 12 microns. In the laboratory, receiver temperatures of 25, 30 and 65 K(DSB) have been achieved at 230, 345 and 460 GHz, respectively, for SIS mixer receivers with junctions fabricated at JPL. Initial interferometric tests on celestial sources are planned for early 1997 at the assembly site at Haystack Observatory in Westford, MA. An agreement for collaboration has been reached between SAO and the Institute of Astronomy and Astrophysics of the Academy of Science (Taiwan). ASIAA will initially provide two additional antennas to the array. Preparations are also being made to include the 15-m JCMT and 10-m CSO telescope in the array on a part time basis.
