Session 46 - Radio Astronomy, Yesterday, Today and Tomorrow - II.
Oral session, Tuesday, June 11
Union Theater,

## [46.01] The Millimeter Array

R. L. Brown (NRAO)

The Millimeter Array (MMA) is the second highest priority among the Bahcall Committee's recommendations for new large ground-based facilities in the decade of the 1990s. It is expected that the NSF will support the recommendation and begin construction of the revolutionary MMA synthesis telescope in the very near future.

The MMA consists of forty 8-m antennas designed to operate throughout the millimeter/submillimeter atmospheric windows that are accessible from a high altitude site. Scientifically, the MMA will provide high fidelity images, both spectroscopic and continuum, of thermal objects--planets, stars, interstellar molecular clouds, protostars, galactic disks, and cosmologically distant protogalaxies. The sub-arcsecond angular resolution of the MMA is needed so that the MMA images can complement those of the HST and the next-generation infrared telescopes.

The principal technical challenges facing the MMA include the following: \beginitemize \item Location of a site with low opacity and good atmospheric stability; \item Design of a high performance antenna; \item Design of SIS mixers with quantum-limited performance; \item Design of a wideband, 16 GHz, signal transmission system and correlator; \item Demonstration of an effective phase calibration technique; \item Design of antenna configurations for imaging both high brightness compact sources and very low brightness extended emission. \enditemize The MMA technical design is being carried out as a partnership between the NRAO, OVRO and BIMA called the MMA Development Consortium (MDC). It is anticipated that the MMA will have substantial involvement from international partners; such a collaboration is now being forged that will meld the capabilities of the MMA with those of other projects and serve to enhance the scientific capabilities of all.

Extensive information on the MMA can be found on the WWW via http://www.tuc.nrao.edu/mma.html