This proposal requests partial support for expansion of the millimeter wave interferometer at Owens Valley Radio Observatory to an array of six telescopes with fifteen simultaneous baselines. The instrument is currently operating in the 1.3 and 2.6 mm bands with three 10.4 m high accuracy telescopes equipped with low noise SIS receivers. The interferometer has been used very successfully for high resolution aperture synthesis mapping of the molecules in planetary atmospheres, in the circumstellar envelopes of evolved stars, in local star forming regions, and in nearby galaxies. The major element of this project is the construction of three additional telescopes, each equipped with dual frequency front end receivers. The digital spectroscopic correlator will be expanded to handle 15 simultaneous baselines with up to 500 MHz bandwidth. The proposed expansion will result in an order of magnitude increase in speed for the array and similar increase in the dynamic range of the data through implementation of self calibration procedures. The system will be extremely versatile with the capability for mapping both primary millimeter bands, dual polarization measurements and full imaging capability on all angular scales greater than 1". The highest resolution will be similar to that of the best optical imaging obtained with ground- based telescopes. It is proposed that the three new telescopes be funded with equivalent contributions by Caltech, the NSF, and the University of Toronto. The budget submitted here is for NSF support of one of the three new telescopes with its associated electronics. The instrument will be run as an open facility with extensive use by researchers outside Caltech.
