Ultraluminous Infrared Galaxies (ULIRGs) represent a population that is among the most extreme in our universe, emitting an extraordinary amount of energy at infrared wavelengths from dust heated by either prolific star formation and/or the presence of an active galactic nucleus (AGN). We have observed several nearby ULIRGs with CARMA in four configurations, including the longest baseline (up to 2 km) A-array configuration, which has a resolution of ~0.15’’ at 1.3 mm. We have utilized the Paired Antenna Calibration System (PACS) for atmospheric calibration in the longer baseline configurations. In this calibration system, Sunyaev-Zeldovich Array (SZA) antennas were paired with CARMA antennas to allow for a continuous measurement of the atmospheric phase screen on long baselines over time intervals from two seconds to several hours. We performed a variety of tests on bright quasars to confirm the PACS calibration methodology. We present these results along with our scientific results from observations of Arp 220 and other nearby ULIRGs.