  We present 0.15" resolution observations of the 227 GHz continuum emission
from the circumstellar disk around the FU-Orionis star PP 13S*. The data were
obtained with the Combined Array for Research in Millimeter-wave Astronomy
(CARMA) Paired Antenna Calibration System (C-PACS), which measures and corrects
the atmospheric delay fluctuations on the longest baselines of the array in
order to improve the sensitivity and angular resolution of the observations. A
description of the C-PACS technique and the data reduction procedures are
presented. C-PACS was applied to CARMA observations of PP 13S*, which led to a
factor of 1.6 increase in the observed peak flux of the source, a 36% reduction
in the noise of the image, and a 52% decrease in the measured size of the
source major axis. The calibrated complex visibilities were fitted with a
theoretical disk model to constrain the disk surface density. The total disk
mass from the best fit model corresponds to 0.06 \msun, which is larger than
the median mass of a disk around a classical T Tauri star. The disk is
optically thick at a wavelength of 1.3 mm for orbital radii less than 48 AU. At
larger radii, the inferred surface density of the PP 13S* disk is an order of
magnitude lower than that needed to develop a gravitational instability.
