At the Caltech meeting we set writing assignments for the upcoming
Berkeley meeting. These are to be 1/2 - 1 page discussions of the science
benefits of proceeding with the individual CARMA technology developments
that we discussed at Caltech. This text would be discussed at Berkeley
and would be the starting point of what would be in the NSF proposal. The
idea is for each of you to send me your text by March 5 at very latest,
so I can integrate together as a single document and send to the rest
of the SSC.


Many astronomical studies require observations over a wide range of
spatial scales of sources which are larger than the primary beam of
the antennas.  A 10 m antenna at a wavelength of $\lambda$ 1.3 mm has a
field of view of $\sim 30''$; sources larger than this require a mosaic of
interferometer and single dish observations at multiple pointing centers.

The CARMA array is well suited to imaging a wide range of spatial
scales. The different antenna diameters allow a larger range of
spatial frequencies to be sampled by interferometer observations,
and the different primary beam patterns decouple the source brightness
distribution from the primary beam illumination. However, if we can not
determine the primary beam patterns well enough, the errors will degrade
the image fidelity.

In a recent memo we present a method for deconvolving the primary beam
response from interferometric mosaic images of astronomical sources.
The measured primary beam may be time variable, non axi-symmetric and
different on each antenna in the interferometer array. The method is a
simple extrapolation of existing software which subtracts a model of the
sky brightness distribution from uvdata.  After subtracting the best
estimate of the sky brightness distribution weighted by the measured
primary beam pattern, the residual uvdata can be re-imaged to provide
an improved model of the sky brightness distribution and the process
iterated if needed until the residual uvdata are consistent with thermal
noise and other residual instrumental errors. The data are imaged using
canonical, time invariant primary beam patterns, and deconvolved using
the measured primary beam voltage patterns for each antenna.

The primary beam pattern is the product of the
voltage patterns for each antenna pair, and is complex valued if the
voltage patterns are not identical. This results in a complex valued
image of a real, total intensity, sky brightness distribution; i.e.
the image shows a polarized flux distribution which varies across the
primary beam, and any real polarization distribution is confused by
flux scattered from the total intensity by primary beam errors.
Polarization images can be corrected by subtracting a model
of the source weighted by the complex valued primary beam patterns from
the uvdata.

The CARMA telescope will address a number of outstanding problems
which require high image fidelity at ~ arcsec resolution of
sources which are larger than the primary beam. E.g. Observations
at millimeter wavelenths are key to determining the source of
particle acceleration in supernova and radio galaxies cas, crab, cyg 
with sufficient resolution to map the filaments,  hot spots, and shocks
in these sources. Mapping the fine scale structure of infalling 
molecular gas and outflows in YSO. Mapping the polarization of dust
emission across molecular clouds. These are all examples of observations
which require accurate deconvolution of the primary beam response
from mosaic images.