  We present initial results of an ongoing search for interferometric
calibrators at submillimeter (sub-mm) wavelengths with the Submillimeter Array
(SMA). Powerful radio galaxies are commonly used as calibrators at centimeter
and millimeter wavelengths, but many are not strong enough to serve as
calibrators at sub-mm wavelengths because of their rapidly declining flux
densities toward shorter wavelengths. The inability to find a calibrator close
to the target source may limit or even prevent us from imaging many interesting
sources at sub-mm wavelengths. Here, we investigate whether high-mass
protostellar objects and ultracompact HII regions can serve as useful
calibrators for the SMA. The dust emission associated with these objects makes
them among the brightest sub-mm sources in the sky. Our observations at 0.85 mm
(345 GHz) with an angular resolution of ~3" reveal that although a large
fraction of the dust emission originates from an extended ``halo'' component, a
compact unresolved component often remains that when sufficiently strong may
serve as a useful calibrator. These observations also provide a first glimpse
at the small-scale distribution of dust around ultracompact HII regions and
high-mass protostellar objects at sub-mm wavelengths. We discuss the origin of
the core-halo structure seen in many sources, and conclude with suggestions for
future searches for calibrators with the SMA.
