Imaging faint brown dwarf companions close to bright stars with a small,
  well-corrected telescope aperture
  We have used our 1.6 m diameter off-axis well-corrected sub-aperture (WCS) on
the Palomar Hale telescope in concert with a small inner-working-angle (IWA)
phase-mask coronagraph to image the immediate environs of a small number of
nearby stars. Test cases included three stars (HD 130948, HD 49197 and HR7672)
with known brown dwarf companions at small separations, all of which were
detected. We also present the initial detection of a new object close to the
nearby young G0V star HD171488. Follow up observations are needed to determine
if this object is a bona fide companion, but its flux is consistent with the
flux of a young brown dwarf or low mass M star at the same distance as the
primary. Interestingly, at small angles our WCS coronagraph demonstrates a
limiting detectable contrast comparable to that of extant Lyot coronagraphs on
much larger telescopes corrected with current-generation AO systems. This
suggests that small apertures corrected to extreme adaptive optics (ExAO)
levels can be used to carry out initial surveys for close brown dwarf and
stellar companions, leaving followup observations for larger telescopes.
