  Keck near-infrared images of Neptune from UT 26 July 2007 show that the cloud
feature typically observed within a few degrees of Neptune's south pole had
split into a pair of bright spots. A careful determination of disk center
places the cloud centers at -89.07 +/- 0 .06 and -87.84 +/- 0.06 degrees
planetocentric latitude. If modeled as optically thick, perfectly reflecting
layers, we find the pair of features to be constrained to the troposphere, at
pressures greater than 0.4 bar. By UT 28 July 2007, images with comparable
resolution reveal only a single feature near the south pole. The changing
morphology of these circumpolar clouds suggests they may form in a region of
strong convection surrounding a Neptunian south polar vortex.
