  We show that candidate contact binary asteroids can be efficiently identified
from sparsely sampled photometry taken at phase angles >60deg. At high phase
angle, close/contact binary systems produce distinctive lightcurves that spend
most of the time at maximum or minimum (typically >1mag apart) brightness with
relatively fast transitions between the two. This means that a few (~5) sparse
observations will suffice to measure the large range of variation and identify
candidate contact binary systems. This finding can be used in the context of
all-sky surveys to constrain the fraction of contact binary near-Earth objects.
High phase angle lightcurve data can also reveal the absolute sense of the
spin.
