Detection of caustic crossings of binary-lens gravitational microlensing
events is important because by detecting them one can obtain useful information
both about the lens and source star. In this paper, we compute the distribution
of the intervals between two successive caustic crossings, f(tcc​), for
Galactic bulge binary-lens events to investigate the observational strategy for
the optimal detection and resolution of caustic crossings. From this
computation, we find that the distribution is highly skewed toward short
tcc​ and peaks at tcc​∼1.5 days. For the maximal detection
of caustic crossings, therefore, prompt initiation of followup observations for
intensive monitoring of events will be important. We estimate that under the
strategy of the current followup observations with a second caustic-crossing
preparation time of ∼2 days, the fraction of events with resolvable
caustic crossing is ∼80. We find that if the followup observations can
be initiated within 1 day after the first caustic crossing by adopting more
aggressive observational strategies, the detection rate can be improved into
∼90.Comment: total 6 pages, including 5 Figures and no Table, submitted to MNRA