  Context. The ability to automatically select scientifically-important
transient events from an alert stream of many such events, and to conduct
follow-up observations in response, will become increasingly important in
astronomy. With wide-angle time domain surveys pushing to fainter limiting
magnitudes, the capability to follow-up on transient alerts far exceeds our
follow-up telescope resources, and effective target prioritization becomes
essential. The RoboNet-II microlensing program is a pathfinder project which
has developed an automated target selection process (RoboTAP) for gravitational
microlensing events which are observed in real-time using the Las Cumbres
Observatory telescope network. Aims. Follow-up telescopes typically have a much
smaller field-of-view compared to surveys, therefore the most promising
microlens- ing events must be automatically selected at any given time from an
annual sample exceeding 2000 events. The main challenge is to select between
events with a high planet detection sensitivity, aiming at the detection of
many planets and characterizing planetary anomalies. Methods. Our target
selection algorithm is a hybrid system based on estimates of the planet
detection zones around a microlens. It follows automatic anomaly alerts and
respects the expected survey coverage of specific events. Results. We introduce
the RoboTAP algorithm, whose purpose is to select and prioritize microlensing
events with high sensitivity to planetary companions. In this work, we
determine the planet sensitivity of the RoboNet follow-up program and provide a
working example of how a broker can be designed for a real-life transient
science program conducting follow-up observations in response to alerts,
exploring the issues that will confront similar programs being developed for
the Large Synoptic Survey Telescope (LSST) and other time domain surveys.
