  The microlensing event OGLE-2008-BLG-510 is characterised by an evident
asymmetric shape of the peak, promptly detected by the ARTEMiS system in real
time. The skewness of the light curve appears to be compatible both with
binary-lens and binary-source models, including the possibility that the lens
system consists of an M dwarf orbited by a brown dwarf. The detection of this
microlensing anomaly and our analysis demonstrates that: 1) automated real-time
detection of weak microlensing anomalies with immediate feedback is feasible,
efficient, and sensitive, 2) rather common weak features intrinsically come
with ambiguities that are not easily resolved from photometric light curves, 3)
a modelling approach that finds all features of parameter space rather than
just the `favourite model' is required, and 4) the data quality is most
crucial, where systematics can be confused with real features, in particular
small higher-order effects such as orbital motion signatures. It moreover
becomes apparent that events with weak signatures are a silver mine for
statistical studies, although not easy to exploit. Clues about the apparent
paucity of both brown-dwarf companions and binary-source microlensing events
might hide here.
