The PLANET collaboration has detected an anomaly in the on-going
microlensing event MB-97-28 (MACHO 97-BLG-28). After a smooth rise,
the source star exhibited rapid and dramatic departures from
a simple point source-point lens model.
The anomaly is suggestive of caustic structure due
to a multiple lens crossing an extended source
at JD - 2450449.0 = 165.5 +/- 0.1 days, at which
time the source was measured to be magnified by A ~ 13.
Continued PLANET observations indicate that
as of JD - 2450449.0 = 166.9, the event has fallen to A ~ 4, giving
it an approximate R magnitude of 15.4.
The anomaly at JD - 2450449.0 = 165.5 appears to be over, but
future behavior remains uncertain.
PLANET has detected evidence for source resolution effects at the crossing.
RA (J2000): 18:00:33.8
Dec (J2000) -28:01:10
Additional observations, both photometric and spectrographic, are encouraged. Finding charts with PLANET-selected reference stars and updated information for this event can be found on this PLANET web site.