The PLANET collaboration has detected an anomaly in the on-going microlensing event OGLE-1999-BUL-23. Previous anomalous behaviour had been alerted by the PLANET collaboration. Recent PLANET observations from Canopus (Tasmania) and Perth Observatories indicate the event has just undergone a second caustic crossing, peaking at approximately 19-Jun-1999 12:15 UT (=JD2451349.01). The event is currently at about A~4.3 and falling slowly. A caustic alert was issued.
Event: OB-99-023
RA (J2000): 18:07:45.14
Dec (J2000): -27:33:15.4
The baseline I magnitude reported by the OGLE team is 17.85.
PLANET continues to observe this event.
Caustic crossing events can be used to measure source resolution effects, which can allow the determination of the relative proper motion of the lens and, in special circumstances, the limb-darkening of the source star. High magnification events, are especially likely to betray the presence of possible planets orbiting the lens.
Finding charts and future updated information can be found on the PLANET web site at http://planet.iap.fr.
OGLE information on this event can be found at the OGLE alert web page at: http://www.astrouw.edu.pl/~ftp/ogle/ogle2/ews/bul-23.html.