POSSIBLE BINARY MICROLENSING Observations collected by OGLE during the last few nights at the Las Campanas Observatory indicate significant deviation of the OGLE-1999-BUL-42 microlensing event from single-source microlensing light curve. Deviation seems to be typical for causting crossing binary microlensing. It is very likely that the second caustic crossing will occur within a few next days. Follow up observations are strongly encouraged !!! OGLE-1999-BUL-42 Field BUL_SC33 StarNo 476067 RA(J2000.0) 18:05:38.68 Dec(J2000.0) -28:52:11.2 Remarks Possible caustic crossing binary event Finding charts, light curve plots, photometric data (updated regularly) can be found in: http://vsnet.astrouw.edu.pl/~ftp/ogle/ogle2/ews/bul-42.html http://vsnet.astrouw.edu.pl/ogle/ogle2/ews/1999/bul-42.tar.gz regards, OGLE team.