[vsnet-alert 4246] Non-standard event OGLE-1999-BUL-19

[OGLE account <ogle@astrouw.edu.pl>]

BINARY NON-CAUSTIC CROSSING MICROLENS / BINARY SOURCE STAR / VARIABLE STAR ?

First observations of the OGLE-1999-BUL-19 microlensing event candidate 
collected during the new 2000 observing season at the Las Campanas
Observatory indicate that the candidate which was announced last year as
a low magnification, long t_0 event is apparently undergoing the second
brightening episode. The brightening is also consistent with the
microlensing light curve and it is much more prominent. Current
magnification is about 4 and the preliminary fit predicts A_max around 8.

The possible microlensing interpretations of the observed brightening
are:

- binary microlensing event which does not cross caustics.
- binary source star.

The third and least attractive possibility is that the object is a
strange variable star.

We encourage to follow-up observations.

OGLE-1999-BUL-19

Field          BUL_SC40
StarNo         434222
RA(J2000.0)    17:51:10.76
Dec(J2000.0)   -33:03:44.1
Remarks        

Very preliminary parameters of the second brightening:

  Tmax   2451624.789     5.851
  tau        136.044     8.105
  Amax         8.347     4.452
  Dmag         2.304     0.579
  I0          16.019     0.003

Finding charts, light curve plots, photometric data (updated regularly)
can be found in:
 
http://vsnet.astrouw.edu.pl/~ogle/ogle2/ews/1999/bul-19.html
http://vsnet.astrouw.edu.pl/ogle/ogle2/ews/1999/bul-19.tar.gz
 
regards, OGLE team.

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