Second caustic crossing in the binary microlens

First posted: 1-June-1999
Last updated: 3-June-1999

Analysis of PLANET data taken on the night spanning 2-3 June indicates that the caustic crossing in the microlensing event OGLE-99-BLG-011 is now over. The OGLE collaboration previously alerted the possible binary nature of this event. Early on 1 June, PLANET reported a brightening that suggested a rise toward a second caustic crossing at JD=2451334 +/- 2. OGLE reported a steepening in the brightness of this event in its 1-2 June data, and this together with our own data from two sites on that night caused us to revise our estimate for the time of the crossing to JD=2451332.3 +/- 0.5. Just before this revised alert, the event was about 2 magnitudes above its OGLE-reported baseline of I=18.5. Recent PLANET data indicate that it has now dropped back down to nearly its baseline value.

Event: OGLE 1999-BUL-11
RA (J2000):    18:05:29.59
Dec (J2000):   -27:59:14.4

Observations, both photometric and spectrographic are encouraged. Finding charts and future update information can be found on the PLANET web page at:

OGLE information on this event can be found at the OGLE alert web page at:

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