ANOMALY ALERT: Multiple Lens Microlensing in MB-98-42

First posted: 27-Aug-1998
Last update: 16-Sep-1998

The PLANET collaboration has detected an anomalous decline of 1.7mag in the event MACHO 98-BLG-42 on August 25 between 18:00 and 23:30 UT. This decline followed a much slower, steady rise in brightness of 1.3mag in the three days following the MACHO normal microlensing alert on August 22. The lightcurve is inconsistent with point source point lens microlensing. Read the PLANET electronic anomaly alert here.

Event:                  MB-98-42
RA (J2000):         18:05:12.6
Dec (J2000):     -28:05:47

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.

September 3 update: PLANET photometry indicates that the event MACHO 98-BLG-42 is likely to be the result of binary lensing with finite source effects. Lightcurve is now falling smoothly and slowly.

September 16 update: PLANET photometry indicates that the event is now near its baseline magnitude.

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