Anomalous high-magnification event MOA 2004-BLG-33 / OGLE 2004-BLG-367

Anomalous high-magnification event MOA 2004-BLG-33 / OGLE 2004-BLG-367

First posted on homepage: 24-Jun-2004
Moved to news archive: 29-Jun-2004

On 22-Jun, 16:36 UT, MOA issued an alert for the event MOA 2004-BLG-33 (also known as OGLE 2004-BLG-367), warning of extremely high magnification, with the peak due in 8 hours time. As announced in PLANET anomaly alert 2004 #8 (issued 24-Jun, 10:45 UT), subsequent data collected by MOA, OGLE, PLANET and MicroFUN revealed a peak at a magnitude I ∼ 12.5 near HJD=2453179.6 (June 23.1), corresponding to a magnification of more than 100. Later OGLE data and PLANET data from the Danish 1.54m telescope at ESO LaSilla (Chile) indicate a plateau at I ∼ 14.6. It was suggested that the event may rise to another peak and continuing dense monitoring will resolve its nature.

Instead of the suspected rise, further PLANET data taken at the Canopus 1m near Hobart (Tasmania, Australia) between HJD=2453181.06 (25-Jun, 16:05 UT) and 2453181.22 (24-Jun, 17:17 UT), showed a continuation of this slow decline, while data from the following night, taken between HJD=2453182.17 (25-Jun, 16:05 UT) and 2453182.29 (25-Jun, 18:58 UT) show a marked drop of 0.7 to 0.8 mag, and a change in slope to a faster decline, so that the lightcurve shows a 'shoulder' rather than two peaks. This has been reported in PLANET anomaly update 2004 #8-1 (issued 26-Jun, 4:00 UT).

Recent data from MOA, OGLE, and PLANET is shown on our regularly updated lightcurve.

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