Optical Gravitational Lensing Experiment

The Optical Gravitational Lensing Experiment or OGLE is a Polish astronomical project based at the University of Warsaw that is chiefly concerned with discovering dark matter using the microlensing technique. Since the project began in 1992, it has discovered several extrasolar planets as a side benefit. The project is led by Professor Andrzej Udalski, who is a co-author of the discovery of OGLE-2005-BLG-390Lb.

The main targets of the experiment are the Magellanic Clouds and the Galactic Bulge, because of the large number of intervening stars that can be used for microlensing during a stellar transit. Most of the observations have been taken at the Las Campanas Observatory in Chile. Cooperating institutions include Princeton University and the Carnegie Institution.

The three phases of the project had already been concluded, OGLE-I (1992–1995), OGLE-II (1996–2000), and OGLE-III (2001–2009). OGLE-I was the project pilot phase; for OGLE-II, a telescope was specially constructed, placed in Las Campanas Observatory and dedicated to the project. The 8-chip mosaic CCD camera was built in Poland and shipped to Chile. OGLE-III was primarily devoted to detecting gravitational microlensing events and transiting planets. As a byproduct of constant monitoring of hundreds of millions of stars, the largest catalogs of variable stars were constructed. The fields in four main directions where monitored during this phase: in the direction of the Galactic Bulge, the constellation Carina and toward both Large Magellanic Cloud and Small Magellanic Cloud. Also, first planets using the microlensing technique were detected during that phase. In 2010, following engineering work in 2009, the fourth phase, OGLE-IV, have been started using 32-chip mosaic CCD camera. The main goal for that phase is to increase the number of planetary detections using microlensing. The increased field of view of the new camera give the possibility for increased cadence of observations when keeping the monitored area of the sky at similar level.