The Optical Gravitational Lensing Experiment. Catalog of Microlensing Events in the Galactic Bulge

TL;DR

This paper presents a comprehensive catalog of 214 microlensing events detected in the Galactic bulge over three seasons, analyzing their distribution and implications for the structure of the Galactic bar.

Contribution

The paper provides the first large-scale catalog of microlensing events in the Galactic bulge, including binary events and spatial distribution analysis, based on extensive OGLE-II data.

Findings

Microlensing events are concentrated towards the Galactic bar.

The spatial distribution of events supports models of the Galactic bar.

The catalog includes 20 binary microlensing events, with 14 caustic crossings.

Abstract

We present the Catalog of microlensing events detected toward the Galactic bulge in three observing seasons, 1997--1999, during the OGLE-II microlensing survey. The search for microlensing events was performed using a database of about 4*10^9 photometric measurements of about 20.5 million stars from the Galactic bulge. The Catalog comprises 214 cases of microlensing events found in the fields covering about 11 square degrees on the sky and distributed in different parts of the Galactic bulge. The sample includes 20 binary microlensing events, 14 of them are caustic crossing. In one case a double star is likely lensed. We present distribution of the basic parameters of microlensing events and show preliminary rate of microlensing in different regions of the Galactic bulge. The latter reveals clear dependence on the Galactic coordinates. The dependence on 'l' indicates that the majority of lenses toward the Galactic bulge are located in the Galactic bar. Models of the Galactic bar seem to reasonably predict the observed spatial distribution of microlensing events in the Galactic bulge. All data presented in the Catalog and photometry of all events are available from the OGLE Internet archive.