Variability-selected QSO candidates in OGLE-II Galactic Bulge fields

We present 97 QSO candidates in 48 Galactic Bulge fields of the Optical Gravitational Lensing Experiment II (OGLE-II) covering ∼ 11 square degrees, which are selected via their variability. We extend light curves of variable objects which were detected in 3-year baseline in the OGLE-II variable star catalog to 4th year. We search for objects which are faint (16 < I0 < 18.5) and slowly variable during 4 years in this catalog by using the variogram/structure function. Finding the QSOs in such stellar-crowded and high extinction fields is challenging, but should be useful for the astrometric reference frame. Spectroscopic follow-up observations are required to confirm these QSO candidates. Follow-up observations are being prepared for four of these fields (BUL SC1, 2, 32 and 45). Follow-up observations for other fields are strongly encouraged. The complete list and light curves of all 97 candidates are available in electronic format at http://www.astro.princeton.edu∼sumi/QSO-OGLEII/.