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

T. Sumi·P. R. Wozniak·L. Eyer·A. Dobrzycki·A. Udalski·M. K. Szymanski·M. Kubiak·G. Pietrzynski·I. Soszynski·K. Zebrun·O. Szewczyk·L. Wyrzykowski
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Abstract

We present 97 QSO candidates in 48 Galactic Bulge fields of the Optical Gravitational Lensing Experiment II (OGLE-II) covering about 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<I_0<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/.

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T. Sumi, P. R. Wozniak, L. Eyer, A. Dobrzycki, A. Udalski, M. K. Szymanski, M. Kubiak, G. Pietrzynski, I. Soszynski, K. Zebrun, O. Szewczyk, L. Wyrzykowski. 2004-10-02. Variability-selected QSO candidates in OGLE-II Galactic Bulge fields. https://doi.org/10.1111/j.1365-2966.2004.08453.x

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