The Galactic bulge source MOA-2010-BLG-523S exhibited short-term deviations from a standard microlensing light curve near the peak of an A max ∼ 265 high-magnification microlensing event. The deviations originally seemed consistent with expectations for a planetary companion to the principal lens. We combine long-term photometric monitoring with a previously published high-resolution spectrum taken near peak to demonstrate that this is an RS CVn variable, so that planetary microlensing is not required to explain the light-curve deviations. This is the first spectroscopically confirmed RS CVn star discovered in the Galactic bulge. © 2013. The American Astronomical Society. All rights reserved..
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Gould, A., Yee, J., Bond, I., Udalski, A., Han, C., Jørgensen, U., Greenhill, J., Tsapras, Y., Pinsonneault, M., Bensby, T., Allen, W., Almeida, L., Bos, M., Christie, G., Depoy, D., Dong, S., Gaudi, B., Hung, L., Jablonski, F., Lee, C., McCormick, J., Moorhouse, D., Muñoz, J., Natusch, T., Nola, M., Pogge, R., Skowron, J., Thornley, G., Abe, F., Bennett, D., Botzler, C., Chote, P., & Freeman, M. (2013). MOA-2010-BLG-523: "failed planet" = RS CVn STAR. Astrophysical Journal, 763 (2) https://doi.org/10.1088/0004-637X/763/2/141