T. Sakamoto, E. Troja, K. Aoki, S. Guiriec, M. Im, G. Leloudas, D. Malesani, A. Melandri, A. de Ugarte Postigo, Y. Urata, D. Xu, P. D'Avanzo, J. Gorosabel, Y. Jeon, R. Sanchez-Ramirez, M. I. Andersen, J. Bai, S. D. Barthelmy, M. S. Briggs, S. Foley, A. S. Fruchter, J. P. U. Fynbo, N. Gehrels, K. Huang, M. Jang, N. Kawai, H. Korhonen, J. Mao, J. P. Norris, R. D. Preece, J. L. Racusin, C. C. Thone, K. Vida, X. Zhao
We present our successful program using Chandra for identifying the X-ray afterglow with sub-arcsecond accuracy for the short GRB 111117A discovered by Swift and Fermi. Thanks to our rapid target of opportunity request, Chandra clearly detected the X-ray afterglow, whereas no optical afterglow was found in deep optical observations. Instead, we clearly detect the host galaxy in optical and also in near-infrared bands. We found that the best fit photometric redshift of the host is $z=1.31_{-0.23}^{+0.46}$ (90% confidence), making it one of the highest redshift short GRBs. Furthermore, we see an offset of $1.0 \pm 0.2$ arcseconds, which corresponds to $8.4 \pm 1.7$ kpc assuming z=1.31, between the host and the afterglow position. We discuss the importance of using Chandra for obtaining sub-arcsecond localization of the afterglow in X-rays for short GRBs to study GRB environments in great detail.
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http://arxiv.org/abs/1205.6774
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