Identifying the Location in the Host Galaxy of the Short GRB 111117A   with the Chandra Sub-arcsecond Position
  We present our successful Chandra program designed to identify, with sub-arcsecond accuracy, the X-ray afterglow of the short GRB 111117A, which was discovered by Swift and Fermi. Thanks to our rapid target of opportunity request, Chandra clearly detected the X-ray afterglow, though no optical afterglow was found in deep optical observations. The host galaxy was clearly detected in the optical and near-infrared band, with the best photometric redshift of z=1.31_{-0.23}^{+0.46} (90% confidence), making it one of the highest known short GRB redshifts. Furthermore, we see an offset of 1.0 +- 0.2 arcseconds, which corresponds to 8.4 +- 1.7 kpc, between the host and the afterglow position. We discuss the importance of using Chandra for obtaining sub-arcsecond X-ray localizations of short GRB afterglows to study GRB environments. 
T. Sakamoto, E. Troja, K. Aoki, S. Guiriec, M. Im, G. Leloudas, D.   Malesani, A. Melandri, A. de Ugarte Postigo, Y. Urata, ...
astro-ph.HE