{
  "bibcode": "2013GCN.15330....1R",
  "body": "A. Rau (MPE Garching), T. Kruehler (ESO), J. Greiner (MPE Garching)\nreport for the GROND team:\n\nWe observed the optical afterglow candidate iPTF13dsw of the Fermi-GBM \ntrigger 403206457 (Kasliwal et al. 2013, GCN 15324; Xu et al. 2013, \nGCN 15325; Perley et al. 2013, GCN 15327; Sudilovsky et al. 2013, GCN 15328)\nusing ESO/VLT UT3 equipped with the X-shooter spectrograph. The observations\nstarted on 2013-10-13 at 03:59 UT. A total exposure of 5x900 s was obtained, \ncovering the spectral range from ~3000 AA to ~24000 AA.\n\nIn the spectrum, we identify several very weak absorption features\nwhich we interpret as absorption from FeII, MgII and MgI at a common\nredshift of z = 1.874. This redshift is consistent with flux being\ndetected down to ~3200 AA, and a broad absorption feature around\n3400 AA corresponding to Lyman\\alpha. The combined evidence of fading, \npowerlaw slope SED and redshift suggests iPTF13dsw to be the optical \nafterglow of GRB 131011A.\n\nWe thank the Paranal staff for expert support, in particular Andrea\nMehner,  Christophe Martayan, Julio Navarrete, Felipe Gaete, L.\nSchmidtobreick, and A. Smette.",
  "circularId": 15330,
  "createdOn": 1381660024000,
  "email": "jcg@mpe.mpg.de",
  "subject": "iPTF 13dsw/Fermi403206457: X-Shooter redshift",
  "submitter": "Jochen Greiner at MPI  <jcg@mpe.mpg.de>"
}