{
  "bibcode": "2014GCN.16926....1K",
  "body": "D. A. Kann, A. Nicuesa Guelbenzu (both TLS Tautenburg), and J. Greiner\n(MPE Garching)  report on behalf of the GROND team:\n\nWe observed the field of GRB 141017A (Swift trigger 615672; Marshall et\nal., GCN #16919) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.\n2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at La Silla\nObservatory (Chile).\n\nObservations started at 02:50 UT on 18 October 2014, around 8.5 hours\nafter the GRB trigger. They were performed at an average seeing of 1\".7\nand at an average airmass of 1.9.\n\nBased on images with exposure times of 4130 s in g'r'i'z' (centered 0.459\ndays after the GRB) and 4800 s in JHK (centered 0.426 days after the GRB),\nwe detect a source within the Swift-XRT error circle reported by Goad et\nal. (GCN #16921) at position\n\nRA (J2000) = 06:14:31.28\nDec. (J2000) = -58:34:56.5\n\nwith an error of 0\".5 and the following 3-sigma AB magnitudes:\n\ng' = 24.3 +/- 0.2 mag,\nr' = 23.6 +/- 0.2 mag,\ni' = 23.4 +/- 0.2 mag,\nz' = 23.2 +/- 0.3 mag,\nJ > 22.0 mag,\nH > 21.4 mag, and\nK > 20.3 mag.\n\nThe object has faded strongly compared to the early UVOT detection (Oates\net al., GCN #16924) and the Zadko Gingin detection (Klotz et al., GCN\n#16920), confirming it as the afterglow. At this time, we cannot conclude\nif this object might already be the host galaxy of GRB 141017A. Comparison\nwith an epoch taken 75 minutes earlier at lower S/N shows no significant\nevidence for fading, but the spectrum is well-described by a spectral\nslope with beta = 1 and a possible drop-out in g' (redshift z > 2.2).\n\nGiven magnitudes are derived based on calibrating the images against GROND\nzeropoints (g'r'i'z') and 2MASS field stars (JHK) and are not corrected\nfor the Galactic foreground extinction corresponding to a reddening of\nE_(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998).",
  "circularId": 16926,
  "createdOn": 1413723431000,
  "email": "kann@tls-tautenburg.de",
  "subject": "GRB 141017A: GROND Afterglow Confirmation",
  "submitter": "Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>",
  "eventId": "GRB 141017A"
}