{
  "bibcode": "2013GCN.15247....1S",
  "body": "V. Sudilovsky (MPE Garching), D.A. Kann, and J. Greiner\n(all MPE Garching) report on behalf of the GROND team:\n\nWe observed the field of GRB 130925A (Lien et al., GCN #15246)\nsimultaneously in g'r'i'z'JHKs with GROND (Greiner et al. 2008,\nPASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla\nObservatory (Chile).\n\nThe first epoch observation started at 04:18:52 UT on 25 Sept 2013,\n7 minutes after the GRB trigger. They were performed at an average\nseeing of 0.7\" and at an average airmass of 1.3. We do not find any\nsources within the revised 3\".6 Swift XRT error circle. However, we do\nfind an uncataloged red source 2\" east of the error circle at position:\n\nRA  (J2000.0) = 02:44:42.96 = 41.1790\nDec. (J2000.0) = -26:09:11.16 = -26.1531\n\nwith an uncertainty of 0.3\" in each coordinate.\n\nBased on a total exposure of 4.4 minutes in g'r'i'z' and 4 minutes in\nJHK, we estimate preliminary magnitudes (all in AB) of\n\ng' > 21.5 mag,\nr' > 22 mag,\ni' = 21.8 � 0.1 mag,\nz' = 21.3 � 0.1 mag,\nJ = 19.6 � 0.1 mag,\nH = 18.6 � 0.1 mag, and\nK = 18.0 � 0.1 mag.\n\nThe source is seen to be brightening in the first images before\nfading strongly. We suggest this source to be the afterglow of GRB\n130925A.\n\nGiven magnitudes are calibrated against GROND zeropoints as well as\n2MASS field stars and are not corrected for the expected Galactic\nforeground extinction corresponding to a reddening of E_(B-V) = 0.02\nmag in the direction of the burst (Schlegel et al. 1998).",
  "circularId": 15247,
  "createdOn": 1380089122000,
  "email": "vsudilov@mpe.mpg.de",
  "subject": "GRB 130925A: GROND afterglow candidate",
  "submitter": "Vladimir Sudilovsky at MPE  <vsudilov@mpe.mpg.de>",
  "eventId": "GRB 130925A"
}