{
  "bibcode": "2013GCN.15158....1S",
  "body": "V. Sudilovsky, M. Tanga, and J. Greiner\n(all MPE Garching) report on behalf of the GROND team:\n\nWe observed the field of GRB 130831B (Swift trigger 568855;\nMalesani et al. 2013, GCN #15141) simultaneously in g'r'i'z'JHK with\nGROND (Greiner et al. 2008, PASP 120, 405) mounted at the\n2.2 m MPG/ESO telescope at La Silla Observatory (Chile).\n\nObservations started at 23:22 UT on 31 Aug. 2013, 10 hours after the\nGRB trigger. They were performed at an average seeing of 2.2\" and at\nan average airmass of 2.2.\n\nBased on five co-added images with individual exposures of 6 min in\ng'r'i'z' and 4 min exposure in JHK, we do not detect a source within the\n3.6 arcsec Swift-XRT error circle reported by Malesani et al.\n(2013; GCN #15141) down to (all in the AB system)\n\ng' > 23.4,\nr' > 23.2,\ni' > 22.6,\nz' > 22.3,\nJ > 20.8,\nH > 20.2, and\nK > 19.6\n\nThe given limits are derived based on calibrating the images against\nGROND zeropoints and 2MASS field stars and are not corrected for the\nGalactic foreground extinction corresponding to a reddening of\nE_(B-V)= 0.08 in the direction of the burst (Schlegel et al. 1998).",
  "circularId": 15158,
  "createdOn": 1378048112000,
  "email": "vsudilov@mpe.mpg.de",
  "subject": "GRB 130831B: GROND upper limits",
  "submitter": "Vladimir Sudilovsky at MPE  <vsudilov@mpe.mpg.de>",
  "eventId": "GRB 130831B"
}