{
  "bibcode": "2014GCN.16849....1V",
  "body": "K. Varela (MPE Garching), D. A. Kann, S. Klose (both TLS Tautenburg),\nand J. Greiner (MPE Garching) report on behalf of the GROND team:\n\nWe observed the field of the Fermi LAT-detected GRB 140928A (Fermi GBM\ntrigger 433592996; Desiante et al., GCN #16847) simultaneously in\ng'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the\n2.2m MPG telescope at ESO La Silla Observatory (Chile).\n\nObservations started at 08:43.51 UT on 2014-09-29, 22.23 hrs after the GRB\ntrigger. They were performed at an average seeing of 1\".5 and at an\naverage airmass of 1.2.\n\nWe detect a source inside the enhanced 1\".5 Swift-XRT error circle (Pagani\net al., GCN #16848), at\n\nRA  (J2000.0) =  02:54:47.72\nDEC (J2000.0) = -55:55:44.0\n\nwith an uncertainty of 0\".5 in each coordinate.\n\nBased on total exposures of 460 s in g'r'i'z' and 480 s in JHK, we measure\nthe following preliminary magnitudes and upper limits (AB magnitude\nsystem):\n\ng' = 21.3 +/- 0.1,\nr' = 20.8 +/- 0.1,\ni' = 20.7 +/- 0.1,\nz' = 20.4 +/- 0.1,\nJ  = 20.2 +/- 0.2,\nH  = 20.1 +/- 0.2, and\nK  > 18.8.\n\nWe propose this source to be the optical/NIR afterglow of GRB 140928A. At\npresent we cannot decide if the source is fading.\n\nGiven magnitudes are calibrated against GROND zeropoints as well as 2MASS\nfield stars and are not corrected for the expected Galactic foreground\nextinction corresponding to a reddening of E_(B-V) = 0.01 mag in the\ndirection of the burst (Schlegel et al. 1998).",
  "circularId": 16849,
  "createdOn": 1411983808000,
  "email": "kann@tls-tautenburg.de",
  "subject": "GRB 140928A: GROND Afterglow Candidate",
  "submitter": "Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>",
  "eventId": "GRB 140928A"
}