{
  "bibcode": "2014GCN.16724....1S",
  "body": "S. Schmidl (TLS Tautenburg), K. Varela (MPE Garching), D. A. Kann (TLS\nTautenburg) and J. Greiner (MPE Garching) report on behalf of the GROND\nteam:\n\nWe observed the field of GRB 140819A (Fermi trigger 430148973; optical\ncandidate: Lipunov et al., GCN #16720) simultaneously in g'r'i'z'JHK with\nGROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPG\ntelescope at ESO La Silla Observatory (Chile).\n\nObservations started on August 19, 2014, at 23:42 UT, 9.9 hrs after the\nGRB trigger. They were performed at an average seeing of 1.0\" and at an\naverage airmass of 1.1.\n\nWe do not detect a source at the postion of the afterglow candidate\nreported by Lipunov et al. (GCN #16720).\n\nBased on a total exposure of 25 minutes in g'r'i'z'and 20 minutes in JHK,\nat a midtime of 0.42 days after the burst, we measure the following\npreliminary upper limits (AB magnitudes system):\n\ng' > 25.0,\nr' > 25.0,\ni' > 24.1,\nz' > 23.6,\nJ  > 20.9,\nH  > 20.7, and\nK  > 18.8.\n\nThese derived upper limits are significantly deeper than those reported\nbeforehand (Espartero et al., GCN #16772, Dichiara et al., GCN #16773).\n\nThe decay slope between the 10th magnitude detection at a minute after the\nGRB and r' > 25 mag at 10 hours implies a decay slope > 2. Such a steep\nslope over a prolonged period of time is unlikely. Note that if the\ntransient is not seen already in the second image taken by MASTER, an even\nsteeper slope is implied (assuming a magnitude limit of 12.6 for the\nimage).\n\nWe therefore propose the optical transient is unassociated with the GRB,\nand may be due to, e.g., a glint off a tumbling object in near Earth\norbit.\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) = 0.58 mag\nin the direction of the burst (Schlegel et al. 1998).",
  "circularId": 16724,
  "createdOn": 1408498311000,
  "email": "schmidl@tls-tautenburg.de",
  "subject": "GRB140819A: Deep GROND Upper Limits",
  "submitter": "Sebastian Schmidl at TLS Tautenburg  <schmidl@tls-tautenburg.de>",
  "eventId": "GRB 140819A"
}