{
  "bibcode": "2019GCN.25992....1N",
  "body": "A. Nicuesa Guelbenzu (TLS Tautenburg) and P. Schady (Univ. of Bath)\nreport:\n\nWe observed the field of GRB 191011A (Swift trigger 928924; Laha et al.,\nGCN 25988) simultaneously in g'r'i'z'JHKs with GROND (Greiner et al. 2008,\nPASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla\nObservatory (Chile).\n\nObservations started at 04:38 UT on 2019-10-11, around 2 minutes after the\nGRB trigger and lasted for about 5 minutes. They were performed at an\naverage seeing of 1.14\" and at an average airmass of 1.1.\n\nWe detect the optical afterglow candidate reported by Laha et al. (GCN\n25988) and measure the following preliminary magnitudes and upper limits\n(AB magnitudes):\n\nr' = 19.52 +/- 0.1 mag,\ni' = 18.46 +/- 0.05 mag,\nz' = 18.62 +/- 0.1 mag,\nJ  = 17.89 +/- 0.1 mag,\nH  = 17.21 +/- 0.1 mag.\n\nThe optical afterglow is also visible in g' band.\n\nThe magnitudes are calibrated against GROND zeropoints and 2MASS field\nstars and are not corrected for the Galactic foreground extinction\ncorresponding to a reddening of E_(B-V)= 0.02 mag in the direction of the\nburst (Schlegel et al. 1998).\n\nWe acknowledge the excellent support from Regis Lachaume in La Silla\nin acquiring these observations.",
  "circularId": 25992,
  "createdOn": 1570775046000,
  "email": "ana@tls-tautenburg.de",
  "subject": "GRB 191011A: GROND Detection of the Optical/NIR afterglow",
  "submitter": "Ana Nicuesa at TLS Tautenburg  <ana@tls-tautenburg.de>",
  "eventId": "GRB 191011A"
}