{
  "bibcode": "2019GCN.25959....1S",
  "body": "P. Schady (Univ. of Bath), J. Balmer (MPE Garching), and A. Nicuesa Guelbenzu (TLS Tautenburg) report:\n\n\nWe observed the field of GRB 191004A (Swift trigger 927825; Cenko et al., GCN #25945) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).\n\n\nObservations started at 01:56 UT on 5th October, 7.8 hours after the GRB trigger. They were performed at an average seeing of 1.4\" and at an average airmass of 1.5.\n\n\nWe do not detect a source at the position of the Swift-XRT and MASTER afterglow (Osborne et al., GCN #25950; Lipunov et al., GCN #25944) down to the following 3-sigma limits (all AB magnitude):\n\n\ng' > 23.7 mag\nr' > 24.2 mag\ni' > 23.5 mag\nz' > 23.3 mag\nJ > 21.4 mag\nH > 20.4 mag\nK > 19.9 mag\n\n\nThe given limits are derived based on calibrating the images against Sky-Mapper and 2MASS field stars and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.01 in the direction of the burst (Schlafly & Finkbeiner 2011).\n\nWe acknowledge the excellent support from Regis Lachaume in La Silla in acquiring these observations.",
  "circularId": 25959,
  "createdOn": 1570357386000,
  "email": "p.schady@bath.ac.uk",
  "subject": "GRB 191004A: GROND Upper limits",
  "submitter": "Patricia Schady at Swift  <p.schady@bath.ac.uk>",
  "eventId": "GRB 191004A"
}