{
  "bibcode": "2012GCN.13542....1K",
  "body": "D. A. Kann, S. Klose (both TLS Tautenburg), and J. Greiner (MPE Garching)\nreport on behalf of the GROND team:\n\nWe observed again the field of GRB 120728A (Swift trigger 529021; Cummings\net al., GCN 13525) simultaneously in g'r'i'z'JHKs with GROND (Greiner et al.\n2008, PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla\nObservatory (Chile).\n\nCompared to our first epoch (Kann et al., GCN 13526), seeing conditions\nsignificantly improved to 1\".5 in the r' band. We obtained 7 minutes of\noptical observations and 12 minutes of NIR observations centered 1.035 days\nafter the GRB. We achieve limiting magnitudes which are 0.5 mag deeper in\nall optical bands compared to our first epoch, but shallower in the NIR.\n\nThe enhanced Swift-XRT position (Osborne et al., GCN 13528) does not include\nthe bright DSS source in the south-east anymore, but still overlaps with the\ntwo northern sources (Kann et al., GCN 13526). Upon close inspection, the\neastern source is also detected in the DSS, whereas the western source is\nnot. This source is furthermore not present anymore in our second epoch,\nwhich we confirm by image subtraction.\n\nWe therefore propose this source to be the optical afterglow of GRB 120728A,\nand derive a position:\n\nRA  (J2000) =  09:08:22.62,\nDEC (J2000) = -54:26:14.5\n\nwith an error of 0\".8.\n\nThe preliminary magnitude is r' = 20.80 +/- 0.16 (statistical) +/- 0.27\n(systematic) against the USNO-B1.0 catalog in the first epoch, 0.0377 days\nafter the GRB.",
  "circularId": 13542,
  "createdOn": 1343642983000,
  "email": "kann@tls-tautenburg.de",
  "subject": "GRB 120728A: GROND Afterglow discovery",
  "submitter": "Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>",
  "eventId": "GRB 120728A"
}