{
  "bibcode": "2013GCN.14325....1S",
  "body": "S. Schmidl (TLS Tautenburg), J. Elliott (MPE Garching), A. Nicuesa\nGuelbenzu (TLS Tautenburg), S. Klose (TLS Tautenburg), and J. Greiner\n(MPE Garching) report on behalf of the GROND team:\n\nWe observed the field of GRB 130315A (Swift trigger 551126; Evans et\nal., GCN 14311) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.\n2008, PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla\nObservatory (Chile).\n\nFirst-epoch observations started on March 15, 2013, at 23:51 UT, 11.1\nhrs after the GRB trigger. They were performed at an average seeing of\n0.\"7 and at an average airmass of 1.18. No evidence for a fading\nafterglow was found.\n\nSecond-epoch observations were executed the following night (38.4 hr\nafter the trigger) under slightly worse observing conditions. A\ncomparison with the first-epoch images reveales a fading source at the\nsouth-east border of the Swift/XRT error circle (Page et al., GCN 14317)\nat coordinates\n\nRA (J2000.0)  =  10:30:11.54\nDec (J2000.0) = -51:47:39.8\n\nwith an uncertainty of 0.\"5 in each coordinate.\n\nBased on a total exposure time of 1500 s in r'i'z' at a midtime of\n12.8 hrs after the burst, for this source we measure the following\npreliminary AB magnitudes:\n\nr' = 22.0 +/- 0.1,\ni' = 21.5 +/- 0.1,\nz' = 21.1 +/- 0.1.\n\nBetween both epochs this object faded by more than 1 magnitude, implying\na decay with alpha > 0.75.\n\nThe given magnitudes are calibrated against GROND zeropoints. The\nGalactic reddening along the line of sight is E(B-V)= 0.36 mag (Schlegel\net al. 1998).",
  "circularId": 14325,
  "createdOn": 1363543895000,
  "email": "schmidl@tls-tautenburg.de",
  "subject": "GRB 130315A: GROND afterglow candidate",
  "submitter": "Sebastian Schmidl at TLS Tautenburg  <schmidl@tls-tautenburg.de>",
  "eventId": "GRB 130315A"
}