{
  "bibcode": "2012GCN.13551....1D",
  "body": "P. D'Avanzo, A. Melandri (INAF-OAB), I. Steele, C.G. Mundell (LJMU),  \nE. Palazzi (INAF-IASFBo) report, on behalf of larger collaborations:\n\nWe observed the optical counterpart of GRB 120729A (Ukwatta et al.,  \nGCN 13530; Virgili et al., GCN 13531; Oates et al., GCN 13539; Wren et  \nal., GCN 13545) with the 2-m Faulkes Telescope North (FTN), the 2-m  \nLiverpool Telescope (LT) and with the Italian 3.6m Telescopio  \nNazionale Galileo (TNG). Early time observations were carried out from  \n4.6 min to 2.1 hours after the burst with the FTN, while a later  \nobservation epoch was taken at a mid time of about 14.5 hours after  \nthe burst with the LT and the TNG.\n\n From a preliminary analysis the overall R-band light curve can be  \ndescribed by an initial power-law decay with an index of alpha1=1.0  \nthat breaks around t-t0=6000 s to a steeper decay with alpha2=1.8. The  \nearly time decay is consistent with the report of Wren et al. (GCN  \n13545).\n\nThe last detection was obtained with the TNG at a level of R ~ 23.3  \nmag (15.1 hours post burst) consistent with the marginal detections  \nobtained with LT SDSS-r filter (image acquired ~13.6 hours after the  \nburst). These late time values fall slightly below the best broken  \npower-law fit described above, suggesting that the post-break decay  \nindex might be steeper than 2.\n\nWe note that the reported X-ray afterglow decay (Maselli et al., GCN  \n13541) shows a similar behaviour and that this may be indicative of an  \nachromatic break in the afterglow light curve.\n\nWe thank the TNG staff for performing the ToO observations, in  \nparticular Massimo Cecconi.",
  "circularId": 13551,
  "createdOn": 1343732792000,
  "email": "andrea.melandri@brera.inaf.it",
  "subject": "GRB 120729A: break in the optical light curve",
  "submitter": "Andrea Melandri at INAF-OAB  <andrea.melandri@brera.inaf.it>",
  "eventId": "GRB 120729A"
}