{
  "bibcode": "2011GCN.12773....1M",
  "body": "A. Melandri (INAF-OAB), C. Guidorzi (U. Ferrara), C. G. Mundell (Liverpool JMU) \nand N. R. Tanvir (U. Leicester), on behalf of a large collaboration report:\n\n\"We observed the optical afterglow of GRB 111228A (Ukwatta et al., GCN \n12737) with the 2-m Liverpool Telescope, starting at 02:55 UT on 2011 December 29. We \ntook a sequence of images in Br'i' bands, with exposure time of 300s for each \nindividual frame.\n\nWe clearly detect the optical afterglow in all individual images. In \nstacked frames we find the following magnitudes for the OT:\n\nMid time from  Total Exp   Filter    Magnitude\ntrigger (hr)    (s)\n--------------------------------------------------\n12.08          4x300       r'        19.68 +- 0.06\n13.28          3x300       r'        19.89 +- 0.09\n12.54          5x300       i'        19.57 +- 0.05\n11.34          4x300       B         19.71 +- 0.08\n12.96          4x300       B         19.79 +- 0.11\n--------------------------------------------------\n\nThe magnitudes are calibrated against nearby SDSS-5 (r' and i' bands) and \nUSNO-B1.0 (B band) field stars and are not corrected for the Galactic \nextinction.\n\nThis message may be cited.\"",
  "circularId": 12773,
  "createdOn": 1325193260000,
  "email": "cgm@astro.livjm.ac.uk",
  "subject": "GRB 111228A: Liverpool Telescope Observations",
  "submitter": "Carole Mundell at ARI, JMU,Liverpool  <cgm@astro.livjm.ac.uk>",
  "eventId": "GRB 111228A"
}