{
  "bibcode": "2012GCN.12878....1C",
  "body": "B. E. Cobb (GWU), reports:\n\nUsing the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained\noptical/IR imaging of the error region of GRB 120119A (GCN 12859,\nBeardmore et al.) over several epochs, starting ~0.6 hours post-burst.\nFor the first epoch, several dithered images were obtained in each filter,\nwith total summed exposure times of 180s in each of BRIJK and 120s in each\nof H and V.  For later epochs, total summed exposure times amounted to 15\nminutes in I and V and 12 minutes in J and K.\n\nAt a mid-exposure time of 2012-01-19 04:43 UT (0.64 hrs post-burst), the\nGRB afterglow (e.g. GCN 12859, Beardmore et al., GCN 12860, Morgan et\nal., GCN 12863, Schady et al.) is detected with the following magnitudes:\n\nB = 20.07 +/- 0.06\nV = 18.91 +/- 0.05\nR = 18.02 +/- 0.03\nI = 16.96 +/- 0.03\nJ = 15.14 +/- 0.05\nH = 14.02 +/- 0.06\nK = 12.89 +/- 0.10\n\nBetween about 0.6 hrs and 3 hrs post-burst, the GRB afterglow fades with a\ndecay rate of approximately alpha = 1.6 (where afterglow flux is\nproportional to t^-alpha).\n\ntime\npost-burst      I-band magnitude\n0.64 hrs        16.96 +/- 0.03\n1.71 hrs        18.52 +/- 0.03\n2.97 hrs        19.39 +/- 0.05\n\n(Optical photometry is calibrated against Landolt standard stars\nand IR photometry is calibrated against 2MASS stars in the field.)",
  "circularId": 12878,
  "createdOn": 1327002415000,
  "email": "bcobb@gwu.edu",
  "subject": "GRB 120119A: SMARTS optical/IR afterglow observations",
  "submitter": "Bethany Cobb at GWU  <bcobb@gwu.edu>",
  "eventId": "GRB 120119A"
}