{
  "bibcode": "2008GCN..7414....1G",
  "body": "P. Garnavich (Notre Dame), J. L. Prieto, R. Pogge (OSU) report:\n\nBeginning March 12.48 (UT), we again observed the position of\nGRB 080310 (Chornock et al. GCN 7381; Cummings et al., GCN 7382)\nwith the Large Binocular Telescope and LBC red and blue cameras.\nThe seeing was 0.7 arcsec in the r-Sloan filter.\n\nThe brightness of the afterglow 2.12 days after the burst is measured\nto be r=21.67+/-0.05 mag, or only 0.3 mag fainter than the previous\nnight. This corresponds to a power-law decay index of only 0.42\nand confirms the slowing in the decay rate noted in GCN 7409.\n\nIt is unlikely that the slow fade is due to contamination from\na host galaxy or a galaxy along the line of sight. To explain the\nobserved decay rate, a galaxy would have to contribute at a\nmagnitude near r=22.5, but nothing at this brightness is detected\nin the SDSS at the position of the afterglow. Also, the afterglow is\nconsistent with a point source in the LBT images obtained in good seeing.\n\nWe conclude that the shallow decay rate is intrinsic to the afterglow\nand this suggests either a continuing energy input or that the shock has\nencountered a change in density of the ambient medium. (We must note\nanother possibility: the afterglow is being gravitationally\nmicrolensed.)\n\nThe LBT is an international collaboration among institutions in the\nUnited States, Italy and Germany. The LBT Corporation partners are:\n*  The University of Arizona on behalf of the Arizona university system\n*  Istituto Nazionale di Astrofisica, Italy\n*  LBT Beteiligungsgesellschaft, Germany, representing the Max Planck\nSociety, the Astrophysical Institute Potsdam, and Heidelberg University\n*  The Ohio State University\n*  The Research Corporation, on behalf of The University of Notre Dame,\nUniversity of Minnesota and University of Virginia\n\nThis message may be cited.",
  "circularId": 7414,
  "createdOn": 1205331479000,
  "email": "pgarnavi@nd.edu",
  "subject": "GRB080310, unusual slow decay in the optical",
  "submitter": "Peter Garnavich at U of Notre Dame  <pgarnavi@nd.edu>",
  "eventId": "GRB 080310"
}