{
  "bibcode": "2000GCN...517....1S",
  "body": "Bradley E. Schaefer (Yale) reports:\n\n\"I have obtained deep R-band images with the 3.5m WIYN telescope on Kitt\nPeak starting on January 6, 2000 at 04:35 UT.  The images had 0.6-0.8\" \nFWHM seeing and used the Harris-R filter on the Mini-Mosaic camera.  After\nstandard processing, IRAF APPHOT photometry (with 0.6\" radius aperture)\nwas used.  The only calibrated star which was unsaturated in my images is\nStar B, with R=19.45+-0.03 (Dolan et al. GCN 486).  The optical transient\nis still visible with a SNR~7 within 0.3\" of the radio position.  My two\nmeasures of the optical transient magnitude are R=24.20+-0.15 and\nR=24.24+-0.20.  \n\nThese observations were taken around the time when a possible underlying\nsupernova would be at peak.  However, if the red shift is 1.02 or greater\n(Vreeswijk et al. GCN 496) and the supernova is like SN1998bw, then the\nsupernova light should be fainter than R~25.0 (Bloom et al. 1999, Nature,\n401, 453).\n\nAn extrapolation of the afterglow light curve from the first few days of\nthe burst gives either 23.45+-0.14 (Garnavich et al. GCN 495;\nindex=-1.23+-0.05) or 23.66+-0.25 (Jensen et al. GCN 498;\nindex=-1.17+-0.10).  Thus, my combined magnitude (R=24.21+-0.12) is\ntwo-sigma fainter than the faintest of these extrapolations.  (A similar\nresult was found by Djorgovski et al. [GCN 510] for an observation on\nDecember 29, 1999.)  An index of -1.40+- 0.06 since several days after the\nburst is needed to satisfy my observed magnitudes.  It is possible that\nthis is a break in the afterglow light curve (like for GRB990510) due\nperhaps to the evolution of a jet.\"",
  "circularId": 517,
  "createdOn": 947294811000,
  "email": "schaefer@grb2.physics.yale.edu",
  "subject": "GRB991216 late optical observation",
  "submitter": "Brad Schaefer at Yale U  <schaefer@grb2.physics.yale.edu>",
  "eventId": "GRB 991216"
}