{
  "bibcode": "1999GCN...485....1S",
  "body": "Bradley E. Schaefer (Yale) reports:\n\n\"I have observed the afterglow of GRB991216 with the Yale 1m telescope on\nCTIO with B, R, and K filters last night and with B, V, R, I, and K\nfilters tonight.  The afterglow has faded by 1.15 +- 0.10 mag in the\nR-band between times 15.7 hours and 34.0 hours after the burst.  This\ncorresponds to a power-law decline of index -1.37 +- 0.12.\n\nThe images show the optical transient to not be a point source, but to\nhas some excess 'fuzziness' and extent.  This could well be the\nunderlying host galaxy.  If so, then this might have one of the brightest\nhosts known, leading to possibilities of sharply defining the local\nenvironment of the progenitor in conjunction with the accurate radio\nposition.  A bright host would also suggest a relatively small red shift,\nperhaps appropriate for one of BATSE's brightest bursts.\n\nLast night, I obtained substantial UBVRIK images covering \nthe preliminary RXTE error box.  At the end of this time, the RXTE\nreported a revised error box that was just outside my FOV.  By this\ntime, the position was at airmass of 2.5, and I could only get one\nR-band, one B-band, and some K-band images.  With the late arrival of \nthe revised RXTE error box, it was up to observatories farther west to\nidentify the afterglow by its variability.  On the second night, I am in\nthe middle of taking BVRIK images in two batches (to allow interpolation\nto a common time).  Here is a listing of the YALO data for the first two\nnights which shows the afterglow source:\n\t1999 Dec 17  07:47 UT     R-band    10 minutes\t\n\t1999 Dec 17  07:58 UT     B-band    10 minutes\n\t1999 Dec 17  07:47 UT     K-band    19 x 1 minute\n\t1999 Dec 18  01:58 UT     K-band    30 x 1 minute\n\t1999 Dec 18  01:58 UT     I-band    5 minutes\n\t1999 Dec 18  02:05 UT     R-band    5 minutes\n\t1999 Dec 18  02:12 UT     V-band    10 minutes\n\t1999 Dec 18  02:23 UT     B-band    10 minutes\n\t1999 Dec 18 ~06:00 UT     K-band    30 x 1 minute\n\t1999 Dec 18 ~06:00 UT     I-band    5 minutes\n\t1999 Dec 18 ~06:00 UT     R-band    5 minutes\n\t1999 Dec 18 ~06:00 UT     V-band    10 minutes\n\t1999 Dec 18 ~06:00 UT     B-band    10 minutes\nPhotometric standards were obtained also, but these data have not been\nreduced yet.\"",
  "circularId": 485,
  "createdOn": 945495331000,
  "email": "schaefer@grb2.physics.yale.edu",
  "subject": "GRB991216 Optical and infrared observations of Beethoven Burst",
  "submitter": "Brad Schaefer at Yale U  <schaefer@grb2.physics.yale.edu>",
  "eventId": "GRB 991216"
}