{
  "bibcode": "2003GCN..2110....1H",
  "body": "A. Henden (USRA/USNO, Flagstaff), B. Canzian (USNO),\nA. Zeh, S. Klose (Thueringer Landessternwarte Tautenburg),\n\non behalf of the FUN and another collaboration\n\nreport:\n\n\nUSNO Flagstaff has been observing the optical transient of GRB 030329\nstarting 0.65 days after the burst with high photometric accuracy. A\nplot of the BVRcIc data obtained during the first 8 days after the\nburst reveals short-term (during a night) and long-term (over days)\ncolor fluctuations. In particular, the USNO data reveal a broad bump\nin the B-Ic color of the  optical transient around day 5 when the\nafterglow shows an excess of red light compared to the earlier light\ncurve. Before the occurrence of this bump the optical transient\nreddened continuously but slowly.\n\nBetween day 5 and 7 the data reveal also an increase in the B-Rc color\nbut a decline of the V-Ic and Rc-Ic colors. On day 8, however, this\ntrend has stopped and the optical transient was considerably redder in\nall colors (B-V, V-Rc, Rc-Ic). More precisely, the optical transient\nwas redder than ever before. Based on the USNO data alone one cannot\ndecide what the reason for this color evolution is (emission lines\nfrom the underlying host galaxy, a dust echo, broad-band supernova\nfeatures, intrinsic afterglow physics, etc.). If it is a supernova\n(Matheson et al., GCN 2107; Bersier et al., GCN 2109) then the color\nchanges much more rapidly than predicted by the simplest model (Zeh et\nal., GCN 2081).",
  "circularId": 2110,
  "createdOn": 1049715370000,
  "email": "klose@tls-tautenburg.de",
  "subject": "GRB 030329, color evolution",
  "submitter": "Sylvio Klose at TLS Tautenburg  <klose@tls-tautenburg.de>",
  "eventId": "GRB 030329"
}