{
  "bibcode": "2007GCN..6389....1T",
  "body": "Christina C. Thoene, Johan P. U. Fynbo (DARK) and Andrew Williams (Perth\nObservatory) report:\n\nWe observed the OT of GRB 070508 (GCN 6383, Grupe et al.) with DFOSC at\nthe Danish 1.54m on La Silla in V, R and I band, starting at May 8, 08:15\nUT (3.8h after the burst) until sunrise.\nThe burst is clearly detected in 300s exposures in R and I band, but\nundetected in 600s V band images. At a mean time of 4.1h after the burst,\nwe measure the following magnitudes (based on preliminary photometric\nzeropoints):\n\nI = 20.5 +- 0.2\nR = 21.5 +- 0.2\nV > 22.9\n\nwhich indicates a red color. The nondetection in V together with the red\ncolor might suggest a redshift of z > 3.5.\nThe afterglow is clearly fading between 3.8h and 5.8h after the burst,\nshowing a rather steep temporal slope in the I band of alpha = 3.1 +-0.6.\n\n[GCN OPS NOTE(08may07): Per author's request, the word 'limit'\nwas added to the Subject line.]",
  "circularId": 6389,
  "createdOn": 1178631222000,
  "email": "cthoene@astro.ku.dk",
  "subject": "GRB 070508: Multicolor optical observations and possible redshift limit",
  "submitter": "Christina Thoene at Niels Bohr Institute,DARK Cosmo Ctr  <cthoene@astro.ku.dk>",
  "eventId": "GRB 070508"
}