{
  "bibcode": "2007GCN..7028....1B",
  "body": "A. A. Breeveld (MSSL/UCL) and M. Stroh (PSU) report on behalf of the \nSwift-UVOT team:\n\nThe Swift/UVOT observed the burst GRB 071031 (Stroh et al. GCN Circ. \n7020) starting with the finding chart exposure in white, 114 seconds \nafter the BAT trigger. The afterglow is detected at the UVOT position \ngiven in Stroh et al. (GCN Circ. 7020) in white, v and b until at least \n7000s after the trigger. It is barely detected in u and not at all in \nthe UV filters; this is consistent with the redshift of z=2.692 found by \nLedoux et al. (GCN Circ. 7023). The brightness apparently increases for \nthe first few hundred seconds and then fades with an estimated temporal \nslope in the v filter of alpha = 0.56.\n\nThe initial UVOT magnitudes and upper limits from single exposures or \nco-added exposures are as follows:\nFilter  Tstart(s)  Tstop(s)  Exp(s)  Mag\n\nwhite   114        213       99.8    19.88 � 0.14\n          715       724       9.8     19.3  � 0.3\n         867        966       99.8    19.41 � 0.1\n        6778       6977      199.8    20.67 � 0.18\nv       220        619      399.8    19.08 � 0.15\n         973       1219      246.2    18.5 � 0.13\n       11517      11816      299.8    19.93 � 0.32\nb       700        709        9.8    >18.77 (3 sigma UL)\n        6573       6772       199.8   20.25 � 0.23\nu       675        847        38.9   19.38 � 0.38\n        4933       6567       393.3   >20.82 (3 sigma UL)\nuvw1   651       16990      1317.7   >21.41 (3 sigma UL)\nuvm2   626       12782      1089.4   >21.23 (3 sigma UL)\nuvw2   730       11206      1118.4   >21.46 (3 sigma UL)\n\n\nThe values quoted above are not corrected for the expected Galactic\nextinction corresponding to a reddening of E_{B-V} = 0.012 mag in the\ndirection of the burst (Schlegel et al. 1998).",
  "circularId": 7028,
  "createdOn": 1193854256000,
  "email": "aad@mssl.ucl.ac.uk",
  "subject": "GRB 071031: Swift/UVOT detection of afterglow",
  "submitter": "Alice Breeveld at MSSL-UCL  <aad@mssl.ucl.ac.uk>",
  "eventId": "GRB 071031"
}