{
  "bibcode": "2009GCN..9469....1S",
  "body": "P. Schady (MSSL-UCL) and J. R. Cummings (NASA/UMBC) report on behalf of \nthe Swift/UVOT team:\n\nThe Swift/UVOT observed the field of GRB 090531B starting 3924 s after the \nBAT trigger (Cummings et al., GCN Circ. 9461), once the GRB came out of \nEarth limb observing constraint. No optical afterglow is detected in any \nof the UVOT exposures at the position of the X-ray afterglow (Sbarufatti \net al., GCN Circ. 9463), with the following three-sigma upper limits:\n\nFilter  T_mid(s)  Exp(s)   3-sig Mag UL\n\nwhite    3934      74      > 20.52\nv        4105      98      > 19.08\nb        4926      98      > 20.06\nu        4721      98      > 19.74\nuvw1     4515      98      > 19.65\nuvm2     4310      98      > 19.32\nuvw2     5336      98      > 19.61\n\nThe values quoted above are not corrected for the large Galactic \nextinction due to the reddening of E(B-V)=1.12 in the direction of the \nburst (Schlegel et al. 1998). The photometry is on the UVOT photometric \nsystem described in Poole et al. (2008, MNRAS, 383, 627).",
  "circularId": 9469,
  "createdOn": 1243850802000,
  "email": "ps@mssl.ucl.ac.uk",
  "subject": "GRB 090531B: Swift/UVOT Upper Limits",
  "submitter": "Patricia Schady at MSSL/Swift  <ps@mssl.ucl.ac.uk>",
  "eventId": "GRB 090531B"
}