{
  "bibcode": "2017GCN.21207....1S",
  "body": "M. H. Siegel (PSU) and K. L. Page (U. Leicester)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 170604A\n128 s after the BAT trigger (Page et al., GCN Circ. 21191).\nWe detect a fading afterglow consistent with the position given by XRT\n(Page et al., GCN Circ 21196) and ground-based optical detections\n(Izzy et al., GCN Circ 21197; Schady, GCN Circ. 21200; Mazaeva et al., \nGCN Circ 21203).\n\nThe preliminary UVOT position is:\n    RA  (J2000) =  22:50:37.52 = 342.65632 (deg.)\n    Dec (J2000) = -15:24:43.9  = -15.41220 (deg.)\nwith an estimated uncertainty of 0.1 arc sec. (radius, 90% confidence).\n\nPreliminary magnitudes and 3-sigma upper limits using the UVOT photometric system\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first\nfinding chart (FC) exposure and subsequent exposures are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)         Mag\n\nwhite (fc)         128          278          147          15.81+-0.03\nwhite             3968         5603          393          18.72+-0.06\nwhite            39053        39959          885          20.57+-0.18\nv                 4378         6013          393          18.94+-0.31\nv                34480        44756         1268         >19.89\nb                 3763         5398          393          19.26+-0.15\nb                38141        39048          885         >20.86\nu (fc)             287          429          279          15.70+-0.03\nu                 4993         5193          196          18.51+-0.16\nu                28543        29132          576         >19.72\nuvw1              4788         4988          196          18.47+-0.19\nuvw1             23318        46354         1633          20.20+-0.27\nuvm2              4583         6169          344          18.58+-0.18\nuvm2             44762        45661          885         >20.37\nuvw2              4174         5809          393          19.53+-0.26\nuvw2             32392        40613         1700         >20.86\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.04 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 21207,
  "createdOn": 1496689810000,
  "email": "siegel@swift.psu.edu",
  "subject": "GRB 170604A: Swift/UVOT Observations",
  "submitter": "Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>",
  "eventId": "GRB 170604A"
}