{
  "bibcode": "2018GCN.22810....1S",
  "body": "M. H. Siegel (PSU) and S. J. LaPorte (PSU)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 180618A\n86 s after the BAT trigger (LaPorte et al., GCN Circ. 22790). We confirm\nthe previously reported fading optical afterglow, also detected by LT (Guidorzi \net al., GCN Circ. 22792) and MASTER (Tyurina et al., GCN Circ. 22797). We find\nthat the source had faded away completely by the second orbit. The detection of the\nafterglow in six of UVOT's filters places an upper limit on the redshift of z < 1.2.\n\nThe preliminary UVOT position is:\n    RA  (J2000) =  11:19:45.84 = 169.94102 (deg.)\n    Dec (J2000) = +73:50:13.5  =  73.83707 (deg.)\nwith an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).\n\nPreliminary detections and 3-sigma upper limits using the UVOT photometric system\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: \n\nFilter         T_start(s)   T_stop(s)      Exp(s)           Mag\n\nwhite (fc)          86          236          147         17.46 +/- 0.04\nwhite               86         1544          390         17.95 +/- 0.03\nwhite             5680         7315          393        >21.09\nv                  628         1596          117         18.71 +/- 0.22\nv                 6090         6290          196        >19.25\nb                  553         1175           58         18.84 +/- 0.16\nb                 5475         7110          393        >20.39\nu (fc)             298          548          246         17.50 +/- 0.06\nu                  298         1497          313         17.62 +/- 0.06\nu                 5270         6905          393        >19.94\nw1                 676         1472           97         18.59 +/- 0.24\nw1                5065         6700          393        >19.63\nm2                1254         1621           58        >17.6\nw2                 604         1398           97         18.85 +/- 0.28\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.07 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 22810,
  "createdOn": 1529518517000,
  "email": "siegel@swift.psu.edu",
  "subject": "GRB 180618A: Swift/UVOT Detection",
  "submitter": "Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>",
  "eventId": "GRB 180618A"
}