{
  "bibcode": "2020GCN.28742....1S",
  "body": "M. H. Siegel (PSU) and E. Ambrosi (INAF-IASFPA)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 201020A\n144 s after the BAT trigger (Ambrosi et al., GCN Circ. 28696).\nWe confirm the fading source initially reported by Ambrosi et al. and\nsince confirmed by numerous observations (Adachi et al., GCN \nCirc. 28697; Fu  et al., GCN Circ. 28701;  Belkin et al., GCN Circ. 28703,\nPankow et al. GCN Circ. 28708, Kumar et al. GCN Circ. 28711, Paek et al.\nGCN Circ. 28713).  The afterglow is not detected in UVOT's NUV filters,\nwhich would be consistent with the redshift of 2.9 reported by Kann et al.\n(GCN Circ. 28717).\n\nThe preliminary UVOT position is:\n   RA  (J2000) =  17:24:54.66 = 261.22773 (deg.)\n   Dec (J2000) = +31:25:42.1  =  31.42837 (deg.)\nwith an estimated uncertainty of 0.44 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)         145          294          147      18.19+/-0.05\nwhite              583          775           38      19.39+/-0.23\nwhite             9805        10713          885      19.71+/-0.09\nwhite           131168       131712          531            >21.48\nv                  632          826           38      17.91+/-0.28\nv                21653        22150          485      19.26+/-0.28\nv                34473        35292          798      19.86+/-0.29\nv               125782       126429          629            >19.99\nb                  558          750           38            >19.30\nb                22822        23469          630      20.35+/-0.21\nb                39219        39998          759      21.05+/-0.36\nb               130256       131163          885            >20.60\nu (fc)             303          552          245      19.76+/-0.27\nu                  706          726           19            >18.42\nu                29427        29557          128            >19.69\nuvw1               681          876           38            >18.16\nuvw1             28521        29420          885            >20.42\nuvm2               656          676           19            >17.06\nuvm2             27614        28514          885            >20.29\nuvw2               608          800           38            >18.04\nuvw2             10719        34466         1329            >20.71\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": 28742,
  "createdOn": 1603368981000,
  "email": "mhs18@psu.edu",
  "subject": "GRB 201020A: Swift/UVOT Observations",
  "submitter": "Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>",
  "eventId": "GRB 201020A"
}