{
  "subject": "GRB 200509A: Swift/UVOT Detection",
  "eventId": "GRB 200509A",
  "bibcode": "2020GCN.27709....1K",
  "createdOn": 1589070880000,
  "circularId": 27709,
  "submitter": "Paul Kuin at MSSL  <npkuin@gmail.com>",
  "email": "npkuin@gmail.com",
  "body": "N. P. M. Kuin (UCL-MSSL) and E. Troja (NASA/GSFC/UMCP)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 200509A\n123 s after the BAT trigger (Troja et al., GCN Circ. 27701). A source\nconsistent with the XRT position  (Troja et al. GCN Circ. 27701)  is\ndetected in the initial UVOT exposures.\n\nThe preliminary UVOT position is:\n    RA  (J2000) =  07:45:41.28 = 116.42200 (deg.)\n    Dec (J2000) = -04:37:49.3  =  -4.63035 (deg.)\nwith an estimated uncertainty of 0.48 arc sec. (radius, 90% confidence).\n\nPreliminary detections and 3-sigma upper limits using the UVOT\nphotometric 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              123          273          147         18.92 +/- 0.08\nv                  611         1738          122        >18.6\nb                  537         1678          117        >19.8\nu                  281          531          246         18.46 +/- 0.10\nw1                 660         1628          117        >19.0\nm2                 636         1604          117        >19.0\nw2                 587         1728          136        >19.6\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.13 in the direction of the burst\n(Schlegel et al. 1998)."
}