{
  "bibcode": "2019GCN.24587....1K",
  "body": "N. P. M. Kuin (UCL-MSSL) and M. G. Bernardini (INAF-OAB)\nreport on behalf of the Swift/UVOT team:\n\nIn GCN Circ. 24494 (Kuin and Bernardini) we described how we detect\nthe afterglow of the GRB, but that the photometry was affected by\nan object located at a distance of 1.3 arcsec. Further Swift\nobservations show that the uv-optical afterglow was no longer\ndetected in white beyond 26ks after the trigger. Data that were taken\nafter that time are considered template observations that\nprovide the background contribution to the photometry.\n\nThe template net corrected count rates, with instrumental effects\nremoved, are found to be as follows for a 3\" radius circular aperture\nat the location of the GRB as reported in GCN 24494:\nWhite = 1.066 +/- 0.031 c/s; u = 0.149 +/- 0.016 c/s;\nb = 0.509 +/- 0.061 c/s; uvw2 =  0.011 +/- 0.011 c/s;\nv = 0.272 +/- 0.042 c/s; while uvm2 and uvw1 were not observed\nuntil after the afterglow became too faint.\n\nAfter removal of the template contribution, the following preliminary\ndetections and 3-sigma upper limits were determined from the count rates\nusing the zeropoints in the UVOT photometric system (Poole et al. 2008,\nMNRAS 383, 627; Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for\nthe image mode exposures:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)           Mag\n\nwhite              131          281          147          15.96 +/- 0.05\nu                  290          385           93          19.62 +/- 0.42\nb                 5684         5884          197          > 20.13\nwhite             5888         6088          197          20.61 +/- 0.37\nuvw2              6094        11850          518          > 17.81\nv                17150        17450          300          > 19.35\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.09 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 24587,
  "createdOn": 1558124107000,
  "email": "npkuin@gmail.com",
  "subject": "GRB 190511A: Swift/UVOT further analysis",
  "submitter": "Paul Kuin at MSSL  <npkuin@gmail.com>",
  "eventId": "GRB 190511A"
}