{
  "bibcode": "2017GCN.21572....1C",
  "body": "S. B. Cenko (NASA/GSFC), S.W.K. Emery (UCL-MSSL), S. Campana (INAF-OAB),��P.A. Evans (U. Leicester), J.A. Kennea (PSU), A.A. Breeveld (UCL-MSSL), E. Troja��(NASA/GSFC/UMCP), P.T. O'Brien (U. Leicester), S.D. Barthelmy��(NASA/GSFC), A.P. Beardmore (U. Leicester), D.N. Burrows (PSU), G. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB),��V.D'Elia(ASDC), P. Giommi (ASI), C. Gronwall��(PSU), H.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), A.Y. Lien��(GSFC/UMBC), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), J.A.��Nousek (PSU), S.R. Oates (U. Warwick), J.P. Osborne (U. Leicester), C.��Pagani (U. Leicester), K.L. Page (U.Leicester), D.M. Palmer (LANL), M.��Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU),��M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), A. Tohuvavohu (PSU) report��on behalf of the Swift team:��\n\nWe obtained a second epoch of UV and X-ray imaging of SSS17a (Coulter et al.; GCN 21529), the candidate optical counterpart of G298048 (LVC; GCN 21509) with the Swift Gamma-Ray Burst Explorer.  Observations began��at 13:30 UT��on 2017��August 18.  Compared with our previous epoch of imaging (Evans et al.; GCN 21550), the source has faded significantly at UV wavelengths.  Specifically we measure the following magnitudes (with no host subtraction):\n\nFilter T_start(s) T_stop(s) Exp(s) Mag (Vega)��\n\nu��   90029 90164  133��17.42 +/- 0.09��\nuvw1��89755 90024  265��18.50 +/- 0.15��\nuvm2��89346 94665 1045��20.40 +/- 0.27��\nuvw2��90170 90674  496��20.37 +/- 0.32��\n\nGiven the relatively flat evolution in the optical and NIR, this suggests significant cooling in the source.\n\nThe source remains undetected in the X-rays, with comparable limits to our previous epoch.\n\nFurther observations are planned.",
  "circularId": 21572,
  "createdOn": 1503081157000,
  "email": "brad.cenko@nasa.gov",
  "subject": "LIGO/Virgo G298048: Continued Swift UV and X-ray Monitoring of SSS17a",
  "submitter": "Brad Cenko at NASA/GSFC  <brad.cenko@nasa.gov>",
  "eventId": "LIGO/Virgo G298048"
}