{
  "bibcode": "2019GCN.25964....1T",
  "body": "A . Tohuvavohu (U. Toronto), N. P. M. Kuin (UCL-MSSL), S. R. Oates\n(Uni. of Warwick),  A. A. Breeveld (MSSL-UCL),\nF. E. Marshall (NASA/GSFC), P. Brown (TAMU),C. Gronwall (PSU),\nM. J. Page (UCL-MSSL), M. De Pasquale (Istanbul U.),\nM. H. Siegel (PSU), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB),\nS. D. Barthelmy (NASA/GSFC), A. P. Beardmore (U. Leicester), D. N.\nBurrows (PSU),\nS. Campana (INAF-OAB), S. B. Cenko (NASA/GSFC), G. Cusumano (INAF-IASF PA),\nV. D'Elia(ASDC), P. A. Evans (U. Leicester), P. Giommi (ASI),\nD. Hartmann (Clemson U.), J. A. Kennea (PSU), N. J. Klingler (PSU),\nH. A. Krimm (NSF), A. Y. Lien (GSFC/UMBC), D. B. Malesani (DTU Space),\nA. Melandri (INAF-OAB),  J. A. Nousek (PSU), P. T. O'Brien (U. Leicester),\nJ. P. Osborne (U. Leicester), C. Pagani (U. Leicester), K. L. Page\n(U.Leicester),\nD.M. Palmer (LANL),  M. Perri (ASDC), J. L. Racusin (NASA/GSFC),\nT. Sakamoto (AGU),  B. Sbarufatti (INAF-OAB/PSU), G. Tagliaferri (INAF-OAB),\nand E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team:\n\nWe report the discovery of Swift J224718-581442 a  transient found\nin the UVOT and XRT search results of the LVC event\nS190930t (LIGO/Virgo Collaboration GCN Circ. 25876).\n\nOn 2019-10-01 07:19:41 (GW T0+17 hours) UT Swift UVOT took\n a 75 s exposure in the u band with observation ID 07021863001.\nAn uncatalogued source was found.\nThe new source is not listed in the USNO-B1,  Gaia DR1, GSC2.3 or 2MASS\ncatalogues and is not listed as a minor planet.\n\nThe UVOT position is\n\n    RA (J2000)  22:47:18.100= 341.825417\n   Dec (J2000) -58:14:50.80  = -58.247444\n\nThe magnitude using the UVOT photometric system  (Breeveld et al. 2011, AIP\nConf. Proc. 1358, 373) was u = 18.76 +/- 0.21 mag (Vega).\n\nOn 2019-10-04 05:01:0 UT Swift UVOT took another 78 s exposure in the u band\nwith observation ID 07400055001. The source is found to have faded by\n > 1 mag, to u = 19.84  (Vega).\n\nA faint uncatalogued X-ray source is found by XRT 1.9 arcseconds away,\nconsistent with the location of the UVOT source.\n\nThe  X-ray source is located at RA, Dec 341.82803, -58.2451 which\nis equivalent to:\n   RA(J2000)  = 22h 47m 18.73s\n   Dec(J2000) = -58d 14��� 42.3���\n\nThe count rate of this source is measured in XRT at 0.013 (��0.004) ct s-1.\n\nThis source is located on the outskirts of the galaxy 2MASX J22471856-5814422,\nwith a redshift of z=0.054 (D~240 Mpc), ~ 4 sigma above the mean GW\ndistance along this line of sight (mean = 94 Mpc, sigma = 34 Mpc).\n\nWe encourage spectroscopic followup of this transient.\nFurther Swift UVOT and XRT observations are planned.\n\nThis transient has been reported to the TNS as AT2019sbk.\n\nThis circular is an official product of the Swift team.",
  "circularId": 25964,
  "createdOn": 1570407809000,
  "email": "aaron.kholodenko@gmail.com",
  "subject": "LIGO/Virgo S190930t: Swift discovery of Swift J224718-581442 (AT2019sbk): a fading UV transient with an X-ray counterpart",
  "submitter": "Aaron Tohuvavohu at U Toronto  <aaron.kholodenko@gmail.com>",
  "eventId": "LIGO/Virgo S190930t"
}