TITLE: GCN CIRCULAR NUMBER: 16415 SUBJECT: GRB 140619A: Swift detection of a burst with a possible optical counterpart DATE: 14/06/19 11:56:35 GMT FROM: David Burrows at PSU/Swift M. De Pasquale (INAF-IASFPA), D. N. Burrows (PSU), S. B. Cenko (GSFC), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (NASA/GSFC/ORAU), F. E. Marshall (NASA/GSFC), A. Maselli (INAF-IASFPA), K. L. Page (U Leicester), B. Sbarufatti (INAF-OAB/PSU) and T. N. Ukwatta (MSU) report on behalf of the Swift Team: At 11:38:35 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 140619A (trigger=602080). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 27.092, -39.261 which is RA(J2000) = 01h 48m 22s Dec(J2000) = -39d 15' 40" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual with an image trigger, the available BAT light curve shows no significant structure. The XRT began observing the field at 11:40:54.9 UT, 139.1 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 27.1084, -39.2586 which is equivalent to: RA(J2000) = +01h 48m 26.02s Dec(J2000) = -39d 15' 31.0" with an uncertainty of 4.8 arcseconds (radius, 90% containment). This location is 46 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 2.5 s image was 5.85e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 98 seconds with the White filter starting 147 seconds after the BAT trigger. There is a weak 20.5 mag source near the XRT position. No aspect UVOT aspect solution is available because of the paucity of stars. Confirmation of the afterglow will require the full data set. No correction has been made for the expected extinction corresponding to E(B-V) of 0.01. Burst Advocate for this burst is M. De Pasquale (mdp AT ifc.inaf.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)