TITLE: GCN CIRCULAR NUMBER: 17963 SUBJECT: Trigger 646721: Swift detection of V 404 Cyg DATE: 15/06/26 13:03:00 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team: At 12:49:38 UT, the Swift Burst Alert Telescope (BAT) triggered and located V404 Cyg (trigger=646721). Swift was already observing this location because of a TOO commanded upload. The BAT on-board calculated location is RA, Dec 306.006, +33.868 which is RA(J2000) = 20h 24m 02s Dec(J2000) = +33d 52' 06" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). We are not reporting a light curve due to a loss of a data packet in the TDRSS real-time.