TITLE: GCN CIRCULAR NUMBER: 17998 SUBJECT: Trigger 648422: Swift possible detection of a source in NGC4552 DATE: 15/07/09 22:02:08 GMT FROM: Scott Barthelmy at NASA/GSFC A. Melandri (INAF-OAB), S. D. Barthelmy (GSFC), M. G. Bernardini (INAF-OAB), P. D'Avanzo (INAF-OAB), A. Y. Lien (GSFC/UMBC), B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 21:42:17 UT, the Swift Burst Alert Telescope (BAT) triggered and located a possible source near NGC4552 (trigger=648422). Swift did not slew because of an earth-limb observing constraint. The BAT on-board calculated location is RA, Dec 188.824, +12.672, which is RA(J2000) = 12h 35m 18s Dec(J2000) = +12d 40' 20" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). We note that this is ~9 arcmin NGC 4552, and as such it allows for a lower threshold value not the trigger criteria. As is typical for image triggers, there is nothing significant in the real-time light curve. When the source location comes out of observing constraint (at T+49 minutes), Swift will slew to it and then XRT and UVOT will produce their usual automated data products. And then a refined circular will be issued about the identity and reality of this trigger. Burst Advocate for this burst is A. Melandri (andrea.melandri AT brera.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.)