GCN Circular 18249

T. G. R. Roegiers (PSU), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC),
D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and
T. N. Ukwatta (LANL) report on behalf of the Swift Team:

At 23:26:27 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150907B (trigger=654803).  Swift could not slew
immediately to the burst due to an observing constraint. 
The BAT on-board calculated location is 
RA, Dec 255.219, -63.819 which is 
   RA(J2000) = 17h 00m 53s
   Dec(J2000) = -63d 49' 07"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  Only partial BAT lightcurve data is available,
but the light curve shows a complex structure at least 10 seconds long. 
The peak count rate was ~1500 counts/sec (15-350 keV), at ~0 sec 
after the trigger. 

Due to an observing constraint, Swift will not slew until T0+49.0
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is T. G. R. Roegiers (troegiers AT swift.psu.edu). 
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.)