GCN Circular 9461

J. R. Cummings (NASA/UMBC), S. D. Barthelmy (GSFC),
N. Gehrels (NASA/GSFC), C. Gronwall (PSU),
S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU),
V. Mangano (INAF-IASFPA), C. B. Markwardt (CRESST/GSFC/UMD),
P. T. O'Brien (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), T. Sakamoto (NASA/UMBC) and
B. Sbarufatti (INAF-IASFPA) report on behalf of the Swift Team:

At 18:35:56 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 090531B (trigger=353728).  Swift will execute a delayed slew
to the burst. 
The BAT on-board calculated location is 
RA, Dec 252.064, -36.025 which is 
   RA(J2000)  =  16h 48m 15s
   Dec(J2000) = -36d 01' 27"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows an initial bright spike
at T_zero, then two much smaller spikes at T+21 sec and T+35 sec. 
The peak count rate was ~7000 counts/sec (15-350 keV), at ~0 sec
after the trigger. 

Due to an observing constraint, Swift will not slew until 
T0+50.1 minutes. There will be no XRT or UVOT data until
this time. 

Burst Advocate for this burst is J. R. Cummings (jayc AT milkyway.gsfc.nasa.gov). 
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.)