GCN Circular 9454

M. Stamatikos (NASA/ORAU), S. D. Barthelmy (GSFC), C. Gronwall (PSU),
S. T. Holland (CRESST/USRA/GSFC), V. Mangano (INAF-IASFPA) and
D. M. Palmer (LANL) report on behalf of the Swift Team:

At 01:45:17 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 090531 (trigger=353627).  Swift could not immediately slew
to the burst location.  The BAT on-board calculated location is 
RA, Dec 178.687, +7.799 which is 
   RA(J2000) = 11h 54m 45s
   Dec(J2000) = +07d 47' 58"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 50 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~10 sec after the trigger. 

Because of a Moon constraint, Swift could not slew, and there
will be no XRT or UVOT observations until June 3. 

Burst Advocate for this burst is M. Stamatikos (michael 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.)