TITLE:   GCN CIRCULAR
NUMBER:  29677
SUBJECT: GRB 210321A: Swift detection of a burst
DATE:    21/03/21 07:22:33 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

S. Dichiara (NASA/GSFC/UMCP), C. Gronwall (PSU), H. A. Krimm (NSF),
K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 07:13:51 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210321A (trigger=1037828).  Swift did not immediately slew
due to an observing constraint. 
The BAT on-board calculated location is 
RA, Dec 87.874, +70.119 which is 
   RA(J2000) = 05h 51m 30s
   Dec(J2000) = +70d 07' 09"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 15 sec.  The peak count rate
was ~1300 counts/sec (15-350 keV), at ~1 sec after the trigger. 

Due to an observing constraint, Swift will not slew until T0+43.3
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is S. Dichiara (dichiara AT umd.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/)