[vsnet-grb-info 6504] GRB 080822: Swift detection of a short burst

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8112
SUBJECT: GRB 080822: Swift detection of a short burst
DATE:    08/08/22 13:08:50 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

S. T. Holland (CRESST/USRA/GSFC), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),
D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC),
O. Godet (U Leicester), C. Guidorzi (INAF-OAB), J. A. Kennea (PSU),
V. Mangano (INAF-IASFPA), J. Mao (INAF-OAB),
F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester),
J. P. Osborne (U Leicester), C. Pagani (PSU),
K. L. Page (U Leicester), D. M. Palmer (LANL), M. Perri (ASDC),
T. Sakamoto (NASA/UMBC), B. Sbarufatti (INAF-IASFPA),
R. L. C. Starling (U Leicester), G. Stratta (ASDC) and
T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:

At 12:41:59 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 080822 (trigger=321174).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 75.270, +45.272 which is 
   RA(J2000)  =  05h 01m 05s
   Dec(J2000) = +45d 16' 20"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single spike
with a duration of less than 128 msec.  The peak count rate
was ~10000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 12:43:16.3 UT, 77.1 seconds after
the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued
X-ray source with an enhanced position: RA, Dec 75.27800, 45.27623
which is equivalent to:
   RA(J2000)  = 05h 01m 6.72s
   Dec(J2000) = +45d 16' 34.4"
with an uncertainty of 2.6 arcseconds (radius, 90% containment). This
location is 25 arcseconds from the BAT onboard position, within the BAT
error circle. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (5.22e+21
cm^-2, Kalberla et al. 2005), with an excess column of 3.6
(+3.64/-2.95) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 100 seconds with the White  
(160-650 nm)  filter starting 83 seconds after the BAT trigger. No  
afterglow candidate is apparent in the initial data products.  The  
TDRSS source list covers 100% of   the XRT error circle. The list
of sources is typically complete to about 18 mag.  No  correction
has been made for the expected extinction corresponding to E(B-V)
= 1.29 mag. 

We note that the XRT position is 10.8 arcsec from the catalog position
of the ROSAT source 2RXP J050107.7+451637. 

Burst Advocate for this burst is S. T. Holland (sholland 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.)