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GCN Circular 9625

GRB 090709: Swift detection of a bright burst
2009-07-09T08:07:08Z (15 years ago)
David Palmer at LANL <>
D. C. Morris (PSU), A. P. Beardmore (U Leicester),
P. A. Evans (U Leicester), H. A. Krimm (CRESST/GSFC/USRA),
V. Mangano (INAF-IASFPA), J. Mao (INAF-OAB),
C. B. Markwardt (CRESST/GSFC/UMD), K. L. Page (U Leicester),
D. M. Palmer (LANL), A. Rowlinson (U Leicester), M. H. Siegel (PSU),
M. A. Stark (PSU), G. Tagliaferri (INAF-OAB),
T. N. Ukwatta (GSFC/GWU) and H. Ziaeepour (UCL-MSSL) report on behalf
of the Swift Team:

At 07:38:34 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 090709 (trigger=356890).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 289.933, +60.731 which is 
   RA(J2000) = 19h 19m 44s
   Dec(J2000) = +60d 43' 52"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed about four major
peaks starting at T-20 and continuing to T+100 seconds. The peak 
count rate was ~15000 counts/sec (15-350 keV), at ~25 sec after the trigger. 

The XRT began observing the field at 07:39:42 UT, 67.8 seconds after the BAT
trigger. In the 2.5-s image-mode data we find a fading, uncatalogued X-ray
source with a position: RA, Dec 289.9291, +60.7271 which is equivalent to:
   RA(J2000)  = 19h 19m 42.99s
   Dec(J2000) = +60d 43' 37.5"
with an uncertainty of 4 arcseconds (radius, 90% containment). This
location is 16 arcseconds from the BAT onboard position, within the BAT
error circle. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 76 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The overlap of the sub-image and the
XRT error circle is 100%. The overlap of the 8'x8' region for the list of
sources generated on-board and the XRT error circle is 100%. No correction
has been made for the expected extinction corresponding to E(B-V) of 0.09. 

Burst Advocate for this burst is D. C. Morris (morris AT 
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:
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