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GRB 091208

GCN Circular 10253

Subject
GRB 091208: Swift detection of a burst
Date
2009-12-08T08:56:56Z (16 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
E. A. Hoversten (PSU), P. A. Evans (U Leicester), C. Gronwall (PSU),
J. Mao (INAF-OAB), C. B. Markwardt (CRESST/GSFC/UMD),
P. T. O'Brien (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), M. Stamatikos (OSU/NASA/GSFC) and L. Vetere (PSU)
report on behalf of the Swift Team:

At 08:46:00 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 091208 (trigger=378554).  Swift could not slew to the burst
due to an Earth limb constraint.  The BAT on-board calculated location is 
RA, Dec 0.274, +65.674 which is 
   RA(J2000) = 00h 01m 06s
   Dec(J2000) = +65d 40' 25"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a FRED
structure with a duration of about 30 sec.  The peak count rate
was ~6000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Due to an observing constraint, Swift will not slew until 
T0+49.7 minutes. There will be no XRT or UVOT data until
this time. 

Burst Advocate for this burst is E. A. Hoversten (hoversten AT astro.psu.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/too.html.)

GCN Circular 10254

Subject
GRB 091208: ROTSE-III Optical Limits
Date
2009-12-08T09:16:45Z (16 years ago)
From
Fang Yuan at ROTSE <yuanfang@umich.edu>
F. Yuan (U Mich), W. Rujopakarn (Steward), W. Zheng (U Mich), report  
on behalf of the ROTSE collaboration:

ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB  
091208 (Swift trigger 378554; E. A. Hoversten et al, GCN 10253),  
producing images beginning 9.6 s after the GCN notice time. An  
automated response took the first image at 08:46:30.5 UT, 30.0 s after  
the burst. We took 10 5-sec and 42 20-sec exposures. These unfiltered  
images are calibrated relative to USNO A2.0 (R). Imaging is on going.

Comparison to the DSS (second epoch) reveals no new sources within the  
3-sigma Swift/BAT error circle, for both single images and coadding  
into sets of 10. Individual images have limiting magnitudes ranging  
from 14.6-16.6; we set the following specific limits.

start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
08:52:40.1   08:57:21.5       281     17.3          399.6       Y
08:57:30.2   09:02:12.0       281     17.4          689.7       Y

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