[vsnet-grb-info 13817] GRB 130829A: Swift detection of a burst

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15131
SUBJECT: GRB 130829A: Swift detection of a burst
DATE:    13/08/29 18:20:10 GMT
FROM:    David Palmer at LANL  <palmer at lanl.gov>

D. Grupe (PSU), D. N. Burrows (PSU), S. T. Holland (STScI),
J. A. Kennea (PSU), A. Y. Lien (NASA/GSFC/ORAU),
C. J. Mountford (U Leicester), P. T. O'Brien (U Leicester) and
M. H. Siegel (PSU) report on behalf of the Swift Team:

At 05:43:33 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130829A (trigger=568417).  Swift could not slew to the
burst location due to a Sun constraint.  Due to this source's apparent 
proximity to the Galaxy NGC 4144, this was originally reported as a 
transient and no GCN circular was issued. 

Using the data set from T-239 to T+303 sec from the recent telemetry downlink,
we report the detection of BAT GRB 130829A (trigger #568417).  
The BAT ground-calculated position is
RA, Dec = 182.426, 46.520 deg which is
   RA(J2000)  =  12h 09m 42.1s
   Dec(J2000) = +46d 31' 10.8"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). 
The partial coding was 84%. 

The mask-weighted light curve shows a long peak starting from ~T+34 and 
ending at ~T+77. T90 (15-350 keV) is 42.56 +- 7.08 sec (estimated error 
including systematics). 

The time-averaged spectrum from T+30.86 to T+87.50 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.36 +- 0.12.  The fluence in the 15-150 keV band is 1.2 +- 0.1 x 10^-06 erg/cm2. 
The 1-sec peak photon flux measured from T+50.90 sec in the 15-150 keV band
is 0.6 +- 0.1 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/568417/BA/

The nominal (Simbad) coordinates of galaxy NGC 4144 are
2.8 arcmin East and 3.8 arcmin North of the BAT GRB location. 
This places the entire BAT error circle outside of the bright
visible area of the galaxy, but the position would be consistent
with an extended spherical halo. 

Due to an observing constraint, Swift XRT or UVOT cannot observe
this region until September 24th, 2013. 

Burst Advocate for this burst is D. Grupe (dxg35 AT 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.)