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GCN Circular 9835

Subject
GRB 090823 Long burst with IPN triangulation and BAT position
Date
2009-08-25T01:36:20Z (14 years ago)
From
Jay R. Cummings at NASA/GSFC/Swift <jayc@milkyway.gsfc.nasa.gov>
J. R. Cummings (NASA/GSFC/CRESST) on behalf of the
Swift-BAT team,

S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin,
D. Frederiks, and T. Cline on behalf of the Konus-Wind team,

M. Marisaldi, F. Fuschino, C. Labanti, M. Galli,
G. Di Cocco on behalf of the AGILE team,

K. Yamaoka, M. Ohno, Y. Fukazawa, T. Takahashi, M. Tashiro,
Y. Terada, T. Murakami, K. Makishima, and Y. Hanabata on
behalf of the Suzaku-WAM team,

and K. Hurley for the IPN

At 16:11:12 on 2009-08-23, GRB 090823 triggered the
Suzaku WAM.  The IPN was notified, and the burst was
also observed by KONUS-Wind, Agile-MCAL, and (during a
slew maneuver) Swift-BAT. A source was found in ground
analysis of BAT event data, which is routinely collected
during many pre-planned slews, and the source location
was confirmed by IPN triangulation.

The BAT position is RA, Dec 228.711, 60.660 which is
equivalent to

      RA, Dec (J2000): 15:14:50.6,  60d 39' 36"

with an uncertainty radius of 4 arcmin (estimated 90%
containment, stat+sys).

We have triangulated GRB 090823 to a Konus-WAM annulus
centered at RA(2000)=141.472 (09h 25m 53s)
Dec(2000)=+9.275 (+9d 16' 31"), whose radius is
52.640 � 4.346 deg (3 sigma). The BAT source is
0.384 deg (0.27 sigma) from the center line of the
annulus.

As observed in Suzaku-WAM and Agile-MCAL, the burst had
two peaks at about T+1 and T+4 seconds, and had emission
above 700 keV but not above 1.4 MeV. The BAT lightcurve
shows that the emission began with a slow rise beginning
about T-3 seconds, and decayed back to background rates
by about T+20 seconds. The BAT event data, from which
mask-weighted spectra and images are constructed, began
at about T+10.5 seconds, missing 99% of the burst.

A Swift Target of Opportunity has been requested and
approved to follow up this burst with the Swift XRT and
UVOT about 32 hours after the burst.
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