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GCN Circular 9009

IPN Triangulation of GRB090315 and Tupi Detection of Muon Increase
2009-03-18T23:52:04Z (15 years ago)
Kevin Hurley at UCBerkeley/SSL <>
K. Hurley and T. Cline, on behalf of the Mars Odyssey
and Konus GRB teams,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on
behalf of the GRS-Odyssey GRB team,

S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, and D. Frederiks, 
on behalf of the Konus-Wind team,

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

S. Barthelmy, J. Cummings, N. Gehrels, and H. Krimm, on behalf of
the Swift-BAT team,

J. Goldsten, on behalf of the MESSENGER NS GRB team, 

E. Costa, E. Del Monte, G. Di Cocco, I. Donnarumma, Y. Evangelista, M.
Feroci, F. Fuschino, M. Galli, C. Labanti, I. Lapshov, F. Lazzarotto,
M. Marisaldi, L. Pacciani, M. Rapisarda, and P. Soffitta,  on behalf of the
AGILE MCAL and SuperAGILE teams, and

C. Navia, on behalf of the Tupi collaboration, report:

GRB090315 was observed by Odyssey (HEND and GRS), MESSENGER (GRNS),
Konus-Wind, AGILE (MCAL and SuperAGILE, although the spacecraft was in
the SAA and the background was high; the event was outside the field of
view of SuperAGILE), Suzaku (WAM), and Swift (BAT, but outside the
coded field of view) at 04:12:56 UT.  The burst had a fluence of
several times 10^-5 erg cm^-2  and  a duration of about 9 s (detailed
spectral information will be provided in a separate GCN Circular).  We
have triangulated it to the following preliminary, 3 sigma error box,
whose area is 0.8 sq. deg.

       RA(2000), deg            Dec(2000), deg
  142.641 (09h 30m 34s)   -27.556 (-27d 33' 21")
  140.759 (09h 23m 02s)   -26.958 (-26d 57' 28")
  140.936 (09h 23m 45s)   -27.257 (-27d 15' 25")
  144.531 (09h 38m 07s)   -28.062 (-28d 03' 43")
  144.339 (09h 37m 21s)   -27.782 (-27d 46' 57")

This error box may be improved.

The Tupi ground-based muon telescope (Augusto et al., Phys. Rev. D 77,
123008, 2008) which was pointed in the direction of the burst
registered a significant increase in the count rate in a single 10 s
long bin which included the time of the burst, while a second telescope
whose field of view did not include the burst did not.  (The count
rates and fields of view have been posted at  The muon energy threshold is ~0.1 GeV,
corresponding to primary photons above 10 GeV.  Thus we believe that
the energy spectrum of this GRB extended at least into the multi-GeV
energy range.
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