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GCN Circular 9277

Subject
IPN triangulation of very bright GRB 090427
Date
2009-04-28T11:00:20Z (15 years ago)
From
Valentin Pal'shin at Ioffe Inst <val@mail.ioffe.ru>
V. Pal'shin, S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets,
P. Oleynik, D. Svinkin, M. Ulanov on behalf of the Konus-Wind and 
Konus-RF teams,

K. Hurley and T. Cline, on behalf of the Mars Odyssey
and Konus GRB teams,

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

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

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

E. Del Monte, E. Costa, I. Donnarumma, Y. Evangelista, M. Feroci,
I. Lapshov, F. Lazzarotto, L. Pacciani, M. Rapisarda, P. Soffitta,
on behalf the SuperAGILE team,

A. von Kienlin, G. Lichti, and A. Rau, and K. Hurley on behalf of the
INTEGRAL SPI-ACS team report:

Konus-Wind, Konus-RF, Mars-Odyssey (GRS and HEND), SuperAGILE, 
AGILE-MCAL, and INTEGRAL-SPI-ACS observed the bright GRB 090427 at about 
84387 s UT (23:26:27). The burst was outside the coded field of view of 
the SuperAGILE.

The burst light curve shows a multipeaked structure with a duration of
~15 sec.

We have triangulated it to the following 3-sigma error box:
-----------------------------------------------
    RA(2000), deg              Dec(2000), deg
-----------------------------------------------
Center:
  235.931 (15h 43m 43s)   -13.498 (-13d 29' 53")
Corners:
  236.026 (15h 44m 06s)   -12.481 (-12d 28' 52")
  236.183 (15h 44m 44s)   -12.470 (-12d 28' 12")
  235.820 (15h 43m 17s)   -14.521 (-14d 31' 16")
  235.658 (15h 42m 38s)   -14.542 (-14d 32' 30")
-----------------------------------------------

The error box area is 0.313 sq. deg.
This error box may be improved.

Preliminary analysis of the Konus-Wind data yields
a burst fluence of ~1x10^-4 erg/cm2 (in the 20 keV - 8 MeV range),
and an Epeak of the time-integrated spectrum of ~750 keV.

IPN triangulation map is available at 
http://www.ioffe.ru/LEA/GRBs/GRB090427_T84392/IPN/
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