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GCN Circular 2358

Subject
GRB 030821(=H2814): A Faint, Long GRB Localized by the HETE WXM and the IPN
Date
2003-08-22T02:02:16Z (21 years ago)
From
Don Lamb at U.Chicago <lamb@oddjob.uchicago.edu>
T. Donaghy, C. Graziani, Y. Shirasaki, T. Tamagawa, M. Suzuki, M.
Matsuoka, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi,
Y. Nakagawa, R. Satoh, Y. Urata, T. Yamazaki and Y. Yamamoto, on
behalf of the HETE WXM Team;

G. Ricker, J-L. Atteia, N. Kawai, D. Lamb, and S. Woosley on behalf
of the HETE Science Team;

G. Prigozhin, N. Butler, G. Crew, J. Doty, A. Dullighan, R. Vanderspek,
J. Villasenor, J. G. Jernigan, A. Levine, F. Martel, E. Morgan, G.
Monnelly, G. Azzibrouck, J. Braga, R. Manchanda, and G. Pizzichini, on
behalf of the HETE Operations and HETE Optical-SXC Teams;

C. Barraud, M. Boer, J-F Olive, and J-P Dezalay on behalf  of the HETE
FREGATE Team;

K. Hurley and T. Cline, on behalf of the Ulysses, HETE, Mars Odyssey,
and KONUS GRB teams;

I. Mitrofanov, S. Charyshnikov, V. Grinkov, A. Kozyrev, M. Litvak, and
A. Sanin, on behalf of the HEND-Odyssey GRB team;

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

E. Mazets and S. Golenetskii, on behalf of the Konus-Wind GRB team;

A. von Kienlin, G. Lichti, and A. Rau, on behalf of the INTEGRAL
SPI-ACS GRB team,

report:

At 05:31:50 UTC (19895.60 s UT) on 21 August 2003, the HETE FREGATE
and WXM instruments detected GRB 030821 (=H2814), a faint long GRB.

The burst triggered FREGATE in the 25-400 keV energy band.  A GCN burst
alert was issued 15 s later.  The burst was faint and located at
the edge of the FOV of the WXM YB counter; hence no WXM flight
localization was derived.  Ground analysis of the WXM data provided a
localization that was reported in a GCN Notice (Seq. 3) at 08:45:53 UT.

Mars Odyssey (HEND), Konus-Wind, and INTEGRAL (SPI-ACS) also observed
this burst.  Triangulation of the burst produces a preliminary annulus
centered at

RA = 341.285, Dec = -15.283 (J2000),

whose radius is 32.642 +/- 1.153 degrees (3 sigma).  This annulus does
not include the initial (Seq. 3) HETE-2 WXM ground analysis location,
but is fully consistent with the revised ground analysis location that
was reported in a GCN Notice (Seq. 4) at 22:12:10 UT.  The revised WXM
ground analysis localization can be expressed as a rectangle that is 33
arcminutes wide and 3.3 degrees long, whose center is at

WXM Center-ground:   RA = +21h 42m 33s, Dec = -45d 12' 12" (J2000).

The four corners of the WXM localization region are located at the
following coordinates (J2000):

WXM_CORNER1:    RA = +21h 41m 48s, Dec = -43d 35'  2"
WXM_CORNER2:    RA = +21h 45m 58s, Dec = -46d 46' 16"
WXM_CORNER3:    RA = +21h 43m 16s, Dec = -46d 49' 23"
WXM_CORNER4:    RA = +21h 39m 10s, Dec = -43d 38' 10"

The burst was very faint in the SXC X-camera and was outside the FOV of
the SXC Y-camera; hence an SXC localization is unlikely.

The T_90 duration of the burst in the 30-400 keV band was ~ 19 s.  The
peak photon energy flux in 1 s and the fluence of the burst were 4.8 x
10-7 ergs cm-2 s-1 and 5.7 x 10-6 ergs cm-2, respectively, in the same
energy band.

Ulysses data are expected shortly, and may constrain the localization
further.

A light curve and finding chart for GRB030821 are provided at the
following URL:

http://space.mit.edu/HETE/Bursts/GRB030821
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