GCN Circular 2358

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