Burst H2380 summary Trigger time is UTC=20021004_120613 GRB=GRB021004+43573 Triggering instrument was Fregate Trigger timescale was 5.2 seconds Trigger detected in 30-400 keV band Evaluation Definite GRB. Bright OT detected 9.5 minutes after burst.

The localization history of H2380 (GRB021004)

HETE GCNs for GRB021004

GCN 1564: GRB021004(=H2380): A Long GRB Localized by HETE in Real Time

Y. Shirasaki, C. Graziani, M. Matsuoka, T. Tamagawa, K. Torii,
T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, and
T. Donaghy, 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;

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

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

write:


At 12:06:13.57 UTC (43573.57 s UT) on 4 Oct 2002, the HETE FREGATE,
WXM, and SXC instruments detected event H2380, a long GRB.  The WXM
flight localization was correct and was reported in a GCN Position
Notice at 12:07:02 UT, 49 sec after the beginning of the burst.

Ground analysis of the WXM data for the burst produced a refined
location, which was reported in a GCN Position Notice at 13:19:54 UT,
73 minutes after the burst.  The WXM localization SNR was 14.  The WXM
location can be expressed as a 90% confidence circle that is 10
arcminutes in radius and is centered at

RA = 00h 26m 47s, Dec = +18d 59' 13" (J2000).

Ground analysis of the SXC data for the burst produced a further
refinement in the location, which was reported in a GCN Position Notice
at 14:39:51 UT, 154 minutes after the burst.  The SXC localization SNR
was 9.  The SXC location can be expressed as a 90% confidence circle
that is 2 arcminutes in radius and is centered at

RA = 00h 26m 57s, Dec = +18d 55' 44" (J2000).

The SXC localization may be improved.

In the FREGATE 8-40 keV band, the burst had a duration of ~100 seconds.
In the WXM 2-25 keV band, the burst also had a duration of ~100
seconds.

A light curve for GRB021004 is provided at the following URL:

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

This message is citable.

GCN 1568: GRB021004(=H2380): Revised Localization with HETE Soft X-ray Cameras

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

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

C. Graziani, Y. Shirasaki, M. Matsuoka, T. Tamagawa, K. Torii, T.
Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, and T.
Donaghy, on behalf of the HETE WXM Team;

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

write:

Analysis of the full data set derived from the HETE Soft X-ray Camera
(SXC) has resulted in a revised location for GRB021004(=H2380;
Shirasaki et al, GCN Circular #1565). The revised SXC location can be
expressed as a 90% confidence circle that is 62 arcsec in radius and
is centered at:

RA = 00h 26m 55.7s, Dec = +18d 56' 18.6" (J2000)

This revised SXC localization is shifted 38 arcsec with respect to,
but lies fully within, the original 120 arcsec radius SXC error
circle reported by Shirasaki et al in GCN1565. The fading optical
transient reported by Fox in GCN1564 is 40 arcsec from the center of,
and is within, this revised SXC error circle.

Further information regarding GRB021004 is provided at the following URL:

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

This message is citable.

GCN 1600: HETE fluences for GRB021004

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

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

Y. Shirasaki, M. Matsuoka, T. Tamagawa, K. Torii, T. Sakamoto,
A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, C. Graziani, and
T. Donaghy, on behalf of the HETE WXM Team;

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

write:

Analysis of the FREGATE data for GRB021004 (=H2380) shows that
the fluence-averaged photon number spectrum of the burst is well-fit
by a single power-law spectrum with slope alpha = 1.64 +/- 0.09, and
gives the following values for the fluences of the burst:

S = 1.8 x 10-6 erg cm-2 (50-300 keV), and

S = 3.2 x 10-6 erg cm-2 (7-400 keV).

Using the latter value and assuming Omega_Lambda = 0.7, Omega_m = 0.3,
and H_0 = 70 km s-1 Mpc-1, the isotropic-equivalent energy of the
burst is

E_iso = 2.06 x 10^(52) ergs.

Using this value of E_iso and equation (1) of Frail et al. (ApJ 562,
L55, 2001) [see also Sari et al. (ApJ 519, L17, 1999)] to estimate the
jet break time, we find

t_j = 1.3 [(1+z)/2.60] (theta_j/0.070)^(8/3) [E_iso/2 x 10^(52) ergs]
           x (eta/0.2)^(-1/8) (n/0.1 cm-3)^(-1/8)  days.


Analysis of the WXM data for GRB021004 gives the following value for the
fluence of the burst in the WXM energy band:

S = 7.5 x 10-7 erg cm-2 (2-25 keV).

The fluence ratio S(2-25)/S(50-300)= (7.5 x 10-7)/(1.8 x 10-6) = 0.42
implies that GRB021004 is an X-ray rich GRB [log (S_x/S_gamma) > -0.5].

This message is citable.