GRB 010326

G. Ricker, D. Lamb, and S. Woosley on behalf of the HETE Science Team;

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

N. Kawai, M. Matsuoka, Y. Shirasaki, T. Tamagawa, A. Yoshida, E. 
Fenimore, M. Galassi, B. Preger, and  C. Graziani, on behalf of the 
HETE WXM Team;

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

write:

On 26 March 2001 at 03:15:00 UTC, a hard spectrum, high energy 
transient at high galactic latitude was detected and localized by 
HETE. Both the FREGATE and the WXM instruments detected the event. 
The burst triggered FREGATE in the 30-400 keV band.

The preliminary coordinates of the burst are R.A. = 11h50m59.11s, 
Dec. = -23°32'44" (J2000), derived from combining data from the WXM 
and Boresighted Optical Cameras. The statistical error radius in the 
WXM localization is 10 arcmin (90% confidence). In addition, we 
estimate a systematic error radius at present of 20 arcmin about this 
location. The spacecraft aspect was known to an accuracy of +/- 2 
arcmin (95% confidence) from the optical cameras, and will be 
improved.

The burst exhibited a multiple-peaked structure and lasted about 25 
seconds. The peak flux seen with FREGATE (6-30 keV) was ~1 Crab. The 
peak flux was significantly less in the WXM.

Follow-up observations of this GRB event are encouraged.

Additional information on GRB010326 (including light curves and the 
WXM error box), as well as the HETE mission, is available at:

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

Acronyms:
HETE=High Energy Transient Explorer
FREGATE=French Gamma Ray Telescope
WXM=Wide Field X-ray Monitor
SXC=Soft X-ray Camera

This message may be cited.

G. Ricker, D. Lamb, and S. Woosley on behalf of the HETE Science Team;

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

N. Kawai, M. Matsuoka, Y. Shirasaki, T. Tamagawa, A. Yoshida, E. 
Fenimore, M. Galassi, B. Preger, and  C. Graziani, on behalf of the 
HETE WXM Team;

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

write:

The systematic error radius for the HETE localization of GRB010326 by 
the WXM has been refined to 10 arcminutes. Further refinement is 
expected.

Follow-up observations of this GRB event are encouraged.

Additional information on GRB010326, as well as for the HETE mission, 
is available at:

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

Acronyms: HETE=High Energy Transient Explorer FREGATE=French Gamma 
Ray Telescope WXM=Wide Field X-ray Monitor SXC=Soft X-ray Camera

This message may be cited.

I have obtained CCD images centered on the position of GRB 010326,
11:50:59.1 -23:32:44 (J2000), with the Cerro Tololo Interamerican
Observatory 0.9-m reflector, on 2001 March 26 from 08:18 to 08:50 UT. A
Johnson V filter was used, for a total of 1800 sec of integration, with a
field of view of 13' x 13'.

A preliminary comparison of the CCD frames with the 2nd-generation red
Digitized Sky Survey images of the same field discloses no obvious new
objects.

Howard E. Bond, Space Telescope Science Institute

P.A. Price, T.S. Axelrod, B.P. Schmidt (RSAA, ANU), D.E. Reichart, J.S.
Bloom and D. Fox (Caltech) report on behalf of a larger international GRB
collaboration:

"We have observed the error-circle of the HETE-2 GRB 010324 with the
robotic 50-inch telescope at Mount Stromlo Observatory starting at 2001
Mar 26.45 UT (7.5 hours after the GRB). Our 5x300 sec images cover the
entire error box, and go fainter than the DSS-2 red plates.  From a 
preliminary visual comparison of our images with the DSS-2 plates, we do
not detect any obvious bright optical counterpart.

Further observations are planned."

This message may be cited.

A. Henden (USRA/USNO) reports on behalf of the USNO GRB team:

We have acquired preliminary BVRcIc all-sky photometry for
an 11x11 arcmin field centered at the HETE localization
for GRB010326 (GCN 1015
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 ) with the USNOFS 1.0-m telescope
on one marginally photometric night with poor seeing.  Stars
brighter than V=14 are saturated and should be used with care.
We have placed the photometric data on our anonymous ftp site:
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb010326a.dat
The current photometry has a potential external zero-point
error of about three percent.  The astrometry in this file
is based on linear plate solutions with respect to USNO-A2.0.
The internal errors are less than 100mas.
  Further calibration of this field will not be performed
unless an optical counterpart is discovered.