GRB 010921: Localization and observations by the high energy transient explorer satellite

G. Ricker, K. Hurley, D. Lamb, S. Woosley, J. L. Atteia, N. Kawai, R. Vanderspek, G. Crew, J. Doty, J. Villasenor, G. Prigozhin, G. Monnelly, N. Butler, M. Matsuoka, Y. Shirasaki, T. Tamagawa, K. Torii, T. Sakamoto, A. Yoshida, E. FenimoreM. Galassi, T. Tavenner, T. Donaghy, C. Graziani, M. Boer, J. P. Dezalay, M. Niel, J. F. Olive, G. Vedrenne, T. Cline, J. G. Jernigan, A. Levine, F. Martel, E. Morgan, J. Braga, R. Manchanda, G. Pizzichini, K. Takagishi, M. Yamauchi

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


On 2001 September 21 at 05:15:50.56 UT, the French Gamma Telescope (FREGATE) on the High Energy Transient Explorer (HETE) detected a bright gamma-ray burst (GRB). The burst was also seen by the X-detector on the Wide-field X-ray Monitor (WXM) instrument and was therefore well localized in the X-direction; however, the burst was outside the fully coded field of view of the WXM Y-detector, and therefore information on the Y-direction of the burst was limited. Cross-correlation of the HETE and Ulysses time histories yielded an Interplanetary Network (IPN) annulus that crosses the HETE error strip at an ∼45° angle. The intersection of the HETE error strip and the IPN annulus produces a diamond-shaped error region for the location of the burst having an area of 310 arcmin2. Based on the FREGATE and WXM light curves, the duration of the burst is characterized by t90 = 34.2 s in the WXM 4-25 keV energy range, and 23.8 and 21.8 s in the FREGATE 6-40 and 32-400 keV energy ranges, respectively. The fluence of the burst in these same energy ranges is 4.8 × 10-6, 5.5 × 10 -6, and 11.4 × 10-6 ergs cm-2, respectively. Subsequent optical and radio observations by ground-based observers have identified the afterglow of GRB 010921 and determined an apparent redshift of z = 0.450.

Original languageEnglish (US)
Pages (from-to)L127-L130
JournalAstrophysical Journal
Issue number2 II
StatePublished - Jun 1 2002
Externally publishedYes


  • Gamma rays: bursts

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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