Gamma-ray Burst 010326B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN notice #1018
  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, 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 08:33:12 UTC (=30792s UT), a soft spectrum, high energy transient at high galactic latitude was detected and localized by HETE. (NB: This is the second GRB detected by HETE on 26 March 2001.)
  Both the WXM and the FREGATE instruments detected the event. The burst triggered FREGATE in the 6-120 keV band, at the 160ms timescale.
  The preliminary coordinates of the burst are R.A. = 11h24m23.36s, Dec. = -11o09'57", derived from combining data from the WXM and Boresighted Optical Cameras. The statistical error radius in the WXM localization is 18 arcmin (90% confidence). In addition, we estimate a systematic error radius at present of 10 arcmin about this location. The spacecraft aspect was known to an accuracy of +/- 30 arcsec (95% confidence) from the optical cameras, and will be improved.
  The peak flux seen with FREGATE (6-30 keV) was ~4 Crab; with WXM (2-25 keV), ~2 Crab. The burst duration was about 4 seconds.
  The high galactic latitude of the source, well away from the Galactic Bulge, and the shape of its spectrum suggest that it is a gamma-ray burst similar to those reported for "X-ray rich" GRBs by Heise et al (2001) from BeppoSAX observations.
  Follow-up observations of this unusual transient are encouraged.
  Additional information on the GRB010326B (including light curves), 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.
  

• GCN notice #1020
  P.A. Price, T.S. Axelrod, B.P. Schmidt (RSAA, ANU), and D.E. Reichart (Caltech) report on behalf of a larger international GRB collaboration:
  "We have observed the error-circle of the HETE-2 GRB 010326B with the robotic 50-inch telescope at Mount Stromlo Observatory starting at 2001 Mar 26.61 UT (6 hours after the GRB). Our 5x300 sec images cover the entire error box, and go fainter than the DSS-2 red plates, although the depth is severely affected in regions by the presence of a very bright star. From a preliminary visual comparison of our images with the DSS-2 plates, we do not detect any obvious bright optical transient."
  This message may be cited.
• GCN notice #1027
  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 GRB010326B (GCN 1018) 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/grb010326b.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. Note that there are several bright stars near or in this field, causing a few non-physical 'stars' to appear in the .dat file. Be careful to check your images to ensure that any selected stars are real. Further calibration of this field will not be performed unless an optical counterpart is discovered.
• astro-ph/0605570 from 22 May 2006
  Donaghy: HETE-2 Localizations and Observations of Four Short Gamma-Ray Bursts: GRBs 010326B, 040802, 051211 and 060121
  Here we report the localizations and properties of four short-duration GRBs localized by the High Energy Transient Explorer 2 satellite (HETE-2): GRBs 010326B, 040802, 051211 and 060121, all of which were detected by the French Gamma Telescope (Fregate) and localized with the Wide-field X-ray Monitor (WXM) and/or Soft X-ray Camera (SXC) instruments. We discuss eight possible criteria for determining whether these GRBs are "short population bursts" (SPBs) or "long population bursts" (LPBs). These criteria are (1) duration, (2) pulse widths, (3) spectral hardness, (4) spectral lag, (5) energy Egamma radiated in gamma rays (or equivalently, the kinetic energy E_KE of the GRB jet), (6) existence of a long, soft bump following the burst, (7) location of the burst in the host galaxy, and (8) type of host galaxy. In particular, we have developed a likelihood method for determining the probability that a burst is an SPB or a LPB on the basis of its T90 duration alone. A striking feature of the resulting probability distribution is that the T90 duration at which a burst has an equal probability of being a SPB or a LPB is T90 = 5 s, not T90 = 2 s, as is often used. All four short-duration bursts discussed in detail in this paper have T90 durations in the Fregate 30-400 keV energy band of 1.90, 2.31, 4.25, and 1.97 sec, respectively, yielding probabilities P(S|T90) = 0.97, 0.91, 0.60, and 0.95 that these bursts are SPBs on the basis of their T90 durations alone. All four bursts also have spectral lags consistent with zero. These results provide strong evidence that all four GRBs are SPBs.