HETE FOV

1. Attitude Control Cross section perpendicular to Crab drift direction Camera X counters Y counters Time 3 min SXC TOP VIEW 0.5 - 14 keV Boresight Camera • Imaging ~10” • Spectroscopy 2 39"/pix. WXM 5.5x5.5 deg 2 - 25 keV • Imaging ~10’ • Spectroscopy Pulse Profile (2 cycles are shown) FREGATE 6 - 400 keV •Trigger 2 88"/pix. •Spectroscopy 12.6x12.6 deg WXM light curve 30sec HETE FOV o +60 o +30 o Dec 0 o -30 o -60 h h h h h 0 6 12 18 24 RA In-orbit Performance of the Wide-field X-ray Monitor on board the High Energy Transient Explorer 2 N. Kawai, A. Yoshida, T. Tamagawa (RIKEN), M. Matsuoka, Y. Shirasaki (NASDA) M. Yamauchi (Miyazaki Univ.), E.E. Fenimore, and M. Galassi (LANL) on behalf of the HETE-2 science mission team High Energy Transient Explorer 2 (HETE-2) reports the coordinates of Gamma-ray burst (GRB) more quickly and accurately than that we have ever had. X-ray detectors of HETE-2 determine the GRB position with an accuracy of 10 arcmin (10 arcsec for the best case) on board, and report them to the world within 10 sec via the internet. By combining the HETE-2 GRB alerts with follow-up observations, we can study GRBs from just after the burst where the most informative phase of the GRBs. The wide-field X-ray monitor (WXM), which has a field of view of 60deg x 60deg, is the key instrument for the HETE-2 localization. It is important to study the performance of the WXM in orbit for reporting the GRB position with good accuracy. In-orbit WXM calibration with the Crab nebula • Coded-mask image as a function of time We measured Crab position with WXM at a few hundred points distributed in its field of view. The data were compare to the positions measured by the optical cameras which provide more accurate position information than WXM. • Energy spectrum • Power spectrum density • weight 124 kg • hight 89 cm • width 66 cm Fundamental(29.83 Hz: P=33.52 ms) • WXM : 1D proportional counters + • coded-masks • altitude 590-630 km • equatorial orbit • pointing to anti-solar direction Data: Dec. 22, 2000 256 seconds duration GRB detection by HETE : GRB010213 Launched at 4:45pm October 9, 2000 (JST) GRB010213 HETE Burst Alert Network When a GRB is detected by HETE, a summary of the collected data send to the series of 12 burst alert stations distributed around the equator in 10 sec after the burst. These data is forwarded to MIT and distributed to the ground observers via GRB Coordinate Network (GCN). HETE orbit and the burst alert stations A red circle shows the coverage area of a burst alert station. RIKEN provides Singapore primary / burst alert station and Palau one. We issued the HETE’s first GCN report (GCN #934) on February 13. The coordinates of the burst are derived from combining data from the WXM and Boresighted Optical Cameras. The statistical error radius in the WXM localization is 3.5 arcmin (95%CL). In addition, we have an unresolved systematic error of a fraction of degree, and it will be improved. The high galactic latitude of the source, well away from the Galactic Bulge, and the shape of its light curve suggest that it is a gamma-ray burst with a very unusual spectrum, perhaps similar to those reported for "X-ray rich" GRBs by Heise et al (2001) from BeppoSAX observations. Conceivably, it could instead be a nearby X-ray burst source. A catalog search of the WXM error circlerevealed no correspondence with known globular sources, cataclysmic variables, low mass X-ray binaries, or flare stars. Singapore primary station and a 1.8m parabolic antenna Palau burst alert station