Study of Gamma-Ray Bursts and Afterglows using HETE-2 Satellite

HETE-2卫星是一颗小型天文卫星，主要用于研究伽马射线暴（GRBs）。它于2000年10月9日发射升空。在5月至8月期间，HETE-2测试了仪器的功能并调整了机载软件后，于2001年仲夏开始了稳定的观测。卫星操作、维护科学仪器和快速分析由麻省理工学院任务操作中心的HETE-2操作团队与日本团队、RIKEN、AGU、东京工业大学和NAO的工作人员和研究生一起进行。除了x射线探测器上四分之一的计数器外，这三种科学仪器都在正常工作，该探测器的功能可能是由于遇到小型空间碎片而发生事故而丧失的。HETE-2成功定位GRB位置，并及时向地面观测者发送通知，延迟几十秒，比以前的实验（如BeppoSAX）快了三个数量级。因此，早期余辉已经被观测到，并且发现一些在时间上表现出非常快的衰减，而另一些在它们的早期光曲线上表现出复杂的结构。在GRB030329余辉的光谱中发现了Ic型超新星的光谱成分。这为grb和SNs之间的关联提供了令人信服的证据。HETE-2携带的科学仪器都对10 keV以下的x射线敏感，因此检测到许多富x射线grb和x射线闪光。HETE-2积累的观测数据表明，这些现象具有相似的性质，因此具有相同的天体物理起源。HETE-2还在厄瓜多尔上空赤道附近发现了一个未知的高密度带电粒子区，该区域显示出与太阳活动相关的时间变化。

The HETE-2 satellite is a small astronomical satellite for mainly studying gamma-ray bursts (GRBs). It was launched on 9^<th> of October in 2000. After having tested functioning of the instruments and adjusted the on-board software during May through August, HETE-2 began steady observations in midsummer of 2001. The satellite operation, maintaining the scientific instruments and quick-look analyses are conducted by the HETE-2 operation team at Mission Operation Center in MIT together with the Japanese team, staffs and graduate students in RIKEN, AGU, Tokyo Tech and NAO. The three scientific instruments are normally working except for one out of four counters in the X-ray detector, of which function was lost by an accident perhaps due to an encounter with a small space debris.HETE-2 successfully localizes GRB locations and sends prompt notifications to ground observers with delay of a few tens of seconds which is three orders of magnitude faster than that of previous experiments such as BeppoSAX. Thereby early afterglows have been observable and it is found that some show very quick decay in time and others display complex structure in their early light curves.Remarkable observational result recently made is that the discovery of a spectral component of Type Ic Supernova in optical spectra of GRB030329 afterglow. This results in compelling evidence of association between GRBs and SNs.The scientific instruments carried by HETE-2 are all sensitive to X-ray below 10 keV, and hereby many X-ray Rich GRBs and X-ray Flashes are detected. The observational data accumulated by HETE-2 suggest that these phenomena have similar properties and thereby a same astrophysical origin.HETE-2 also discovered an unknown zone of high density charged particles around the equator above Ecuador which displayed time variability correlated with the solar activity.