Observations of Gamma-Ray Afterglows with Wide-field Optical Telescope

我们用为东波计划建造的原型望远镜成功地获得了5度× 5度的宽视场图象。然而，由于HETE-2卫星的发射延迟了一年多，以及望远镜焦平面随温度变化的不稳定性，我们未能探测到γ射线暴的光学余辉。可用于机器人望远镜项目RIBOTS。此外，在这项研究中开发的技术检测未知的瞬态可以用于后续观测的伽玛暴在木曾天文台的宽视场的空气切伦科夫望远镜nov正在开发中，采用的知识throagb这项研究。一些研究人员报道了从伽玛暴中探测到超过100 GeV的高能量伽玛射线，但它们在统计上是相当差的探测。因此，确认伽玛暴的高能γ射线辐射是十分重要的。然而，普通切伦科夫望远镜的视场较小，需要一种大视场的新型望远镜。我们使用ASCA，lananese X射线卫星，得到的最重要的结果是检测到GRB 970828光谱中的发射，线状结构。我们发现这种结构可以解释为铁在barst源周围的辐射复合边，这与余辉光谱给出的红移是完全一致的。这表明了伽玛暴的富铁环境的存在，并提出了大质量星星坍缩的伽玛暴方案。

We bave successfulty obtained wide field images of 5degree times 5degrees using the prototype telescope built for the TONBO projed. However, we coald not detect any optical afterglow from the Gamma-Ray Burst <GRB) due to more than one-year delay of the laanch of tbe HETE-2 satellite which we planned to utilize for GRB Iocations, and umknown instability of the telescope focus plane depending on the temperature.The techniques and knowledge obtained throagh this research, for instance a method of the rapid transfer of GRB ioformation via Internet, cad be utilized in the project of robotic telescope, RIBOTS. Furtbermore, the techniqae developed in this research on detecting unknown transients can be employed in the follow-up obselvations of GRBs at the Kiso Observatony A wide-field-of-view Air Cherenkov telescope nov under development by our group employs the knowledge obtained throagb this research. Some researchers have reported the detection of very bigh energy gamma-rays, over 100 GeV, from GRBs while they were rather statistically poor detections. It is clearty important to confirm such high energy gamma-ray emissions from GRBs. Ordinary Cherenkov tetescopes, however, have only small field-of-view and there needs a new type telescope with large field-of-view.We studied X-ray afterglows of GRBs as well. The most important result we got using the ASCA, lapanese X-ray satetlite, is to detect a emission, line like structure in the spectrum of GRB970828. We show that this structare can be interpreted as a radidative recombination edge from irons around the barst source, wbich is fully consistent with the redshift given by the optical spectroscopy of the afterglow. Tnts iadicates tbe existence of iron-rich environment of GRBS and sports the GRB scenario of massive star collapse.