HXMT卫星空间环境监测器及初步观测结果

Space Environment Monitor and Preliminary Results of HXMT Satellite

硬X射线调制望远镜(HXMT)卫星是中国首个专门进行天文探测的空间科学实验卫星,运行于高度约550 km、倾角约43°的低地球轨道.星载空间环境监测器为星上科学任务开展提供背景辐射实测资料.该监测器采用固体探测器望远镜系统和扇形阵列全新组合设计,可获取轨道空间高能质子和高能电子能谱、方向综合动态结果,给出更为全面的粒子辐射分布图像.初步探测结果显示,卫星运行轨道遭遇的带电粒子辐射集中分布在经度80°W-20°E,纬度0°-40°S的南大西洋异常区,粒子辐射在该区域表现出不同程度的方向差异分布,高能电子方向差异分布显著强于高能质子.2017年9月空间环境扰动期间,爆发的太阳质子事件并未对该轨道粒子辐射产生影响,而地磁活动导致该轨道穿越经度120°W-60°E,纬度40°-43°N的北美上空和经度60°-120°E,纬度43°-40°S的澳大利亚西南区域时遭遇增强粒子辐射影响,增强的粒子辐射表现出极强的方向分布.

Hard X-ray Modulation Telescope(HXMT) was Chinese first space astronomy satellite,which was launched into 550 km orbit with inclination of 43° in June 2017.The Space Environment Monitor on HXMT was designed to provide measurements of energetic protons and electrons.The detector is an all solid-state system that can make 16-directional flux measurements of electrons with energy≥200 keV and protons with energy≥1.5 MeV,and can also measure the differential energy spectra of electrons from 0.4 to>1.5 MeV and protons from 3 to 300 MeV with 7 channels separately from single direction.The detector can characterize particles distribution for detail especially in SAA which is important for low Earth orbit missions.The primary observations provide relative comprehensive particles global distributions,and demonstrate that particles radiation are mainly observed in SAA within longitude 80°W-20°E and latitude 0°-40°S,and electrons in SAA show stronger anisotropy than protons,the SEP occurred in September 2017 had no effect on the orbit,while the magnetic storm in early time before the SEP induced electrons enhancement in narrow region within longitude 120°W-60°E and latitude 40°-43°N over North America and longitude 60°-120°E and latitude 40°-43°S over South-West Australia.The electrons showed intensive anisotropy.