关于天格¶
天格计划（Gamma Ray Integrated Detectors，或GRID），即空间分布式引力波暴电磁对应体探测网，是利用纳卫星搭载的、覆盖全天的伽马射线暴探测网络，可与地面引力波探测器aLIGO、Virgo等协同工作，实现对中子星并合引起的引力波暴电磁对应体的全天监测和高精度定位。
本项目的主要科学目标是寻找中子星并合导致的引力波暴在高能电磁波段（伽马射线波段）的对应体。由于地面引力波探测器灵敏度的局限性，只能探测到约200Mpc以内的中子星并合事件。这个距离内的伽马暴短暴发生率可能极低，但一旦喷流对准地球，暴发流强将极大。因此，这是一个针对明亮稀有事例的探测。受地球遮挡，低轨卫星只能覆盖约60%的天区。基于此，我们提出了天格计划，利用多颗纳卫星在约500-600公里的低地球轨道组成伽马射线暴探测网，建成全天4π立体角灵敏的探测网络，并利用不同探测器之间伽马暴信号的时间延迟和流强差异，对暴源方向进行精度小于10°的定位。
目前，天格计划共计发射纳卫星载荷共8个，仍在轨运行载荷有6个。本网站公开天格计划纳卫星探测器的观测数据，可根据天格数据进行伽马暴相关科学分析。
About GRID
GRID (Gamma-Ray Integrated Detectors) is a student project designed to use multiple gamma-ray detectors carried by nanosatellites (NanoSat), forming a full-time and all-sky gamma-ray detection network to monitor the transient gamma-ray sky in the multi-messenger astronomy era. A compact NanoSat gamma-ray detector has been designed and implemented for GRID, including its hardware and firmware, with considerable contribution from undergraduate students. The detector employs four GAGG:Ce scintillators coupled with four silicon photomultiplier (SiPM) arrays to achieve a high detection efficiency of gamma rays between 10 keV and 2 MeV with low power and small dimensions. The first NanoSat payload GRID-01 was launched on 29 October 2018 as a pathfinder, and the GRID-02 NanoSat was launched on 6 November 2020, carried out stable long-term scientific observations. So far, 8 GRID NanoSat detectors have been launched, and successfully observed the first dozens of GRBs, including the GRB 210121A. The detector design and the in-orbit results, as well as our educational experience during this, are given in this talk.
