BARREL 4A Ephemeris (EPHM) Geographic and Magnetic Coordinates, Level 2, 4 s Data

Geographic and Magnetic Coordinates: The ephemeris data products, which include the balloon epoch time, latitude, longitude, and altitude, are each returned from the payload once every 4s. Geographic coordinates are obtained from an onboard Global Positioning System, GPS, unit. Magnetic coordinates are derived by using the International Radiation Belt Environment Modeling, IRBEM, FORTRAN library.地理与地磁坐标：星历数据产品包含气球历元时刻、纬度、经度与海拔高度，每4秒由有效载荷传回一组数据。其中地理坐标由机载全球定位系统（Global Positioning System，GPS）设备获取；地磁坐标则通过国际辐射带环境模型（International Radiation Belt Environment Modeling，IRBEM）的FORTRAN库计算得到。