UTC时间、GPST、BDT、年积日之间相互转换的C#程序。 小程序，可用于时间系统转换、从IGS下载数据之前的时间查询。(A C# program of the conversion between UTC time, GPST, BDT, and day of year . A small program, can be used for time, system conversion, the time query before download data from IGS.)