STEREO-A SECCHI HI Level 2 produced by UK Solar System Data Centre

STEREO-A SECCHI HI Level 2 FITS files produced by the UK Solar System Data Centre, calibrated and background subtracted. Images stored in FITS files with filenames such as "20140101_180501_24h1A_br11.fts". The meaning of the different parts of this filename is as follows:

* 20140101 is the observation date, 2014-01-01;
* 180501 is the observation time, 18:05:01 UT;
* 2 represents Level-2;
* 4 is a code for the data units, where 4=Dn/Sec/Pixel, b=Mean Solar Brightness (MSB), and t=S10. MSB \& S10 have the diffuse source correction applied;
* h1 or h2 for HI-1 or HI-2;
* A or B for STEREO-A or STEREO-B;
* br for Buffinton/RAL background subtracted--a full running window where the F-corona is computed as the mean of the lowest quartile of pixels;
* 11 is the length of the running window in days, usually either 01 or 11 for HI-1, and 03 or 11 for HI-2.

本数据集包含由英国太阳系数据中心（UK Solar System Data Centre）生成的STEREO-A SECCHI HI 2级FITS文件，所有文件均已完成定标与背景扣除处理。图像存储于FITS格式文件中，文件名示例为"20140101_180501_24h1A_br11.fts"，该文件名各组成部分的含义如下：
* 20140101：观测日期，对应2014年1月1日；
* 180501：观测时刻，对应世界时（UT）18时05分01秒；
* 2：数据等级为Level 2；
* 4：数据单位编码，其中4代表Dn/Sec/Pixel，b代表平均太阳亮度（Mean Solar Brightness，简称MSB），t代表S10。MSB与S10均已完成漫射源校正；
* h1或h2：分别对应HI-1或HI-2观测仪器；
* A或B：分别对应STEREO-A或STEREO-B探测器；
* br：代表Buffinton/RAL背景扣除算法，该算法采用全滑动窗口，将F日冕的亮度计算为像素最低四分位数的均值；
* 11：滑动窗口的时长（单位：天），HI-1通常取01或11，HI-2通常取03或11。