SDO/HMI Continuum Data

The HMI continuum data refers to map of the continuum intensity of the solar spectrum in the region of the Fe I absorption line at 6173 Å on the surface of the sun.

HMI samples the Fe I absorption line at 6173.3 Å at six points. Assuming that the "pure" solar Fe I line profile is a Gaussian, and the HMI filter filter transmission profiles are delta functions, the first and second Fourier coefficients of the of the Fe I line can be calculated and an estimate of the Doppler Velocity can be made. An estimate (proxy) for the continuum intensity Ic is obtained by "reconstructing" the solar line from the estimates of the Doppler shift λo, the linewidth σ, and the linedepth Id. More details can be found at http://jsoc.stanford.edu/relevant_papers/observables.pdf.

HMI连续谱数据指的是太阳表面铁I吸收线（位于6173 Å）区域太阳光谱连续强度的图谱。HMI在六个点上对6173.3 Å处的铁I吸收线进行采样。在假设“纯净”的太阳铁I线轮廓为高斯函数，以及HMI滤波器的滤波器透射轮廓为δ函数的前提下，可以计算铁I线的首项和第二项傅里叶系数，并据此估算多普勒速度。通过“重构”太阳线，基于多普勒移位λo、线宽σ和线深度Id的估算，获取连续强度Ic的估计（代理值）。更多详细信息请参阅http://jsoc.stanford.edu/relevant_papers/observables.pdf。