觀測太陽

C.L.Chan

另闢蹊途

來到鶴咀迴旋處做觀測太陽的還有阿Dee同好。他不用濾鏡，而在淘寶找到一台光譜儀，把它接上了望遠鏡及攝像機，就可以拍攝整個太陽光譜，同時用電腦選取五個狹窄波段，就可以同時得到五張不同波譜的太陽的單色光相片。

C.L.Chan

The spectroheliograph works like this :
You select a line, such as H-apha, or Ca-K
Then narrow down the image to about 50 nm, placing the line close to the middle.
Then, use a fast capture rate.
Allow the solar image to drift from east to west limb, at a carefully selected rate by adjusting the tracking rate of the equatorial mount.
after capturing the thousands of the same spectral line, the software will make a mosaic of them to give a complete solar image.
The key point is the scan rate