A Method for Improving the Observational Device of the Magnetic Field of A Sunspot at the Yunnan Observatory

A method for improving the observational device of the magnetic field of a photospheric sunspot is proposed for the two-dimensional multi-waveband solar spectrograph at the Yunnan Observatory. The improved device has been put into operation and the observed results shows that: (1) The observation of the magnetic field of a sunspot (A line of Fe Ⅰ 6173Å which is sensitive to the magnetic field is used) can be carried out quasi-synchronously (or quasi-simulta-neously) with that of the scanning photograph of the multi-waveband two-dimensional solar spectrograph. (2) The split distance between the gravity centers of the lines which are sensitive to the magnetic fields indicates the real strength of the longitudinal magnetic field at the corresponding point in the solar disc. (3) The measurable value of the magnetic field is at least about 100 Gauss. (4) The data obtained with the device can be treated rapidly with a computer.