A new imaging system of the corona at Norikura

A new imaging system of the coronal green line (Fe XIV 5303 Angstrom) was c onstructed at the Norikura Solar Observatory. The system consists of a 10-c m coronagraph, a tunable Lyot filter, and a cooled CCD camera. The transmis sion curve of the Lyot filter can be modulated by two liquid-crystal variab le retarders. This scheme provides quick wavelength tuning and efficient su btraction of sky background. Two-dimensional distributions of the intensity and Doppler shift of the coronal green line can be obtained within 30 seco nds with accuracies of better than 10(-6)I(.) and 1 km s(-1). Regular opera tion was started in 1997 September. The aim of the new system is to investi gate plasma motions associated with the magnetic field reconnection and wav es in the solar corona.