Ten Years of the Okayama Vector Magnetograph

• Published in: International Astronomical Union Colloquium 1993, Vol.141, p.180-183
• Main Authors: Makita, Mitsugu, Sakurai, Takashi, Shibasaki, Kiyoto, Koyano, Hisashi
• Format: Article
• Language: English
• ISSN: 0252-9211
• DOI: 10.1017/S0252921100029043

The vector magnetograph of the Okayama Astrophysical Observatory (Makita et al. 1985a,c) is equipped on the 65cm solar coude telescope with the 10m Littrow spectrograph. Results of observations are vector magnetograms, velocitygrams, maps of the broadband polarizations, maps of the magnetic lines of force, and maps of the electric currents. Their examples are given in figure 1. The data books, which give the vector magnetograms, have been published every year since 1983. Calibrations of the polarization degree and the overall accuracy were discussed (Makita et al. 1982, 1987; Makita and Li 1992). The accuracy of the polarization measurement is 10 −3 for the line observation and 10 −4 for the continuum observation. Conversion of the polarization degrees to the magnetic field vector has been tried by Sakurai (1987) with the use of the weak field theory and the observed magnetic field strength of sunspots. A simultaneous observation of the same active region was once made with the Sayan Observatory (Makita et al. 1985b). Distributions of the magnetic polarity were quite similar and azimuths of the magnetic field agreed very well.