UBV observations have been made jointly at three observatories for the recent eclipse of the long period atmospheric eclipsing binary star Zeta Aur in 1995-6. Observations covered successfully the phases before, during, and after the eclipse enable us to determine the accurate time of mid-eclipse and the duration of the totality. The hypothesis of the expansion of the K supergiant has been tested and the positive conclusion may be derived.

• SARAH NHA(Dept. of Astronomy and Atmospheric Science, Yonsei University)
• YONG-SAM LEE(Dept. of Astronomy and Space Science, Chungbuk University)