We report the development of a semi-VLBI observation system operating at 21 cm and present the measurement of visibility function toward the sun using this system. The system consists of two 2.3 meter antennas with a maximum separation of 35 meter, a conventional high speed data acquisition system, and a set of programs for software correlation. Since two local oscillators of receiver modules are independent, data had to be fringe-fitted to yield the visibility amplitude. It is found that the visibility amplitude decreases and then bounces back as baseline increases. We confirm that solar disk with brighter limb best explains the measured visibility amplitude.

• Song-Hun Kang(Korea Advanced Institute of Science and Technology)
• Young-Soo Shin(School of Earth and Environmental Sciences, SNU)
• Jin-Su Kim(School of Earth and Environmental Sciences, SNU)
• Jung-Hyun Ahn(Gyeonggi Science High School)
• Sul-Gi Lee(Gyeonggi Science High School)
• Myeong-Keun Jee(Gyeonggi Science High School)
• Heui-Jeong Kang(Gyeonggi Science High School)
• Hyo-Uk Kim(Gyeonggi Science High School)
• Hyun-Woo Kang(FPRD, School of Physics and Astronomy, SNU)
• Yong-Sun Park(FPRD, School of Physics and Astronomy, SNU)