In this paper, we suggest a new referencing method for the array On-The-Fly(OTF) observations in radio astronomy. To reduce the baseline residual, we have proposed and evaluated a new referencing method which uses the source free regions in the observed frame as references. These new references have small Δt and Δx, the time and position differences between the source and the references, and the systematic problems w~re improved by using this new referencing method. The curved baseline residuals were straightened and the rms was reduced to 17 mK. This new referencing method is expected not only to make possible to take more stable data for the array OTF observation of external galaxies but also to save the observation and data reduction time.

• EUN JUNG CHUNG(Dept. of Astronomy, Yonsei University/Taeduk Radio Astronomy Observatory, KASI)
• HYORYOUNG KIM(Taeduk Radio Astronomy Observatory, KASI)
• MYUNG-HYUN RHEE(Yonsei University Observatory)