ABSTRACT 1 Institute of Space Science, National Central University, Chung-Li, Taiwan, ROC 2 Department of Physics, National Central University, Chung-Li, Taiwan, ROC * Corresponding author address: Prof. Lin-Ni Hau, Institute of Space Science, National CentralUniversity, Chung-Li, Taiwan, ROC; E-mail: lnhau@jupiter.ss.ncu.edu.tw doi: 10.3319/TAO.2007.18.4.843(AA) Worldwide ground observations of upper atmospheric airglow withparticular emphasis on the OI 557.7 and 630 nm emissions have been con-ducted since 1960s. This study reports the first ground observations ofOI 557.7 nm green line emission over the Taiwan area. For comparison, thebackground continuum at 530 nm was also measured by the same system.The experiments were conducted during the period of Aug - Dec, 2004 atvarious locations in Taiwan using a self-developed photometer instrument.Daily height integrated intensity of the night-time green line emission mayvary in the range of 80 - 210 Rayleighs and twilight enhancement is alsoidentified. The observational results may serve as a useful reference forfollow-up sounding rocket measurements of OI 557.7 nm airglow emissionover the Taiwan area.(Key words: Airglow, OI 5577, Taiwan area, Ground observation)1. INTRODUCTION