“…Kulkarni (1976) presented a few nights of OI 557.7 nm emission from Thumba (8 • 33 N), India, wherein the minimum intensity was observed between 23:00 h and 02:00 h followed by an increase thereafter. Recently, Liu et al (2008b) observed the nocturnal behaviour of this emission feature to exhibit minimum and maximum, and found the emission to be larger in the early morning hours than in the early night. Several other investigators have reported this type of nocturnal variation of OI 557.7 nm intensity (Takahashi et al, 1977(Takahashi et al, , 1989(Takahashi et al, , 1998Petitdidier and Teitelbaum, 1979;Oznovich et al, 1995;Shepherd and McLandress, 1995;Zhang et al, 1998;Wiens et al, 1999;Buriti et al, 2001).…”