The Dayglow photometer which monitors the O(1D)630.0 nm thermospheric airglow emission, has been converted into a day-night photometer and was operated from Waltair (17.7 ¿N, 83.3 ¿E dip. Lat. 10.09 ¿N) during March 1998 as a part of the Indian Solar Terrestrial Energy Program (ISTEP) campaign. The first results on the day-night airglow measurements together with ionosonde data from the same location are scrutinized in the present exercise. The base height of the F-layer (h'F) showed a strong negative correlation with dayglow intensity similar to nighttime conditions and a new empirical relation (Barbier type) linking the F-region electron densities and the h'F with the dayglow intensity has been worked out highlighting the importance of chemical processes in OI 630.0 nm dayglow and its variabilities. ¿ 2001 American Geophysical Union