Spectral radiance in the s20-range and luminance of the clear and overcast night sky

The spectral radiance of the night sky was investigated in the wavelength range from 0.40 microm to 0.80 microm.A series of measurements was taken in the Austrian Alps in 1968. Statistical reductions were made for the total data assembly as well as for data groups with different types of night sky cover, for moonless nights, and for nights with moon. The mean spectral radiance and the standard deviation in the above mentioned wavelength range are presented and discussed together with the distribution functions of the spectral radiance at 0.40 microm, 0.45 microm, 0.5577 (OI) microm, and 0.80 (OH) microm, of the photopic and scotopic luminances and of the S20 radiance. Finally the correlation coefficients regarding each pair of photopic, scotopic, and S20 responses were calculated together with the corresponding regression coefficients. The correlation coefficients are almost equal to unity.