A dataset containing wavelengths at a 5 nm interval (300 nm to
830 nm) and the corresponding spectral energy irradiance normalized to 1 at
560 nm. Spectrum approximates typical, domestic, tungsten-filament lighting
and 'corresponds' to a black body a 2856 K. CIE standard illuminant A is
intended to represent typical, domestic, tungsten-filament lighting.
Original data from http://files.cie.co.at/204.xls downloaded on
2014-07-25 The variables are as follows: