It is shown as a function of wavelength in the following figure.
All values are valid for blaze maximum wavelengths.
Away from the blaze maxima the efficiencies can be lower by a factor up to 2. Note that the CES fibre diameter corresponds to a circular aperture of 2 arcsec on the sky. Therefore, the actually achievable throughput depends strongly on conditions like seeing, wind, and centering of the star in the fibre. The displayed efficiencies are for excellent seeing below 1 arcsec. However, these measurements are preliminary as they were complicated by non-ideal meteorological conditions.