A discussion on the maximum aperture of a ground-based optical telescope

Because of the limitations both from the slit width and the slit length of the spectrograph used in high resolution work, the efficiency of a telescope, with an aperture between D₀ = 9m and D′₀ = 55m, will be no better than that of a telescope with aperture D₀. D₀ can be identified as the maximum aperture of a ground-based telescope.