FOCAS grism efficiencies
The following plots show the efficiencies of the four FOCAS grisms. They should help you to decide which grisms are most sensitive for your specific needs.
75 lines/mm grating
150 lines/mm grating
300 lines/mm gratings
Echelle grism (175 gr/mm)
Efficiency measurements are not available for the VPH grisms. Instead, total efficiency (including atmosphere, telescope and FOCAS) obtained on clear nights are shown below.
