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)

VPH grisms

Efficiency measurements are not available for the VPH grisms. Instead, total efficiency (including atmosphere, telescope and FOCAS) obtained on clear nights are shown below.