The filter wheel preceding the dielectric beam splitter in each FGS contains five 42mm diameter slots. Four of these slots house filters-F550W, F583W, F605W and F5ND-while the fifth slot houses the PUPIL stop. This stop helps restore the S-Curve morphology throughout the FOV of each FGS by blocking out the outer 1/3 perimeter of the spherically aberrated primary mirror. The filter selection for each FGS, their central wavelengths, and widths are listed in the table below. The transmission curves (filters and PUPIL) and PMT efficiencies are given in the figures below.
Figure 1. FGS1r Filter Transmission Curves:
Figure 2. PMT Efficiency: