STUDY SUMMARY - IPMU

SUMMARY REPORT
WIDE FIELD FIBER-FED OPTICAL
MULTI-OBJECT SPECTROMETER (WFMOS)
Table 4.1-1: Throughput budget for Dark Energy and Galactic Archaeology surveys. The spectrograph efficiency differs for the two
survey types because of differences in the order sorting filter. The bottom line throughput number for the Galactic Archaeology
surveys reflects this difference. The throughput does not include optical coupling at the fiber entrance as this depends on seeing and
the target (e.g. galaxy size). These factors are accounted for separately in exposure time calculations. The entry for the WFC
vignetting is an average across the field.
Component
Wavelength (nm)
420 440 550 640 790 970
Throughput
Atmosphere 0.83 0.83 0.89 0.9 0.9 0.9
Secondary Obscuration 0.95 0.95 0.95 0.95 0.95 0.95
Primary Reflectance 0.9 0.9 0.9 0.9 0.85 0.85
WFC Throughput 0.88 0.88 0.88 0.88 0.88 0.82
WFC Vignetting 0.83 0.83 0.83 0.83 0.83 0.83
Uncorrected Atmospheric Dispersion 0.995 0.995 0.995 0.995 0.995 0.995
Corrector Plate Throughput 0.98 0.98 0.98 0.98 0.98 0.98
Misalignment between WFMOS/HPFU 0.98 0.98 0.98 0.98 0.98 0.98
Obscuration of pupil by Metrology System 0.995 0.995 0.995 0.995 0.995 0.995
Obscuration of pupil by Spectral Cal System 0.995 0.995 0.995 0.995 0.995 0.995
Fiber Positioners 0.89 0.89 0.89 0.89 0.89 0.89
Fiber System 0.55 0.55 0.61 0.66 0.68 0.68
Spectrograph 0.689 0.689 0.689 0.689 0.689 0.689
CCD QE 0.895 0.931 0.957 0.973 0.997 0.931
DE Instrument throughput 0.29 0.29 0.34 0.38 0.40 0.37
GA Instrument throughput 0.23 0.25 0.29 0.32 0.34 0.26
DE Total throughput 0.15 0.15 0.19 0.21 0.21 0.18
GA Total throughput 0.12 0.13 0.16 0.18 0.18 0.13
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