The large distance between Earth and other planetary systems makes it so that exoplanets appear as point sources to our telescopes. This is in stark contrast to the appearance of our own solar system planets, which range in angular diameter from a few arcseconds to arcminutes. Their relatively large projected size on the sky allows for detailed analysis of planetary features such as rings, atmospheric and cloud features, and more. The Planet as Exoplanet Analog Spectrograph (PEAS) instrument at Lick Observatory is designed to simulate exoplanet observations and analysis techniques using disk integrated observations of the solar system planets. PEAS uses an integrating sphere to spatially scramble the light from the planet and take a spectrum of the entire visible surface. PEAS observations of solar system planets can then be used as benchmarks for testing and validating exoplanet observations and atmospheric models. In this work, we model the throughput of the PEAS instrument, including the telescope, integrating sphere, and spectrograph components. We are able to reproduce a PEAS spectrum to within a factor of 10. We then model the throughput with possible upgrades to the system and determine which new components would produce the best efficiency.
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