AI intro: Stellar occultations have been used extensively by the Cassini UVIS team to study Saturn’s rings and icy satellites. In a stellar occultation, a star passes behind the rings or a satellite as seen from the spacecraft, and the UVIS instrument measures the drop in starlight as a function of time and wavelength. This technique allows for high-resolution measurements of the ring structure, particle size distribution, and composition, as well as the detection of tenuous atmospheres around icy moons.
The UVIS instrument has a dedicated occultation slit that is 800 μm wide, which provides a balance between spectral resolution and signal-to-noise ratio. The occultation slit is used in conjunction with the FUV channel, which covers the wavelength range from 1100 to 1900 Å. The EUV channel is not typically used for stellar occultations due to its lower sensitivity and higher background noise.
The data from stellar occultations are stored in the same PDS format as other UVIS observations, with some additional metadata to describe the geometry of the occultation event. The data can be processed using standard UVIS calibration procedures, with some modifications to account for the rapid changes in signal during the occultation.
For more detailed information on how to analyze and interpret stellar occultation data from Cassini UVIS, please refer to Chapters UVIS Calibration, Rings Spectroscopy Data Reduction, and {ref}`sec:ref_spec_icy_moon