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Atlas of Statistical Moments of UVIS Stellar Occultation Data of Saturn’s Rings

Presentation #407.08 in the session “Planetary Rings: Theory and Observations”.

Published onOct 03, 2021
Atlas of Statistical Moments of UVIS Stellar Occultation Data of Saturn’s Rings

The Cassini Ultraviolet Imaging Spectrograph (UVIS) High Speed Photometer (HSP) recorded over 270 full or partial occultations of stars by Saturn’s rings. The ring structure in these data is usually represented by the optical depth which is derived from the mean, or the first moment, of the data. Previous work has shown that information on particle or clump sizes can be retrieved from the second moment, or variance, of the data (Showalter and Nicholson 1990, Icarus, 87, 285; Colwell et al. 2018, Icarus, 300, 150). The presence of localized openings or “ghosts” in the rings can be detected from analysis of the third moment, or skewness, of the data (Green et al. 2019, Fall AGU #P23C-3506). Here we present a standardized pictorial atlas of these moments, and the fourth moment (kurtosis) for the UVIS ring stellar occultations. These will be delivered to the NASA Planetary Data System in tabular format. Moments are calculated from data in radial bins of 10 km, corresponding to about 1000 data points in a typical occultation. We also calculate the auto-correlation of the data as a function of offset, or lag, and present the lag for the autocorrelation to reach zero, which provides another measure of the radial scale of structure in the rings.


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