The Geometric Magnitude and Albedo for the Globe of Saturn

TL;DR

This study re-evaluates Saturn's geometric magnitude and albedo using spectrophotometry from a ring-plane crossing, providing revised values that improve agreement with previous research and refine phase angle corrections.

Contribution

It introduces a new analysis of Saturn's magnitude and albedo based on spectrophotometry during a ring-plane crossing, improving phase angle correction methods.

Findings

Revised albedo values generally agree with prior studies.

Significant differences found in some wavelength bands.

Improved phase angle correction enhances measurement accuracy.

Abstract

Saturn's geometric magnitude and albedo were determined by Mallama et al. (2017, Icarus 282, 19-33). That analysis depended largely on photometric data obtained when the ring system interfered with observations of the globe. In this study the magnitude and albedo are re-evaluated based on spectrophotometry obtained during a ring-plane crossing (Karkoschka, 1998, Icarus, 133, 134-146). A better correction for the illumination phase angle of Saturn's globe is also derived and it is applied to the spectroscopy. The resulting values for most of the 12 Johnson-Cousins and Sloan wavelength bands agree reasonably well with those reported by Mallama et al. but some significant differences are noted. The revised albedo value for the Rc band reduces the discrepancy with that inferred from the work of Dyudina et al. (2005, ApJ 618, 973-986).