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P. Mst, . Jnc, C. Ljs, M. Smb, . Rnc et al., We thank Tilmann Denk for the color mosaic image processing that created Fig. 1a. Funding: MST acknowledges funding from the NASA Cassini Data Analysis program (NNX16AI33G) and the Cassini project. The work of LJS, SMB, ED, and RM was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA: government sponsorship acknowledged. CDM and NJC thank the Science and Technology Facilities Council of the UK (Grant No. ST/P000622/1) for financial support, Acknowledgements: We thank the Cassini project, the science planners, and the instrument teams for making these observations possible

, 2.020±0.088 0.216±0.054 270-008-H