Cassini captured this Titan, Rhea (lower left) and Mimas mutual event on March 25, 2015 with its narrow-angle camera. A very faint ring (G ring?) that is almost undetectable unless the photo is viewed in darkness runs horizontally between Rhea's upper limb and Mimas' disk. Several faint stars are also visible.
Viewing geometry: Distance to Titan: 4.35 million km Distance to Rhea: 2.63 million km Distance to Mimas: 3.03 million km Phase angle: 142°