T-63: Studying the interaction between the magnetic field of Saturn and Titan
The interaction between the magnetic field of Saturn and Titan got prime measuring time during Cassini's "T-63" flyby of Titan on Dec. 12, 2009. This was the Equinox mission's most opportune passage through the wake that the large moon creates as it plows through Saturn's magnetosphere.
The Cassini Plasma Spectrometer (CAPS) team took the lead on pointing at closest approach, allowing some fields, particles and wave instruments to take advantage of this special opportunity.
The T-63 encounter passed through Titan's wake and the "magnetotail" region, where Saturn's magnetic field lines drape into a comet-shaped structure around Titan. This opportunity was both similar and very complementary to the Voyager (November 1980 and August 1981) and Cassini T-9 (December 2005) encounters of Titan.
The encounter occurred near dusk in Saturn's magnetosphere, unlike Voyager (near noon) or T-9 (near midnight). This was the second of three opportunities for a CAPS Equinox Mission prime encounter.
The T-63 flyby was also designed to set up the correct orientation for the first ansa-to-ansa ring occultation.