The rotational dynamics of Titan from Cassini RADAR images

•Cassini SAR images are correlated to track Titan rotation along time.•Evidence of a synchronous spin rate for Titan is reported.•A new spin pole location including precession-nutation terms is proposed.•Titan pole location is compatible with the occupancy of a Cassini State.•Results are compatible with the presence of a thin shell underlain by an ocean. Between 2004 and 2009 the RADAR instrument of the Cassini mission provided 31 SAR images of Titan. We tracked the position of 160 surface landmarks as a function of time in order to monitor the rotational dynamics of Titan. We generated and processed RADAR observables using a least squares fit to determine the updated values of the rotational parameters. We provide a new rotational model of Titan, which includes updated values for spin pole location, spin rate, precession and nutation terms. The estimated pole location is compatible with the occupancy of a Cassini state 1. We found a synchronous value of the spin rate (22.57693deg/day), compatible at a 3-σ level with IAU predictions. The estimated obliquity is equal to 0.31°, incompatible with the assumption of a rigid body with fully-damped pole and a moment of inertia factor of 0.34, as determined by gravity measurements.