  The design, calibration, and performance of the first radial drift Time
Projection Chamber (TPC) are presented. The TPC was built and installed at the
CERES/NA45 experiment at the CERN SPS in the late nineties, with the objective
to improve the momentum resolution of the spectrometer. The upgraded experiment
took data twice, in 1999 and in 2000. After a detailed study of residual
distortions a spatial resolution of 340 um in the azimuthal and 640 um in the
radial direction was achieved, corresponding to a momentum resolution of Dp/p =
sqrt{(1% * p/GeV)^2 + (2%)^2}.
