  Centaurus (Cen) A represents one of the best candidates for an isolated,
compact, highly polarized source that is bright at typical cosmic microwave
background (CMB) experiment frequencies. We present measurements of the 4
degree by 2 degree region centered on Cen A with QUaD, a CMB polarimeter whose
absolute polarization angle is known to 0.5 degrees. Simulations are performed
to assess the effect of misestimation of the instrumental parameters on the
final measurement and systematic errors due to the field's background structure
and temporal variability from Cen A's nuclear region are determined. The total
(Q, U) of the inner lobe region is (1.00 +/- 0.07 (stat.) +/- 0.04 (sys.),
-1.72 +/- 0.06 +/- 0.05) Jy at 100 GHz and (0.80 +/- 0.06 +/- 0.06, -1.40 +/-
0.07 +/- 0.08) Jy at 150 GHz, leading to polarization angles and total errors
of -30.0 +/- 1.1 degrees and -29.1 +/- 1.7 degrees. These measurements will
allow the use of Cen A as a polarized calibration source for future millimeter
experiments.
