  We report a mass and rotational broadening (vsini) for the pulsating white
dwarf component of the WZ Sge type Dwarf Nova GW Lib based on high-resolution
VLT spectroscopy that resolves the MgII 4481A absorption feature. Its
gravitational redshift combined with white dwarf mass-radius models, provides
us with a direct measurement of the white dwarf mass of M_1 = 0.84 pm 0.02
M_sun. The line is clearly resolved and if associated with rotational
broadening gives vsini=87.0 pm 3.4 km/s, equivalent to a spin period of 97 pm
12s.
