  We present high speed photometric observations of the eclipsing dwarf nova IP
Peg taken with the triple-beam camera ULTRACAM mounted on the William Herschel
Telescope. The primary eclipse in this system was observed twice in 2004, and
then a further sixteen times over a three week period in 2005. Our observations
were simultaneous in the Sloan u', g' and r' bands. By phase-folding and
averaging our data we make the first significant detection of the white dwarf
ingress in this system and find the phase width of the white dwarf eclipse to
be 0.0935 +/- 0.0003, significantly higher than the previous best value of
between 0.0863 and 0.0918. The mass ratio is found to be q = M2 /M1 = 0.48 +/-
0.01, consistent with previous measurements, but we find the inclination to be
83.8 +/- 0.5 deg, significantly higher than previously reported. We find the
radius of the white dwarf to be 0.0063 +/- 0.0003 solar radii, implying a white
dwarf mass of 1.16 +/- 0.02 solar masses. The donor mass is 0.55 +/- 0.02 solar
masses. The white dwarf temperature is more difficult to determine, since the
white dwarf is seen to vary significantly in flux, even between consecutive
eclipses. This is seen particularly in the u'-band, and is probably the result
of absorption by disc material. Our best estimate of the temperature is 10,000
- 15,000K, which is much lower than would be expected for a CV with this
period, and implies a mean accretion rate of less than 5 times 10^-11 solar
masses per year, more than 40 times lower than the expected rate.
