  The 44.7 ms X-ray pulsar in the supernova remnant G12.82-0.02/HESS J1813-178
has the second highest spin-down luminosity of known pulsars in the Galaxy,
with E-dot=5.6e37 erg/s. Using the Green Bank Telescope, we have detected radio
pulsations from PSR J1813-1749 at 4.4-10.2 GHz. The pulse is highly scattered,
with an exponential decay timescale \tau longer than that of any other pulsar
at these frequencies. A point source detected at this position by Dzib et al.
in several observations with the Jansky Very Large Array can be attributed to
the pulsed emission. The steep dependence of \tau on observing frequency
explains why all previous pulsation searches at lower frequencies failed
(\tau~0.25 s at 2 GHz). The large dispersion measure, DM=1087 pc/cc, indicates
a distance of either 6.2 or 12 kpc according to two widely used models of the
electron density distribution in the Galaxy. These disfavor a previously
suggested association with a young stellar cluster at the closer distance of
4.8 kpc. The high X-ray measured column density of ~1e23/cm^2 also supports a
large distance. If at d~12 kpc, HESS J1813-178 would be one of the most
luminous TeV sources in the Galaxy.
