  We report the discovery by M. Linnolt on JD 2455665.7931 (UT 2011 April
14.29) of the sixth eruption of the recurrent nova T Pyxidis. This discovery
was made just as the initial fast rise was starting, so with fast notification
and response by observers worldwide, the entire initial rise was covered (the
first for any nova), and with high time resolution in three filters. The speed
of the rise peaked at 9 mag/day, while the light curve is well fit over only
the first two days by a model with a uniformly expanding sphere. We also report
the discovery by R. Stubbings of a pre-eruption rise starting 18 days before
the eruption, peaking 1.1 mag brighter than its long-time average, and then
fading back towards quiescence 4 days before the eruption. This unique and
mysterious behavior is only the fourth known anticipatory rise closely spaced
before a nova eruption. We present 19 timings of photometric minima from 1986
to February 2011, where the orbital period is fast increasing with
P/dot{P}=313,000 yrs. From 2008-2011, T Pyx had a small change in this rate of
increase, so that the orbital period at the time of eruption was
0.07622950+-0.00000008 days. This strong and steady increase of the orbital
period can only come from mass transfer, for which we calculate a rate of
1.7-3.5x10^-7 Mo/yr. We report 6116 magnitudes between 1890 and 2011, for an
average B=15.59+-0.01 from 1967-2011, which allows for an eruption in 2011 if
the blue flux is nearly proportional to the accretion rate. The
ultraviolet-optical-infrared spectral energy distribution is well fit by a
power law with flux proportional to nu^1.0, although the narrow ultraviolet
region has a tilt with a fit of \nu^{1/3}. We prove that most of the T Pyx
light is not coming from a disk, or any superposition of blackbodies, but
rather is coming from some nonthermal source.
