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 ( with V1500 Cyg , V533 Her , and T CrB ) 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 years .
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 \pm 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 - 3.5 \times 10 ^ { -7 } M _ { \odot } yr ^ { -1 } .
We report 6116 magnitudes between 1890 and 2011 , for an average B = 15.59 \pm 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 f _ { \nu } \propto \nu ^ { 1.0 } , although the narrow ultraviolet region has a tilt with a fit of f _ { \nu } \propto \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 .
We confirm the extinction measure from IUE with E ( B - V ) = 0.25 \pm 0.02 mag , although we find problems with all prior distance determinations and are left only with 1000 \lesssim D \lesssim 10000 pc .