We investigated the optical light curve of T Pyx during its 2011 outburst through compiling a database of Solar Mass Ejection Imager ( SMEI ) and AAVSO observations .
The SMEI light curve , providing unprecedented detail covering t =1.5-49 days post-discovery , was divided into four phases based on the idealised nova optical light curve ; the initial rise ( 1.5-3.3 days ) , the pre-maximum halt ( 3.3-13.3 days ) , the final rise ( 14.7-27.9 days ) , and the early decline ( 27.9 days - - ) .
The SMEI light curve contains a strongly detected period of 1.44 \pm 0.05 days during the pre-maximum halt phase .
These oscillations resemble those found in recent TNR models arising from instabilities in the expanding envelope .
No spectral variations that mirror the light curve periodicity were found however .
The marked dip at t \sim 22-24 days just before light curve maximum at t =27.9 days may represent the same ( shorter duration ) phenomenon seen in other novae observed by SMEI and present in some model light curves .
The spectra from the 2m Liverpool Telescope and SMARTS 1.5m telescope were obtained from t =0.8-80.7 and 155.1-249.9 days , covering the major phases of development .
The nova was observed very early in its rise where a distinct high velocity ejection phase was evident with derived V _ { ej } \sim 4000 km s ^ { -1 } initially .
A marked drop at t =5.7 days , and then a gradual increase occurred in derived V _ { ej } to stabilise at \sim 1500 km s ^ { -1 } at the pre-maximum halt .
Here we propose two different stages of mass loss , a short-lived phase occurring immediately after outburst and lasting \sim 6 days followed by a more steadily evolving and higher mass loss phase .
The overall spectral development follows that typical of a Classical Nova and comparison with the photometric behaviour reveals consistencies with the simple evolving pseudo-photosphere model of the nova outburst .
Comparing optical spectra to X-ray and radio light curves , weak [ Fe X ] 6375Ã emission was marginally detected before the X-ray rise and was clearly present during the brightest phase of X-ray emission .
If the onset of the X-ray phase and the start of the final decline in the optical are related to the cessation of significant mass loss , then this occurred at t \sim 90-110 days .