First Season MWA EoR Power Spectrum Results at Redshift 7
  The Murchison Widefield Array (MWA) has collected hundreds of hours of Epoch
of Reionization (EoR) data and now faces the challenge of overcoming foreground
and systematic contamination to reduce the data to a cosmological measurement.
We introduce several novel analysis techniques such as cable reflection
calibration, hyper-resolution gridding kernels, diffuse foreground model
subtraction, and quality control methods. Each change to the analysis pipeline
is tested against a two dimensional power spectrum figure of merit to
demonstrate improvement. We incorporate the new techniques into a deep
integration of 32 hours of MWA data. This data set is used to place a
systematic-limited upper limit on the cosmological power spectrum of $\Delta^2
\leq 2.7 \times 10^4$ mK$^2$ at $k=0.27$ h~Mpc$^{-1}$ and $z=7.1$, consistent
with other published limits, and a modest improvement (factor of 1.4) over
previous MWA results. From this deep analysis we have identified a list of
improvements to be made to our EoR data analysis strategies. These improvements
will be implemented in the future and detailed in upcoming publications.
