  The Murchison Widefield Array is a low frequency (80 - 300 MHz) SKA
Precursor, comprising 128 aperture array elements distributed over an area of 3
km diameter. The MWA is located at the extraordinarily radio quiet Murchison
Radioastronomy Observatory in the mid-west of Western Australia, the selected
home for the Phase 1 and Phase 2 SKA low frequency arrays. The MWA science
goals include: 1) detection of fluctuations in the brightness temperature of
the diffuse redshifted 21 cm line of neutral hydrogen from the epoch of
reionisation; 2) studies of Galactic and extragalactic processes based on deep,
confusion-limited surveys of the full sky visible to the array; 3) time domain
astrophysics through exploration of the variable radio sky; and 4) solar
imaging and characterisation of the heliosphere and ionosphere via propagation
effects on background radio source emission. This paper will focus on a brief
discussion of the as-built MWA system, highlighting several novel
characteristics of the instrument, and a brief progress report (as of June
2012) on the final construction phase. Practical completion of the MWA is
expected in November 2012, with commissioning commencing from approximately
August 2012 and operations commencing near mid 2013. A brief description of
recent science results from the MWA prototype instrument is given.
