  The Square Kilometre Array (SKA), currently under design, will be a
transformational facility for studying the Universe at centimetre and metre
wavelengths in the next decade and beyond. This paper provides the current best
estimate of the anticipated performance of SKA Phase 1 (SKA1), using detailed
design work, before actual on-sky measurements have been made. It will be
updated as new information becomes available. The information contained in this
paper takes precedent over any previous documents.
