  The Sunspot Number, created by R.Wolf in 1849, provides a direct long-term
record of solar activity from 1700 to the present. In spite of its central role
in multiple studies of the solar dynamo and of the past Sun-Earth relations, it
was never submitted to a global critical revision. However, various
discrepancies with other solar indices recently motivated a full re-calibration
of this series. Based on various diagnostics and corrections established in the
framework of several Sunspot Number Workshops and described in Clette et al.
2014, we assembled all corrections in order to produce a new standard version
of this reference time series. In this paper, we explain the three main
corrections and the criteria used to choose a final optimal version of each
correction factor or function, given the available information and published
analyses. We then discuss the good agreement obtained with the Group sunspot
Number derived from a recent reconstruction. Among the implications emerging
from this re-calibrated series, we also discuss the absence of a rising secular
trend in the newly-determined solar cycle amplitudes, also in relation with
contradictory indications derived from cosmogenic radionuclides. As conclusion,
we introduce the new version management scheme now implemented at the World
Data Center - SILSO, which reflects a major conceptual transition: beyond the
re-scaled numbers, this first revision of the Sunspot Number also transforms
the former locked data archive into a living observational series open to
future improvements.
