  The GOLF resonant scattering spectrophotometer aboard SoHO has now provided
15 years of continuous high precision Sun-as-a-star radial-velocity
measurements. This length of time series provides very high resolution in the
frequency domain and is combined with very good long-term instrumental
stability. These are the requirements for measuring the low-l low-frequency
global oscillations of the Sun that will unlock the secrets of the solar core.
However, before the scientifically interesting gravity and mixed modes of
oscillation fully reveal themselves, a correction and calibration of the whole
data set is required. Here we present work towards producing a 15 year GOLF
data set corrected for instrumental ageing and thermal variation.
