Our aim is to derive a self-consistent age , distance and composition for the globular cluster 47 Tucanae ( 47 Tuc ; NGC104 ) .
First , we reevaluate the reddening towards the cluster resulting in a nominal E ( B - V ) = 0.03 \pm 0.01 as the best estimate .
The T _ { eff } of the components of the eclipsing binary member V69 is found to be 5900 \pm 72 K from both photometric and spectroscopic evidence .
This yields a true distance modulus ( m - M ) _ { 0 } = 13.21 \pm 0.06 ( random ) \pm 0.03 ( systematic ) to 47 Tuc when combined with existing measurements of V69 radii and luminosity ratio .
We then present a new completely self-consistent isochrone fitting method to ground based and HST cluster colour-magnitude diagrams and the eclipsing binary member V69 .
The analysis suggests that the composition of V69 , and by extension one of the populations of 47 Tuc , is given by [ Fe/H ] \sim - 0.70 , [ O/Fe ] \sim + 0.60 , and Y \sim 0.250 on the solar abundance scale of Asplund , Grevesse & Sauval .
However , this depends on the accuracy of the model T _ { eff } scale which is 50-75 K cooler than our best estimate but within measurement uncertainties .
Our best estimate of the age of 47 Tuc is 11.8 Gyr , with firm ( 3 \sigma ) lower and upper limits of 10.4 and 13.4 Gyr , respectively , in satisfactory agreement with the age derived from the white dwarf cooling sequence if our determination of the distance modulus is adopted .