SIMBAD references

We use recently updated globular cluster distances to estimate the distance to the Galactic Centre, finding 7.4±0.2{verbar}stat±0.2{verbar}sys kpc from symmetry considerations, including a trough at the Galactic Centre and peaks denoting the position of the bar. We recalibrate the red clump magnitude from Hipparcos stars, finding a skew distribution and a significant difference between peak and mean magnitudes. We find an estimate from stars in the periphery of the bulge using 2MASS, R0 = 7.5±0.3 kpc, in agreement with the figure from the halo centroid. We resolve discrepancies in the literature between estimates from the red clump. Our results are consistent with those found by different methodologies after taking systematic errors into account.