The distance to the Galactic centre: Globular clusters and SEKBO RR Lyrae survey stars

One of the long-standing problems in astronomy is the exact distance of the Sun from the Galactic centre, r₀. The recent estimates yield the distances within the wide range 7.5-8.9 kpc. We use the maximum likelihood statistical method originally suggested by Rastorguev et al. in the middle of 1990s to derive r₀ from the space distribution of halo objects. The latest edition of the Harris catalogue of 157 globular clusters and the Southern Edgewort-Kuiper Belt Object (SEKBO) survey catalogue of 2016 RR Lyrae stars by Keller et al. are exploited. Space distribution modelling of clusters yields r₀ = 7.0 ± 0.3 kpc or r₀ = 7.3 ± 0.3 kpc, depending on one's assumptions about the object metallicity, the 'Oosterhoff dichotomy'. It is impossible to understand which value of r₀ is the most probable. Moreover, such a solar distance is systematically smaller than currently accepted values. A more accurate estimate by using the RR Lyraes leads persuasively to r₀ = 8.1 ± 0.2 kpc.