Clustering of the SDSS DR7 main galaxy sample. I.

II/294), covering 6813 deg^2^. Galaxies are chosen to sample the highest mass haloes, with an effective bias of 1.5, allowing us to construct 1000 mock galaxy catalogues (described in Howlett et al. 2015MNRAS.449..848H), which we use to estimate statistical errors and test our methods.

We use an estimate of the gravitational potential to "reconstruct" the linear density fluctuations, enhancing the baryon acoustic oscillation (BAO) signal in the measured correlation function and power spectrum. Fitting to these measurements, we determine D_V_(z_eff_=0.15)=(664+/-25)(r_d_/r_d_, _fid_) Mpc; this is a better than 4 per cent distance measurement. This "fills the gap" in BAO distance ladder between previously measured local and higher redshift measurements, and affords significant improvement in constraining the properties of dark energy.