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The spectroscopic Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) galaxy sample represents the final set of galaxies observed using the original SDSS target selection criteria. We analyse the clustering of galaxies within this sample, including both the luminous red galaxy and main samples, and also include the 2-degree Field Galaxy Redshift Survey data. In total, this sample comprises 893 319 galaxies over 9100 deg². Baryon acoustic oscillations (BAO) are observed in power spectra measured for different slices in redshift; this allows us to constrain the distance–redshift relation at multiple epochs. We achieve a distance measure at redshift z= 0.275, of r_s(z_d)/D_V(0.275) = 0.1390 ± 0.0037 (2.7 per cent accuracy), where r_s(z_d) is the comoving sound horizon at the baryon-drag epoch, D_V(z) ≡[(1 +z)²D²_Acz/H(z)]^1/3, D_A(z) is the angular diameter distance and H(z) is the Hubble parameter. We find an …