WMAP nine-year results combined with other measurements give the redshift of photon decoupling as z = 1 091.64 ± 0.47, which implies that the scale factor at the time of photon decoupling would be 1 ⁄ 1092.64. So if the matter that originally emitted the oldest CMBR photons has a present distance of 46 billion light-years, then the distance would have been only about 42 million light-years at the time of decoupling.