We report the photoemission spectra from a high quality thin film sample of Y1Ba2Cu3C7-δ at room temperature and bulk samples of Y1Ba2Cu3C7-δ at different temperatures. The experimental data are interpreted within the configuration interaction model of Anderson Hamiltonian. The experimental values for Δ, U and T are determined. We also give the reasons why we think PES data reflect the intrinsic property of the superconductors. Furthermore, we emphasize the importance of the presence of a 3d8-like satellite which signals the strong correlation among 3d electrons.