SIMBAD references

We propose a simple and efficient approach to extract the veiling from low resolution spectra (few hundreds) of T Tauri stars. The method is based on a point to point energy balance, over large scale and deep spectral structures, between the T Tauri spectrum and a template spectrum. We validate the new algorithm, with derivations of the veiling in quasi-simultaneous high resolution (≃10000) and low resolution spectra (≃300) of the Classical T Tauri star BP Tau. For this half veiled object the results coincides within 10%. The low resolution approach is a powerful tool which makes it possible to study variability problems in T Tauri stars, related to e.g. flare or accretion activity, in timescales as short as minutes.