Swift XRT effective area measured at the Panter end-to-end tests

The Swift X-ray Telescope (XRT) is designed to make astrometric, spectroscopic and photometric observations of the X-ray emission from Gamma-ray bursts and their afterglows, in the energy band 0.2 - 10 keV. Here we report first results of the analysis of Swift XRT effective area at five different energies as measured during the end-to-end calibration campaign at the Panter X-ray beam line facility. The analysis comprises the study of the effective area both on-axis and off-axis for different event grade selection. We compare the laboratory results with the expectations and show that the measured effective area meets the mission scientific requirements.