Commissioning of the Muon Track Reconstruction in the ATLAS Experiment

The Muon Spectrometer for the ATLAS experiment at the LHC is designed to identify muons with transverse momentum greater than 3 GeV/c and measure muon momenta with high precision up to the highest momenta expected at the LHC. The 50-micron sagitta resolution translates into a transverse momentum resolution of 10% for muon transverse momenta of 1 TeV/c. Design resolution requires an accurate calibration of positions and distortions of the muon detectors as well as accurate calibration of the time to distance relation in the Monitored Drift Tubes. We describe the software chain that implements alignment and calibration corrections as well as the muon reconstruction algorithms. We report on the performance of the complete software chain in the context of ATLAS combined cosmics data taking.