Calibrated results of the Galactic H I 21 cm lines using the two approaches described in Sects. 3.1 and 3.2. These FAST observations targeted IRAS 02524+2046 at Galactic coordinates (l, b) = (158.0°, −33.3°), with a total integration time of 110 minutes. The upper panels demonstrate that the quick calibration method using injected reference signals achieves polarization measurement accuracy of ∼0.2%. The σ_T lines are derived by considering the contributions from H I emission features following the method of Jing et al. (2023). The lower panels show results after a full Mueller matrix solution and leakage correction, reaching a higher calibration accuracy of ∼0.03%.