Left: Swift/XRT spectra from band A (red) and band C (blue) fitted using the bmc model. Right: two representative Chandra spectra for different states of M101 ULX-1. Data taken for 2004 July 5 (red), correspond to the high/soft state spectrum and for 2004 January−May and November (blue), correspond to the low/hard state spectrum. Spectra are fitted by a phabs*bmc model with kT_bb = 70 eV (red solid line), for the high state and with kT_bb = 45 eV (blue solid line), for the low state. See also the best-fit parameters listed in Tables 3 and 4 for Swift and Chandra data, respectively.