Upper panel: datasets that compose the spectrum 2 analysis. Black data: XIS023 spectrum; red data: BAT spectrum; green data: ISGRI spectrum; blue data: Suzaku/HXD-PIN spectrum; light blue: XIS0 spectrum. Lower panels: residuals in units of σ for the continuum models of Table 1; upper mid-panels: only continuum, lower mid-panels: continuum with the addition of a cyclotron absorption feature at  ~ 31 keV.