Spectral energy distribution of GX 13+1 in EF_E representation as observed by IXPE. The left, middle, and right panels are for the Stokes parameters I, Q, and U, respectively. The fit is performed in the 2−8 keV energy band using the three IXPE detectors and applying the tbabs*(diskbb*polconst+bbodyrad*polconst) model. The total model is shown with the solid black line, while diskbb and bbodyrad are indicated with the dashed and dotted lines, respectively. The lower subpanels show the residuals between the data and the best fit. In the joint spectral fit, we applied a rebinning to obtain at least 50 counts per bin as in Swift/XRT, while for the spectropolarimetric analysis, a constant grouping was applied to have energy bins of 200 eV.