NICER (green) and NuSTAR (black and red) combined spectrum of GRO J1750-27. Top panel: data (crosses) and best-fit model (continuous lines). Middle: Ratio residuals (data divided by model) using Model I Smooth (see Table 2) but without the inclusion of a cyclotron line. Bottom: residuals from the best-fit model including a Gaussian absorption line near 43 keV to account for the cyclotron resonant scattering feature. Data were rebinned for plotting purposes.