Left panel: SED from VIZIER database (dotted black line) with the fit for the temperature-gradient model (red line), including Spitzer (solid magenta line) and ISO SWS data (blue line) and MATISSE calibrated flux in green. Right panel: zoom in to 3–4 μm, where we represent the C-CH template in low resolution (blue line). Blue and red areas correspond to two different bands: 3.3 μm – aromatic and 3.4 μm – aliphatic.