Left: Zoomed-in image of continuum core #2 (top right) and #3 (bottom left) overlaid on the 1.3 mm continuum map of G353.41 (in grayscale). The green ellipses represent 1 time the FWHM of the continuum core. Right: Example of the On (black ellipse) and Off (red annulus) spectra computation for each core, used to estimate the core-averaged background-subtracted spectra. Core #3 (top) is the simplest case where no other core overlaps with its annulus (computed between 2.5 and 3.5 times the FWHM of the continuum core). Core #2 (bottom) has another core overlapping its annulus. The overlapping pixels are subtracted from the background estimation.