Example of a synthetic Gaussian fit performed with MASSA. In this case, HC₃N (16 − 15) (the line on the left) is blended with H₂CO (2_0,2 − 1_0,1) (the line to the right). The bump at higher frequencies is the emission from the centre of the galaxy picked up by the telescope beam. This bump was originally subtracted before any Gaussian fit, although here we show it as an example of the strength of this emission. See details about the Gaussian fitting in the text.