Spectroscopic light-curve precision, showing wavelength (in μm) on the x-axis, and the median-absolute deviation (MAD, in ppm) on the y-axis. The MAD-values from our data reduction (blue points) are compared to the photon-noise contribution (grey solid line) from a JexoSim simulation. The black solid line shows the corresponding full noise budget, and the grey dashed line represents twice the photon-noise contribution. Individual channels deviating by a factor of 1.75 from the photon-noise contribution (red crosses) are not considered in further analysis.