Four examples of temperature distribution retrieval from realistic observations of the planet spectrum using the JWST-NIRSPEC instrument. For each case, 20 trials were done (blue curves). The temperature distribution to be retrieved corresponds to the red curve. The label indicates the conditions in terms of S/N (at the longest wavelength) and of wavelength range. In a few cases, one notes that one or two catastrophic solutions are found. For a S/N = 20 and a wavelength range extending to 4.5 μm, the accuracy on the retrieval of the initial distribution is good (<10 K), and no catastrophic solution is found.