A method for measuring temperature and molecular number density (N/V) of a gaseous compound as function of distance (d) from a location, the gaseous compound absorbing at least some light, the method comprising - selecting a first wavelength band (Λ 1), a second wavelength band (Λ 2), and a third wavelength (Λ 3) band using information on the spectrum of the absorption coefficient (α) of the gaseous compound and the temperature dependence thereof (α), - generating, for the first wavelength band (Λ 1), the second wavelength band (Λ 2), and the third wavelength band (Λ 3), a pulse sequence comprising a supercontinuum light pulse having a band width from 60 nm to 5000 nm and comprising light having continuously multiple wavelengths in the first wavelength band (Λ 1), the second wavelength band (Λ 2), and the third wavelength band (Λ 3), wherein - the pulse sequence is generated using a light pulse source arrangement comprising a supercontinuum laser source, the method further comprising - guiding the pulse sequence, from a location, in a first direction (D 1), into a thermal device, wherein the thermal device surrounds some gaseous mixture, the gaseous mixture comprising the gaseous compound and scattering particles, whereby ∘ molecules of the gaseous compound absorb at least part of the supercontinuum light pulse, and ∘ particles of the gaseous mixture scatter at least part of the supercontinuum light pulse at various moments of time to scattered light; the method further comprising - measuring, as function of time, the intensity (I, I 0) of the scattered light at the first wavelength band (Λ 1), the second wavelength band (Λ 2), and the third wavelength band (Λ 3), - determining a first piece of information indicative of the differential absorption between the first and the second wavelength bands (Λ 1, Λ 2), using the intensity (I, I 0) of the scattered light at the first wavelength band (Λ 1) and the intensity (I, I 0) of the scattered light at the second wavelength band (Λ 2), - determining a second piece of information indicative of the differential absorption between another pair ([(Λ 1, Λ 8], [(Λ 2, Λ 3]) of wavelength bands selected from the three wavelength bands (Λ 1, Λ 2, Λ 3) using the measured intensities, and - determining, as function of the distance (d) from the location, in the first direction (D 1), using the two pieces of information indicative of the two values of differential absorption, the temperature and the molecular number density (N/V) of the gaseous compound. - selecting a first wavelength band (Λ 1), a second wavelength band (Λ 2), and a third wavelength (Λ 3) band using information on the spectrum of the absorption coefficient (α) of the gaseous compound and the temperature dependence thereof (α), - generating, for the first wavelength band (Λ 1), the second wavelength band (Λ 2), and the third wavelength band (Λ 3), a pulse sequence comprising a supercontinuum light pulse having a band width from 60 nm to 5000 nm and comprising light having continuously multiple wavelengths in the first wavelength band (Λ 1), the second wavelength band (Λ 2), and the third wavelength band (Λ 3), wherein - the pulse sequence is generated using a light pulse source arrangement comprising a supercontinuum laser source, the method further comprising - guiding the pulse sequence, from a location, in a first direction (D 1), into a thermal device, wherein the thermal device surrounds some gaseous mixture, the gaseous mixture comprising the gaseous compound and scattering particles, whereby ∘ molecules of the gaseous compound absorb at least part of the supercontinuum light pulse, and ∘ particles of the gaseous mixture scatter at least part of the supercontinuum light pulse at various moments of time to scattered light; the method further comprising ∘ molecules of the gaseous compound absorb at least part of the supercontinuum light pulse, and ∘ particles of the gaseous mixture scatter at least part of the supercontinuum light pulse at various moments of time to scattered light; the method further comprising - measuring, as function of time, the intensity (I, I 0) of the scattered light at the first wavelength band (Λ 1), the second wavelength band (Λ 2), and the third wavelength band (Λ 3), - determining a first piece of information indicative of the differential absorption between the first and the second wavelength bands (Λ 1, Λ 2), using the intensity (I, I 0) of the scattered light at the first wavelength band (Λ 1) and the intensity (I, I 0) of the scattered light at the second wavelength band (Λ 2), - determining a second piece of information indicative of the differential absorption between another pair ([(Λ 1, Λ 8], [(Λ 2, Λ 3]) of wavelength bands selected from the three wavelength bands (Λ 1, Λ 2, Λ 3) using the measured intensities, and - determining, as function of the distance (d) from the location, in the first direction (D 1), using the two pieces of information indicative of the two values of differential absorption, the temperature and the molecular number density (N/V) of the gaseous compound.