Results for the first data set, recorded at 6:19 UT. Error bars indicate the 1σ confidence level. a) Intensity of the 3.95 μm line in arbitrary unit. Missing values correspond to points where the Gaussian fits were not satisfactory. b) Normalised Stokes parameter q. c) Normalised Stokes parameter u. d) Debiased polarisation rate p_c. e) Polarisation angle θ where p_c ≠ 0. 90° corresponds to a vertical polarisation vector; 0° corresponds to an horizontal vector on the Jovian disk (i.e. referring to the slit direction). f) Normalised Stokes parameter v.