Examples of recovered spectra after adding artificial nebulae into the datacube prior to the empirical PSF subtraction. The surface brightness of the artificial nebulae was scaled with integer values of n_spatial according to Eq. (4). After empirical PSF subtraction the spectrum was extracted from the residual datacube using the r_C = 1.25′′ aperture (i.e. the same as in Fig. 2). The spectra are shown in units of 10^-17 erg s^-1 cm^-2 Å^-1. We note that artificial nebulae with n_spat ≥ 5 can be unambiguously discriminated from the background for all objects.