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tokens: scale them by the corresponding PFs estimated over the same energy ranges. However, also this procedure might not necessarily yield a realistic estimate of the total flux of the pulsar, as it implicitly assumes that no difference exists between the spectral shapes of the pulsed and pulsed plus unpulsed emission (which is not necessarily the case). 3.2 Estimating the spectrum of the total X-ray emission For all those cases where the spin signal is not detected in the X-ray band, or the photon counting statistics is too low to extract a meaningful pulsed spectrum, the closest approximation to the intrinsic pulsar spectrum and flux can only be derived by a spatial analysis of the total emission (pulsed plus unpulsed). This approach leads to estimate an upper limit to the real flux, owing to the possible residual contamination from the background. It is expected to give a very close approximation to the intrinsic pulsar emission especially in the Chandra data, where this contamination can be minimized. 3.3 Similarities and differences in the pulsed and total X-ray SEDs: a few examples In Fig. 1 , we show a comparison for a few X-ray SEDs extracted considering either the total (pulsed plus unpulsed) emission (in black; this work, with procedural details given below) or the pulsed-only emission (in red; from Kuiper Hermsen 2015 ). In most cases, these SEDs overlap in energy only partially, as the pulsed SEDs were typically extracted at higher energies with respect to the pulsed plus unpulsed SEDs that are extracted here over the soft X-ray energy range (below 10 keV). Figure 1. Total (pulsed plus unpulsed) and pulsed-only X-ray SEDs for a sample of pulsars. The former were derived in this work and are shown in black, the latter are taken from Kuiper Hermsen ( 2015 ) and are shown in red. Clearly, the total (pulsed plus unpulsed) spectrum of J0205+6449 and J1513−5908 cannot be reproduced just by scaling the pulsed spectrum for the (average) value of the PF (≳21 per cent and ∼88 per cent), indicating a strong contamination from diffuse emission in the pulsar spectral data, which can hardly be removed (this is clearly more evident for the case of J0205+6449, and it is consistent with the detection of the PWN also at GeV energies (Li et al. 2018a ). On the other hand, the total and pulsed SEDs of J1813−1246, J1846−0258, J2022+3842, and J2229+6114 are consistent with each other once the pulsed SED is rescaled by the value for the corresponding PF, implying a comparatively small contamination from the diffuse and/or background emission. In particular, the pulsed SEDs of J1813−1246, J2022+3842, and J2229+6114 are slightly below the corresponding total SEDs (note that in all these cases the PFs are >75 per cent; see Table 1 ). Although the pulsed SED of J1846−0258 appears considerably below the SED for the total emission, the two SEDs turn out to be consistent with each other once the rather small PF is taken into account (∼31 per cent; see again Table 1 ).