Main uncertainties associated with the flux of primary electrons injected from a single bursting source. Top left: varying the age at a fixed distance of 500 pc – notice that taking 1 kpc would have suppressed the 3 kyr source for causality reasons. Top right: varying the distance for a fixed age of 5 kyr. Bottom left: varying the spectral index for fixed age of 5 kyr and fixed distance of 500 pc. Bottom right: varying propagation parameters, with the min, med and max setups from Table 1.