10 The normalization of afterglows

The values of the CB model parameters that were fitted to the broad band data on GRBs with known redshift - and are listed in Table 3 - are narrowly distributed around their reference values, except for the overall normalization which is much smaller than originally anticipated if $\eta=1$. This normalization ``problem'' may point to inaccuracies in the various hypothesis that we have made. One example is the contention that all of the incident energy of the ISM electrons is radiated in the CB. It may well be that the moving CB deflects and scatters the ISM electrons before they radiate a large fraction of their acquired energy, as suggested by the results of the numerical simulations of Achterberg et al. (2001). But abandoning some of our simplifications would be premature. Indeed, in concluding that in the CB model the normalization of the AGs is more than one order of magnitude too large, we have used our reference parameters to compute the expected values. And there is sufficient elasticity in these parameters to obtain a consistent overall picture of all GRB properties, as we proceed to review and discuss.