Fireballs and cannonballs confront GRB 991208

The broad band afterglow of GRB 991208 provides a good case for a three-sided confrontation: the data, the generally-accepted fireball models of GRBs, and the cannonball (CB) model. Follow-up radio measurements for this GRB have been recently reported. These new data challenge the fireball models and disagree with their predictions, based on earlier broad-band observations, but they are in very good agreement with the predictions of the CB model, based on the same earlier data, and involving many fewer parameters.