D. Light Curve During the Newtonian transition

At t t_NR (see Eq. 81) the afterglow reaches the Newtonian Sedov-Taylor phase. During this phase the adiabatic hydrodynamic is described by Eq. 83. Frail et al. [107] calculate the synchrotron spectrum and light curve of the afterglow in this stage. The energy scaling implies that B t^-3/5 and _e,min t^-6/5. Combined together this yields _m t^-3. Using the standard assumptions of equipartition and of a power law electron's distribution they find :

(97)

This late time light curve provides a simple "calorimetric" estimate of the afterglow energy at this stage (see Section IID). Additionally as the radio flux is rather large and as it varies on a scale of several month it can be used for search of orphan radio afterglows (see Levinson et al. [215] and Section VIIK2).