  We consider radiation emitted by the jitter mechanism in a Blandford-McKee
self-similar blastwave. We assume the magnetic field configuration throughout
the whole blastwave meets the condition for the emission of jitter radiation
and we compute the ensuing images, light curves and spectra. The calculations
are performed for both a uniform and a wind environment. We compare our jitter
results to synchrotron results. We show that jitter radiation produces slightly
different spectra than synchrotron, in particular between the self-absorption
and the peak frequency, where the jitter spectrum is flat, while the
synchrotron spectrum grows as \nu^{1/3}. The spectral difference is reflected
in the early decay slope of the light curves. We conclude that jitter and
synchrotron afterglows can be distinguished from each other with good quality
observations. However, it is unlikely that the difference can explain the
peculiar behavior of several recent observations, such as flat X-ray slopes and
uncorrelated optical and X-ray behavior.

Astrophysics