Abstract:
Early time optical observations of GRBs are very important
for revealing the prompt emission and afterglow properties of these energetic
explosions. The observations of the well-studied GRBs by Swift
indicate that early time properties of the optical light-curves share diverse
set of features broadly consistent with the predictions made by various afterglow
models though outliers exists. The comparison of a subset of wellmonitored
GRBs and their early time properties at optical are compared
with that seen at X-ray (Swift-XRT) and
γ-ray frequencies. In most of the
cases, the very early optical observations of GRBs do not trace the canonical
decay nature seen at XRT frequencies, suggesting different origins for
the observed early emissions in the two bands. In some of the early optical
light-curves, the smooth rise and decay features are consistent with the onset
of the afterglow although such features are also expected if the emission
is seen off-axis and/or the outflow is structured.
