Gamma Ray Bursts and Blazars

This talk is divided into two parts, the first part is on Gamma Ray Bursts  and the second one on Blazars, two of the most relativistic sources known so far.
In the first part, I present an investigation on the variability of GRB lightcurves. GRB prompt emission is typically seen in gamma-ray energies, but in rare cases, low energy optical emission is observed along with. According to one of the explanations, the gamma-ray component originates from the compton up-scattered optical synchrotron photons. We examine how different the light curve variability be for the two components, and apply our results in case of GRB080319B. 
Blazars, a subclass of Active Galactic Nuclei, shine all over the electromagnetic spectrum, and display extreme variability as well. In order to understand the physical nature of these sources, it is necessary to construct a multi-band spectral energy distribution (SED). I will 
present preliminary results of high energy (gamma-ray and x-ray) SEDs of a handful of blazars selected from the Fermi 1st year catalog.