Multi-band photometry of GRB 110205A + 110213A

The former shows optical emission since the early stages of the prompt phase, followed by the steep rising in flux up to ~1000s after the burst (t^-{alpha}^ with {alpha}=-6.13+/-0.75). We discuss this feature in the context of the reverse-shock scenario and interpret the following single power-law decay as being forward-shock dominated.

Polarization measurements, obtained with the RINGO2 instrument mounted on the Liverpool Telescope, also provide hints on the nature of the emitting ejecta. The latter event, instead, displays a very peculiar optical to near-infrared light curve, with two achromatic peaks. In this case, while the first peak is probably due to the onset of the afterglow, we interpret the second peak to be produced by newly injected material, signifying a late-time activity of the central engine.