An insight into the progenitors of gamma ray bursts from the optical afterglow observations

We have probed more than 50 gamma ray bursts (GRBs) fields since January 1999 and obtained successful optical afterglow observations for 27 of them. Upper limits were reported for the rest of the cases. Optical observations of GRB afterglows provide information about GRB distances, nature of emission, surroundings, their environments and progenitors. The presence of supernova signature in long-duration GRB afterglows has further strengthened the fact that the collapse of a massive star gives rise to a long-duration GRBs. However, the observed properties of short-duration GRBs are in agreement with the NS-NS or NS-BH coalescence model