2011ApJ...728...42R

We present the results of an analysis of the prompt gamma-ray emission from GRB 090618 using the RT-2 Experiment on board the Coronas-Photon satellite. GRB 090618 shows multiple peaks, and a detailed study of the temporal structure as a function of energy is carried out. As the gamma-ray burst (GRB) was incident at an angle of 77° to the detector axis, we have generated appropriate response functions of the detectors to derive the spectrum of this GRB. We have augmented these results using the publicly available data from the Swift Burst Alert Telescope detector and show that a combined spectral analysis can measure the spectral parameters quite accurately. We also attempt a spectral and timing analysis of individual peaks and find evidence for a systematic change in the pulse emission characteristics for the successive pulses. In particular, we find that the peak energy of the spectrum, E_p, is found to monotonically decrease with time, for the successive pulses of this GRB.