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تسجيل مستخدم جديدGROND coverage of the main peak of Gamma-Ray Burst 130925A
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Prompt or early optical emission in gamma-ray bursts is notoriously difficult to measure, and observations of the dozen cases show a large variety of properties. Yet, such early emission promises to help us achieve a better understanding of the GRB emission process(es). We performed dedicated observations of the ultra-long duration (T90 about 7000 s) GRB 130925A in the optical/near-infrared with the 7-channel Gamma-Ray Burst Optical and Near-infrared Detector (GROND) at the 2.2m MPG/ESO telescope. We detect an optical/NIR flare with an amplitude of nearly 2 mag which is delayed with respect to the keV--MeV prompt emission by about 300--400 s. The decay time of this flare is shorter than the duration of the flare (500 s) or its delay. While we cannot offer a straightforward explanation, we discuss the implications of the flare properties and suggest ways toward understanding it.
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We have performed a systematic study of Gamma-Ray Bursts (GRBs), which have various values in the peak energy of the ${ u}F_{ u}$ spectrum of the prompt emission, $E_{{rm peak}}$, observed by textsl{Swift}/BAT and textsl{Fermi}/GBM, investigating the
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