We present results of a multi-site photometric campaign on the high-amplitude δ Scuti star KIC 6382916 in the Kepler field. The star was observed over a 85-d interval at five different sites in North America and Europe during 2011. Kepler photometry and ground-based multicolour light curves of KIC 6382916 are used to investigate the pulsational content and to identify the principal modes. High-dispersion spectroscopy was also obtained in order to derive the stellar parameters and projected rotational velocity. From an analysis of the Kepler time series, three independent frequencies and a few hundred combination frequencies are found. The light curve is dominated by two modes with frequencies f 1 = 4.9107 and f 2 = 6.4314 d −1 . The third mode with f 3 = 8.0350 d −1 has a much lower amplitude. We attempt mode identification by examining the amplitude ratios and phase differences in different wavebands from multicolour photometry and comparing them to calculations for different spherical harmonic degree, l. We find that the theoretical models for f 1 and f 2 are in a best agreement with the observations and lead to value of l = 1 modes, but the mode identification of f 3 is uncertain due to its low amplitude. Non-adiabatic pulsation models show that frequencies below 6 d −1 are stable, which means that the low frequency of f 1 cannot be reproduced. This is further confirmation that current models predict a narrower pulsation frequency range than actually observed.

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We report the detection of a faint optical flash by the 2‐m Faulkes Telescope North simultaneously with the second of two prompt γ‐ray pulses in INTEGRAL gamma‐ray burst (GRB) 080603A, beginning at trest= 37 s after the onset of the GRB. This optical flash appears to be distinct from the subsequent emerging afterglow emission, for which we present comprehensive broad‐band radio to X‐ray light curves to 13 d post‐burst and rigorously test the standard fireball model. The intrinsic extinction towards GRB 080603A is high (AV, z= 0.8 mag), and the well‐sampled X‐ray‐to‐near‐infrared spectral energy distribution is interesting in requiring an LMC2 extinction profile, in contrast to the majority of GRBs. Comparison of the γ‐ray and extinction‐corrected optical flux densities of the flash rules out an inverse‐Compton origin for the prompt γ‐rays; instead, we suggest that the optical flash could originate from the inhomogeneity of the relativistic flow. In this scenario, a large velocity irregularity in the flow produces the prompt γ‐rays, followed by a milder internal shock at a larger radius that would cause the optical flash. Flat γ‐ray spectra, roughly F∝ν−0.1, are observed in many GRBs. If the flat spectrum extends down to the optical band in GRB 080603A, the optical flare could be explained as the low‐energy tail of the γ‐ray emission. If this is indeed the case, it provides an important clue to understanding the nature of the emission process in the prompt phase of GRBs and highlights the importance of deep (R > 20 mag), rapid follow‐up observations capable of detecting faint, prompt optical emission.

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