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Pavlenko E.P.,SRI Crimean Astrophysical Observatory | Samsonov D.A.,SRI Crimean Astrophysical Observatory | Antonyuk O.I.,SRI Crimean Astrophysical Observatory | Andreev M.V.,Russian Academy of Sciences | And 2 more authors.
Astrophysics | Year: 2012

Photometric studies of the dwarf nova V503 Cygni have been conducted for 29 nights at the Crimean Astrophysical Observatory and at the Terskol Observatory during 2010. We detected none of the socalled "negative" superhumps observed previously in the quiet state and in ordinary (short) outbursts [1]. Instead, during the ordinary outbursts and in a superoutburst and for some time after its termination, we recorded "positive" superhumps. At other times outside the outbursts we have for the first time detected oscillations in the brightness at the orbital period of 0. 077760(3) days that have not been observed photometrically before. © 2012 Springer Science+Business Media New York.

Cano Z.,Liverpool John Moores University | Bersier D.,Liverpool John Moores University | Guidorzi C.,Liverpool John Moores University | Guidorzi C.,University of Ferrara | And 80 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2011

We present ground-based and Hubble Space Telescope optical observations of the optical transients (OTs) of long-duration Gamma Ray Bursts (GRBs) 060729 and 090618, both at a redshift of z=0.54. For GRB 060729, bumps are seen in the optical light curves (LCs), and the late-time broad-band spectral energy distributions (SEDs) of the OT resemble those of local Type Ic supernovae (SNe). For GRB 090618, the dense sampling of our optical observations has allowed us to detect well-defined bumps in the optical LCs, as well as a change in colour, that are indicative of light coming from a core-collapse SN. The accompanying SNe for both events are individually compared with SN1998bw, a known GRB supernova, and SN1994I, a typical Type Ic supernova without a known GRB counterpart, and in both cases the brightness and temporal evolution more closely resemble SN1998bw. We also exploit our extensive optical and radio data for GRB 090618, as well as the publicly available Swift-XRT data, and discuss the properties of the afterglow at early times. In the context of a simple jet-like model, the afterglow of GRB 090618 is best explained by the presence of a jet-break at t - t o > 0.5 d. We then compare the rest-frame, peak V-band absolute magnitudes of all of the GRB and X-Ray Flash (XRF)-associated SNe with a large sample of local Type Ibc SNe, concluding that, when host extinction is considered, the peak magnitudes of the GRB/XRF-SNe cannot be distinguished from the peak magnitudes of non-GRB/XRF SNe. © 2011 The Authors. Monthly Notices of the Royal Astronomical Society © 2011 RAS.

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