We have carried out an optical follow-up of twelve ROSAT discovered candidate members of the Coma Berenices open cluster. VRI photometry and low resolution ( ~ 3 Å) spectroscopy in the range 3800-7000 Åwere performed to obtain colour-magnitude diagrams, proper motions, spectral types, chromospheric activity levels and radial velocities that allow

We present the polarization monitoring carried out for two SNe associated with GRBs: XRF060218/SN2006aj and XRF080109/SN2008D. For XRF060218/SN2006aj we measured a mean polarization of P˜4% at 2.6-5.6 days after the X-ray event. This is the highest polarization value ever measured for a supernova. We derived the intrinsic polarization of XRF080109

We searched for X-ray counterparts of optical novae detected in M 31 and M 33. We combined an optical nova catalogue from the WeCAPP survey with optical novae reported in the literature and correlated them with the most recent X-ray catalogues from ROSAT, XMM-Newton, and Chandra, and in addition searched for nova correlations in archival data. We

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We present multicolour photometry of the M8.5V ultracool dwarf `pulsar' TVLM 513-46546 (hereafter TVLM 513) obtained with the triple-beam photometer ULTRACAM. Data were obtained simultaneously in the Sloan-g' and Sloan-i' bands. The previously reported sinusoidal variability, with a period of 2 h, is recovered here. However, the Sloan-g' and Sloan

We present time-resolved spectroscopy and photometry of SDSS J100658.40+233724.4, which we have discovered to be an eclipsing cataclysmic variable with an orbital period of 0.18591324 days (267.71507 min). The observed velocity amplitude of the secondary star is 276 ± 7 km s-1, which an irradiation correction reduces to 258 ± 12 km s-1. Doppler