The black hole X-ray binary (BHXB) GX 339-4 continues to fade in the optical, and has now reached its faintest optical flux since (at least) the start of its 2006-7 outburst (ATels #968, #1027). In this outburst, the source reached peak magnitude values of V ~ 15 and I ~ 14. On the decline of the outburst the source twice re-brightened for several

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The motivation, techniques and performance of the ground-based photometric follow-up of transit detections by the CoRoT space mission are presented. Its principal raison d'être arises from the much higher spatial resolution of common ground-based telescopes in comparison to CoRoT's cameras. This allows the identification of many transit candidates

The known β Cephei star HD 180 642 was observed by the CoRoT satellite in 2007. From the very high-precision light curve, its pulsation frequency spectrum could be derived for the first time (Degroote and collaborators). In this paper, we obtain additional constraints for forthcoming asteroseismic modeling of the target. Our results are based on

Gamma-ray bursts (GRBs) are produced by rare types of massive stellar explosion. Their rapidly fading afterglows are often bright enough at optical wavelengths that they are detectable at cosmological distances. Hitherto, the highest known redshift for a GRB was z = 6.7 (ref. 1), for GRB080913, and for a galaxy was z = 6.96 (ref. 2). Here we report

In this paper, we study the nuclear obscuration of galaxies hosting low ionization narrow emission regions (LINERs) based on their X-ray and optical emission. They show column densities at soft energies (0.5-2 keV) mostly related to the diffuse emission around the active galactic nucleus (AGN), showing a correlation with the optical extinction