10 pages, 5 figures, Accepted for publication in Astronomy & AstrophysicsInternational audienceIn this paper we report on the analysis of all the available optical and very high-energy $\gamma$-ray ($>$200 GeV) data for the BL Lac object PKS 2155$-$304, collected simultaneously with the ATOM and H.E.S.S. telescopes from 2007 until 2009. This study also includes X-ray (RXTE, Swift) and high-energy $\gamma$-ray (Fermi-LAT) data. During the period analysed, the source was transitioning from its flaring to quiescent optical states,and was characterized by only moderate flux changes at different wavelengths on the timescales of days and months. A flattening of the optical continuum with an increasing optical flux can be noted in the collected da...
In this paper we report on the analysis of all the available optical and very high-energy $\gamma$-r...
In this paper we report on the analysis of all the available optical and very high-energy γ-ray (>20...
Accepted for publication in the Astrophysical JournalWe report on the first simultaneous observation...
10 pages, 5 figures, Accepted for publication in Astronomy & AstrophysicsInternational audienceIn th...
In this paper we report on the analysis of all the available optical and very high-energy $\gamma$-r...
In this paper we report on the analysis of all the available optical and very high-energy γ-ray (>20...
Accepted for publication in the Astrophysical JournalWe report on the first simultaneous observation...
10 pages, 5 figures, Accepted for publication in Astronomy & AstrophysicsInternational audienceIn th...
In this paper we report on the analysis of all the available optical and very high-energy $\gamma$-r...
In this paper we report on the analysis of all the available optical and very high-energy γ-ray (>20...
Accepted for publication in the Astrophysical JournalWe report on the first simultaneous observation...