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High Energy Astrophysics Group focuses on the research of cosmic objects in X-ray and gamma spectra region, mainly gamma-ray bursts, active galaxies-blazars, and high energy sources located in our Galaxy. Participation in the satellite experiments (mainly with the collaboration of European Space Agency ESA), operation and another development/innovation of the supporting ground-based experiments, mainly CCD telescopes and robotic telescopes. Confirmation and specification of physical models of the sources, study of the related physical processes.

High energy astrophysics is a progressive and rapidly developing field with high priority in the international research, with a close relation to the cosmic experiment and to the physics as a whole. The objects which emit high energy radiation have the Galactic and extragalactic origin. The Galactic ones are mainly X-ray binaries, pulsars, X-ray novae, X-ray transients, cataclysmic variables, stars with coronal emission. The extragalactic ones represent mainly active galactic nuclei (AGN), blazars, supernovae, gamma-ray bursts. Various correlations are being studied and identified (e.g. between gamma-ray bursts and supernovae). One of the current tasks is the physics of jets, existing mainly in AGN and blazars, but probably also in other kinds of object (gamma-ray bursts), and the study of the regions of nucleosynthesis. Continuously growing outputs toward general physics and cosmology, study of the Universe in its early stadiums, objects in very large (cosmologic) distances, final phases of the lives of stars etc. The satellite projects represent the substantial basis for the experiments (at present mainly XMM Newton, Chandra AXAF, INTEGRAL ESA), they yield a huge amount of data which are then submitted to scientific analyses and interpretations. Right the satellite data led to a great progress in high energy astrophysics as a whole. A complex analysis is an important method in which the objects are studied simultaneously in various spectral regions. Also suitably organized ground-based observations considerably contribute to the understanding of the physical processes, mainly if they are correlated with the measurements from the satellites. Valuable data are obtained also in the framework of campaigns when a given object is intensively and simultaneously studied from the Earth and by the satellites. Optical monitoring has a growing importance, enabling a rapid observing with a satellite (so called target of opportunity) in case of an outburst or change of activity. The Ondrejov group successfully participated in several wide international satellite and ground-based projects

High Energy Group of the Astronomical Institute is the largest one in this research field in Czech Republic. This group collaborates with universities, mainly with Czech Technical University in Prague and Masaryk University in Brno. It achieved many innovations in the field, for example in the preparation and operation of the robotic ground-based telescopes for the cosmic satellite projects and in its involvement in the development of innovated technologies and procedures for the astrophysical satellite projects. Important in the national context is the extensive participation of students, diploma and doctoral students.

In the international context, High Energy Group achieved acknowledgements mainly by its enter to the international collaborations (satellite projects ESA INTEGRAL and ESA XEUS, project BOOTES, research of blazars, gamma-ray bursts, cataclysmic variables and related binary high energy sources). Internationally acknowledged is the participation in the development of new astrophysical instruments for the satellites, mainly the innovated X-ray optics for future great satellite experiments ESA and NASA. This group achieved good results also in the area of the optical observations of the counterparts of the gamma-ray bursts, research of activity of the binary systems with a compact object, and in the studies of optical transients.

Recent and future plans

In the field of high energy astrophysics, we will focus on a complex scientific research of the cosmic sources of high energy radiations by means of both satellite and ground-based experiments with an emphasis on the method of the multispectral analysis and wide international collaboration. The field of the satellite projects will consider mainly a continuation of the project ESA INTEGRAL by analyses of gamma-ray bursts, blazars, and high energy sources in our galaxy (mainly cataclysmic variables and X-ray transients). International Science Working Team of the INTEGRAL project delegated us to lead the analyses of cataclysmic variables in the framework of INTEGRAL Core Programme; we participate also in other subsections (active galactic nuclei (AGN), gamma-ray bursts, X-ray sources in our Galaxy) as the members of the relevant teams. In addition, we are involved in 3 observing proposals in the framework of the programme AO-2 (gamma-ray bursts, blazars, the cataclysmic variable AE Aqr). We lead the analyses of the detected gamma-ray burst GRB030501 in the framework of the Core Programme according to the rotation scheme with other teams according to a time table (the OMC GRB team usually receives one month per year). Our further collaborations consider the great project ESA XEUS and LOBSTER. As for the study of gamma-ray bursts, we assume an involvement in analysis of the observations from the satellites INTEGRAL, HETE a Swift. Strategies and methods: (1) The satellite project ESA INTEGRAL. Analysis of the obtained observations of gamma-ray bursts in the framework of the negotiated international collaboration with utilizing the data from the satellite (mainly the light curves, spectra, spectral evolution) and the ground-based experiments with the emphasis on the physical interpretation of the observed phenomena. Analysis of other high energy sources with this satellite with the focus on blazars and sources in our Galaxy. (2) Research of blazars: multispectral analyses using the data from both the ground-based telescopes and the satellites (INTEGRAL etc.), study of colours, time evolution, outbursts. (3) Research of binary sources of high energy radiation in our Galaxy (cataclysmic variables, X-ray binaries, X-ray transients, supersoft X-ray sources); complex and multispectral analyses (ground-based and satellite data, data from INTEGRAL), observations and observing campaigns, study of the physical processes acting on various time scales including long-term activity of these objects and their outbursts, physical interpretation, development of the physical models. (4) Research of gamma-ray bursts: rapid follow-up optical observations and study of optical afterglows and optical transients using the robotic ground-based telescopes BART and BOOTES, development and start of operation of innovated instruments (SUPER-BART), study of colour indices and their time evolution with the aim to study the diagnostics of the environment and other physical relations. (5) Research of optical transients: analysis of the data from the optical monitors, digitized archival plates and CCD monitors. Complex analyses of the detected phenomena, deep analyses of their positions with the aim to find possible quiescent counterpart, alternatively so called host galaxy. (6) The satellite project ESA XEUS: participation in the scientific goals and the programme, involvement in the optical system of the telescope (development, simulation, modelling, etc.). (7) The project LOBSTER: participation in scientific programme and in the preparation of the experiment.

Responsible Scientist (R_Sci) of CVs INTEGRAL core programme is Dr. René Hudec.

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