Real-Time VLBI Observations of Compact Objects
0
Citation
0
Reference
10
Related Paper
Abstract:
Radio emission from Galactic stellar black holes is usually very weak and higly variable on short timescales. To image these systems at high angular resolution using the very long baseline interferometry (VLBI) technique with high fidelity is a challenge. To increase the sensitivity of VLBI observations, the data rates have to be increased considerably. One way to handle multi‐Gbit/s data is to stream these from the telescopes to the central data processor in real‐time, a relatively new technique called e‐VLBI. I will describe e‐VLBI developments in the European VLBI Network (EVN).Keywords:
Very-long-baseline interferometry
High energy gamma-ray astronomy is a newly emerging and very successful branch of astronomy and astrophysics. Exciting results have been obtained by the current generation Cherenkov telescope systems such as H.E.S.S., MAGIC, VERITAS and CANGAROO. The H.E.S.S. survey of the galactic plane has revealed a large number of sources and addresses issues such as the question about the origin of cosmic rays. The detection of very high energy emission from extragalactic sources at large distances has provided insights in the star formation during the history of the universe and in the understanding of active galactic nuclei. The development of the very large Cherenkov telescope array system (CTA) with a sensitivity about an order of magnitude better than current instruments and significantly improved sensitivity is under intense discussion. This observatory will reveal an order of magnitude more sources and due to its higher sensitivity and angular resolution it will be able to detect new classes of objects and phenomena that have not been visible until now. A combination of different telescope types will provide the sensitivity needed in different energy ranges.
Cherenkov Telescope Array
Cite
Citations (6)
Space VLBI enables high angular resolution and high dynamic range imaging through an extension of ground-based VLBI. The TDRSS space VLBI experiments in the 1980s were followed by the first space VLBI imaging mission, VSOP, in the 1990s. The new century holds the promise of the VSOP-2 and ARISE missions, which aim for more sensitive, higher angular resolution and higher observing frequency capabilities. These missions will enable AGNs to be viewed much more clearly and will make broader science areas, including lower brightness sources, accessible. It is noted that in all space VLBI missions, international collaboration in global sense plays an important role.
Very-long-baseline interferometry
Cite
Citations (0)
Very Long Baseline Interferometry (VLBI) technique occupies a special place among tools for studying the Universe due to its record high angular resolution. The latter is in the inverse proportion to the length of interferometer baseline at any given wavelength. Until recently, the available angular resolution in radio domain of about 1 milliarcsecond at centimeter wavelengths was limited by the diameter of the Earth. However, many astrophysical problems require a higher angular resolution. The only way to achieve this at a given wavelength is to create an interferometer with the baseline larger than the Earth's diameter by placing at least one telescope in space. In February 1997, the first dedicated Space VLBI mission, VLBI Space Observatory Program (VSOP), led by the Institute of Space and Astronautical Sciences (Japan) has been launched (Hirabayashi 1997). The VSOP mission opens a new dimension in the development of radio astronomy of extremely high angular resolution and will be followed by other Space VLBI missions. A review of scientific drives and technological challenges of the next generation Space VLBI mission have been discussed, for example, by (1996) and (1997).
Very-long-baseline interferometry
Angular diameter
Cite
Citations (0)
Very-long-baseline interferometry
space science
Spitzer Space Telescope
Cite
Citations (2)
The use of very long baseline interferometry (VLBI) for investigating small angular features in galactic and extragalactic radio sources is discussed. Mathematical models are developed to describe the operation of an interferometer and to show the variations in the resultant fringe frequency. The types of sources to which the interferometer will respond are identified.
Very-long-baseline interferometry
Baseline (sea)
Angular diameter
Cite
Citations (0)
Cite
Citations (0)
Very-long-baseline interferometry
Angular diameter
Cite
Citations (2)
The development of very long baseline radio-interferometry methods (VLBI) allowed us to increase the angular resolution of radio astronomy tools from several degrees to thousandth fractions of arc second, i.e., by more than six orders of magnitude. Such a high angular resolution makes it possible to obtain images of celestial objects with the finest structure, which provides basically novel possibilities in the area of astrophysics and astronomy. This method is a single tool for studying the structure of quasars, radio-galaxies at cosmological distances. In the framework of the Radioastron Project, we developed and tested a fourfrequency highly sensitive receiving complex for the wavelengths: = 92 cm, 18 cm, 6 cm, and 1.35 cm. The complex was designed for the equipment of ground receiving stations participating in VLBI interferometric observations. An RT-22 radio telescope is equipped with this receiving complex at the Pushchino Radio Astronomy Observatory. A VLBI station for four wavelengths was organized on the basis of this instrument. The general flowchart of the receiving complex for VLBI observations on an RT-22 in Pushchino is presented in Fig. 1.
Very-long-baseline interferometry
Radio Astronomy
Astrometry
Cite
Citations (0)
The concept of a next generation Space VLBI (Very Long Baseline Interferometry) mission is considered as a space-based extension of a ground-based VLBI network containing the Square Kilometre Array (SKA). Such a system will improve the sensitivity of VLBI observations by more than one order of magnitude, making it possible to enter the totally unexplored area of milliand submillijansky sources at the sub-milliarcsecond angular scale. As in any radically new parameter area, the most spectacular astrophysical applications of a “SKA plus Space VLBI” system are hardly predictable. However even foreseeable studies offer sufficient justification to pursue Space VLBI as one of the most attractive modes of operations of the Square Kilometre Array. Two SKA configurations, the nominal “compact” configuration with a diameter of 500 km and an extended “global” configuration with size comparable to the Earth’s diameter are considered. The latter configuration has a number of serious advantages important for general VLBI and Space VLBI applications.
Very-long-baseline interferometry
Radio Astronomy
Cite
Citations (1)
Very Long Baseline Interferometry (VLBI) technique occupies a special place among tools for studying the Universe due to its record high angular resolution. The latter is in the inverse proportion to the length of interferometer baseline at any given wavelength. Until recently, the available angular resolution in radio domain of about 1 milliarcsecond at centimeter wavelengths was limited by the diameter of the Earth. However, many astrophysical problems require a higher angular resolution. The only way to achieve this at a given wavelength is to create an interferometer with the baseline larger than the Earth’s diameter by placing at least one telescope in space. In February 1997, the first dedicated Space VLBI mission, VLBI Space Observatory Program (VSOP), led by the Institute of Space and Astronautical Sciences (Japan) has been launched (Hirabayashi 1997). The VSOP mission opens a new dimension in the development of radio astronomy of extremely high angular resolution and will be followed by other Space VLBI missions. A review of scientific drives and technological challenges of the next generation Space VLBI mission have been discussed, for example, by Gurvits et al. (1996) and Ulvestad et al. (1997).
Very-long-baseline interferometry
Radio Astronomy
Angular diameter
Cite
Citations (0)