The spatial configuration control for the mobile digital direction finder system

2021 ◽  
Author(s):  
V.V. Khutortsev
Keyword(s):  
Radio Emission ◽  
Spatial Configuration ◽  
Optimization Problems ◽  
Measuring System ◽  
Radio Sources ◽  
Electromagnetic Environment ◽  
Promising Direction ◽  
Active Experiments ◽  
Direction Finder ◽  
Configuration Control

A promising direction related to determining the location of radio sources is the use of mobile digital direction finders. Their use is most effective when such direction finders form a system of information-related meters localized in a mobile coordinate system and able to move in it. Depending on the variation of the electromagnetic environment (the termination of radiation by some sources, the appearance of other sources of radio emission, their movement, etc.), the positions of the separated digital direction finders inside such a system should change. To ensure the effective functioning of the measuring system, the paper considers the problem of synthesizing control of the spatial configuration of digital direction finders, the solution of which provides maximum accuracy in determining the coordinates of the location of radio sources. It is shown that the specified problem belongs to the class of active experiments optimization problems or problems of trajectory control of observations.

The GLEAM 4-Jy Sample: The brightest radio-sources in the southern sky

2019 ◽  
Vol 15 (S356) ◽  
pp. 375-375
Author(s):  
Sarah White
Keyword(s):  
Radio Emission ◽  
Active Galactic Nuclei ◽  
Visual Inspection ◽  
Low Frequency ◽  
Galactic Nuclei ◽  
Radio Sources ◽  
Relativistic Jets ◽  
The Galaxy ◽  
Murchison Widefield Array ◽  
Past Activity

AbstractLow-frequency radio emission allows powerful active galactic nuclei (AGN) to be selected in a way that is unaffected by dust obscuration and orientation of the jet axis. It also reveals past activity (e.g. radio lobes) that may not be evident at higher frequencies. Currently, there are too few “radio-loud” galaxies for robust studies in terms of redshift-evolution and/or environment. Hence our use of new observations from the Murchison Widefield Array (the SKA-Low precursor), over the southern sky, to construct the GLEAM 4-Jy Sample (1,860 sources at S151MHz > 4 Jy). This sample is dominated by AGN and is 10 times larger than the heavily relied-upon 3CRR sample (173 sources at S178MHz > 10 Jy) of the northern hemisphere. In order to understand how AGN influence their surroundings and the way galaxies evolve, we first need to correctly identify the galaxy hosting the radio emission. This has now been completed for the GLEAM 4-Jy Sample – through repeated visual inspection and extensive checks against the literature – forming a valuable, legacy dataset for investigating relativistic jets and their interplay with the environment.

ASSESSMENT OF THE ELECTROMAGNETIC ENVIRONMENT AND RADIO MONITORING OF SIGNAL PROPAGATION AND RECEPTION CONDITIONS

2020 ◽  
Author(s):  
С.В. КИЗИМА ◽  
Е.Г. РУДЕНКОВА
Keyword(s):  
Frequency Spectrum ◽  
Electromagnetic Compatibility ◽  
Measurement Data ◽  
Signal Propagation ◽  
Radio Sources ◽  
Electromagnetic Environment ◽  
Radio Monitoring ◽  
Radio Frequency Spectrum ◽  
Radio Signals ◽  
Problematic Situations

Рассматривается технология комплексного радиомониторинга излучений в заданной географической точке. Полученные результаты сопоставляются с разрешенными уровнями излучений. Технология направлена на решение задач оценки условий распространения и приема радиосигналов, планирования использования радиочастотного спектра (РЧС), выявления помех и других проблемных ситуаций, связанных с обеспечением электромагнитной совместимости ( ЭМС) действующих и перспективных радиосредств. The article describes the technology of complex radio monitoring of emissions from multiple radio sources. The measurement data are compared with the permitted emission levels. The application of the technology helps to assess the conditions for the propagation and reception of radio signals, planning the use of the radio frequency spectrum, identifying interference and other problematic situations related to electromagnetic compatibility of existing and promising radio facilities.

scholarly journals 12. The measurement of the distance of the radio sources

1957 ◽  
Vol 4 ◽  
pp. 71-79 ◽  
Author(s):  
R. D. Davies ◽  
D. R. W. Williams
Keyword(s):  
Radio Emission ◽  
Surface Area ◽  
Radio Astronomy ◽  
Angular Size ◽  
Radio Sources ◽  
Absolute Luminosity

In radio astronomy it is becoming increasingly important to know the distance of the radio sources. An identification with astronomical objects observed optically is then more readily obtained and this in turn may allow further investigation of the mechanism of radio emission. A measurement of the distance of sources will also resolve the problem of their distribution in space, showing which are galactic and which are extra-galactic. Furthermore the surface area and absolute luminosity can be estimated from a knowledge of the distance and angular size of a source.

scholarly journals A Novel Method for Estimating the Ambient Medium Density Around Distant Radio Sources from Their Observed Radio Spectra

2021 ◽  
Vol 922 (2) ◽  
pp. 197
Author(s):  
Anna Wójtowicz ◽  
Łukasz Stawarz ◽  
Jerzy Machalski ◽  
Luisa Ostorero
Keyword(s):  
Radio Emission ◽  
Ambient Medium ◽  
Radio Galaxies ◽  
Radiative Properties ◽  
Radio Continuum ◽  
Physical Parameters ◽  
Radio Sources ◽  
Data Set ◽  
Radio Structure ◽  
5 Ghz

Abstract The dynamical evolution and radiative properties of luminous radio galaxies and quasars of the FR II type, are well understood. As a result, through the use of detailed modeling of the observed radio emission of such sources, one can estimate various physical parameters of the systems, including the density of the ambient medium into which the radio structure evolves. This, however, requires rather comprehensive observational information, i.e., sampling the broadband radio continua of the targets at several frequencies, and imaging their radio structures with high resolution. Such observations are, on the other hand, not always available, especially for high-redshift objects. Here, we analyze the best-fit values of the source physical parameters, derived from extensive modeling of the largest currently available sample of FR II radio sources, for which good-quality multiwavelength radio flux measurements could be collected. In the analyzed data set, we notice a significant and nonobvious correlation between the spectral index of the nonthermal radio emission continuum, and density of the ambient medium. We derive the corresponding correlation parameters, and quantify the intrinsic scatter by means of Bayesian analysis. We propose that the discovered correlation could be used as a cosmological tool to estimate the density of ambient medium for large samples of distant radio galaxies. Our method does not require any detailed modeling of individual sources, and relies on limited observational information, namely, the slope of the radio continuum between the rest-frame frequencies 0.4 and 5 GHz, possibly combined with the total linear size of the radio structure.

scholarly journals Some Observations of Shell-type Galactic Radio Sources

1967 ◽  
Vol 20 (3) ◽  
pp. 297 ◽  
Author(s):  
ER Hill
Keyword(s):  
Radio Emission ◽  
Spherical Symmetry ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Milky Way ◽  
Radio Sources ◽  
Radio Observations ◽  
Shell Type ◽  
Rosette Nebula ◽  
Galactic Radio

Radio evidence for two new supernova remnants in the Southern Milky Way is presented. Some new observations of the known supernova remnant, source 1439-62, and of the Rosette nebula, a shell source but not a supernova remnant, are also presented. The problem of finding model shells to fit the radio observations is considered and it is shown that the radio emission from 1439-62 is unlikely to originate in a shell with spherical symmetry.

scholarly journals Magnetic Field Configuration in 4C 39.25

1998 ◽  
Vol 164 ◽  
pp. 115-116 ◽  
Author(s):  
A. Alberdi ◽  
L. Lara ◽  
J.L. Gómez ◽  
J.M. Marcaide ◽  
M.A. Pérez-Torres ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Radio Emission ◽  
Field Configuration ◽  
Radio Sources ◽  
Magnetic Field Configuration ◽  
Relativistic Jet ◽  
Scale Structures ◽  
The Magnetic Field

AbstractWe have performed simultaneous multi-frequency polarization VLBA observations of the compact radio sources 3C 395 and 4C 39.25 which show both stationary and superluminal components in their parsec-scale structures. Those of 3C 395 have been reported elsewhere. Here we report on high resolution maps of the total intensity and polarized radio emission of 4C 39.25, trace the magnetic field configuration along the jet, and explore different possibilities for the nature of the components within the framework of the bent shocked relativistic jet model.

scholarly journals Radio jet and lobe of 3C273

1986 ◽  
Vol 119 ◽  
pp. 211-214
Author(s):  
R.J. Davis
Keyword(s):  
Radio Emission ◽  
Opposite Direction ◽  
Dynamic Range ◽  
Bulk Flow ◽  
Radio Sources ◽  
Relativistic Motion ◽  
Ridge Line ◽  
The Core ◽  
Superluminal Motion ◽  
The One

The ‘superluminal’ motion observed in the cores of radio sources such as 3C273 is now accepted as evidence of relativistic motion within a few parsecs of the centre, but it is less clear whether such speeds persist out to kiloparsec scales. The one-sidedness of such sources is often cited as evidence of relativistic Doppler beaming, but could equally be intrinsic. New MERLIN maps of 3C273 at 151 MHz and 408 MHz have been made with dynamic range of 4.103:1 and 104:1 respectively. These show that (i) there is an extended region or lobe to the south of the main jet; (ii) the radio emission of the jet is continuous from the core to beyond the limit of the optical jet; (iii) no counter-component can be found in the opposite direction to the jet. The ridge-line of the jet shows a ‘wiggle’, the wavelength of which decreases by a factor of 6 along its length. This is interpreted as a deceleration of the bulk flow along the jet.

scholarly journals Clusters with extended radio emission at high frequencies

1978 ◽  
Vol 79 ◽  
pp. 157-159
Author(s):  
R. Wielebinski
Keyword(s):  
Radio Emission ◽  
Direct Measurement ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Coma Cluster ◽  
Extended Source ◽  
High Frequencies ◽  
Extended Radio ◽  
Extended Component ◽  
Perseus Cluster

The existence of ‘haloes’ in clusters of galaxies was deduced by Ryle and Windram (1968) for the Perseus cluster and by Willson (1970) for the Coma cluster at 408 MHz by comparing total flux measured by a single dish with the sum of fluxes of radio sources found in the field. A direct measurement of the extended source Coma C was made by Jaffe et al. (1976) at 610 MHz. the failure to detect the halo of Coma at higher frequencies is attributed by all authors to a steep spectrum of this extended component.

scholarly journals The Intergalactic Medium

1982 ◽  
Vol 97 ◽  
pp. 453-459
Author(s):  
A. C. Fabian ◽  
A. K. Kembhavi
Keyword(s):  
Radio Emission ◽  
Intergalactic Medium ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Intergalactic Gas ◽  
X Ray ◽  
Extended Radio ◽  
X Ray Background ◽  
Ngc 1275 ◽  
Intracluster Gas

The density of intergalactic gas may be an important parameter in the formation of extended radio sources. It may range from ∼ 0.1 particle cm−3 in the centres of some rich clusters of galaxies down to 10−8cm−3 or less in intercluster space. The possible influence of the intracluster gas surrounding NGC 1275 on its radio emission is discussed, and the possibility that a significant fraction of the X-ray background is due to a hot intergalactic medium is explored in some detail.

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