The Bologna Survey of Radio Sources at 408 MHz

1977 ◽  
pp. 25-29
Author(s):  
Carla Fanti ◽  
Carlo Lari
Keyword(s):  
Radio Sources

Radio Measurements of Coronal Magnetic Fields

1994 ◽  
Vol 144 ◽  
pp. 21-28 ◽  
Author(s):  
G. B. Gelfreikh
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Active Regions ◽  
High Sensitivity ◽  
Coronal Magnetic Field ◽  
Transverse Magnetic ◽  
Radio Sources ◽  
Radio Waves ◽  
Solar Active Regions

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

The combined Herstmonceux Cambridge Program of optical positions of radio sources

1978 ◽  
Vol 48 ◽  
pp. 155-166 ◽  
Author(s):  
A. N. Argue ◽  
E. D. Clements ◽  
G. M. Harvey ◽  
C. A. Murray
Keyword(s):  
Standard Error ◽  
Unit Weight ◽  
Radio Sources

SummaryAGK3-based optical positions are presented for 38 counterparts of radio sources selected from the catalogue of Elsmore & Ryle. The measurements were made from plates taken with the 13-inch Astrograph, the 26-inch refractor and the 2.5 m (INT) reflector at Herstmonceux, and the 17-inch Schmidt at Cambridge. The standard error for a mean position of unit weight is 0”.11, and the weights range from 3.0 for the brightest sources to 0.5 for the faintest. Comparison with the radio positions shows no significant differences. The effects of applying the Brorfelde corrections to AGK3 are discussed.

Spatial filtering of signals with spectrum overlapping

2019 ◽  
pp. 27-33
Author(s):  
M. E. Shevchenko ◽  
A. V. Gorovoy ◽  
S. N. Solovyov
Keyword(s):  
Antenna Arrays ◽  
A Priori ◽  
Spatial Filtering ◽  
Spatial Filter ◽  
Radio Sources ◽  
Probability Of Error ◽  
Shift Keying ◽  
A Priori Uncertainty

The paper considers the spatial filtering methods of signals with spectrum overlapping under conditions of a priori uncertainty of the directions of arrival from radio sources. The estimates of the directions of signals arrival obtained by ESPRIT or MUSIC are used in order to build a spatial filter. It is shown that when using ESPRIT, unlike MUSIC, an additional calculations of filter coefficients based on estimates of the directions of signals arrival are not required, and the quadrature components of the signals are formed simultaneously with estimates of the direction of their arrival. The probability of error performances of minimum shift keying signals which were divided by spatial filtering on the basis of ESPRIT and MUSIC using seven-element circular and angular antenna arrays are given.

ROSATX‐Ray Observations of Abell Clusters with Wide‐Angle Tailed Radio Sources

1997 ◽  
Vol 474 (2) ◽  
pp. 580-597 ◽  
Author(s):  
P. L. Gomez ◽  
J. Pinkney ◽  
J. O. Burns ◽  
Q. Wang ◽  
F. N. Owen ◽  
...  
Keyword(s):  
Radio Sources ◽  
Wide Angle ◽  
Abell Clusters

The Gaseous Environments of Powerful Extended Radio Sources

1997 ◽  
Vol 480 (1) ◽  
pp. 96-114 ◽  
Author(s):  
Greg F. Wellman ◽  
Ruth A. Daly ◽  
Lin Wan
Keyword(s):  
Radio Sources ◽  
Extended Radio

CTD 93 and the Nature of Gigahertz Peaked Spectrum Radio Sources

1999 ◽  
Vol 515 (2) ◽  
pp. 558-566 ◽  
Author(s):  
David B. Shaffer ◽  
K. I. Kellermann ◽  
T. J. Cornwell
Keyword(s):  
Radio Sources ◽  
Spectrum Radio

The Heights of Solar Radio Sources at 1424 MHz and 696 MHz

1969 ◽  
Vol 1 (5) ◽  
pp. 192-194 ◽  
Author(s):  
D. G. Cole ◽  
R. F. Mullaly
Keyword(s):  
Solar Activity ◽  
High Resolution ◽  
Solar Disk ◽  
Previous Investigation ◽  
Solar Radio ◽  
Radio Sources ◽  
Grating Interferometer ◽  
Maximum Solar Activity

The heights of solar radio sources at 1424 MHz and 696 MHz have been measured during the years 1965 and 1966. Solar activity at this time was near minimum. The number of radio sources appearing on the solar disk rarely exceeded three at any time and it thus was possible to resolve the majority of these with a high resolution grating interferometer. Many of the previous height measurements at these frequencies have been made near times of maximum solar activity and the confusion of sources within the beam has limited their accuracy. The number of sources studied here is quite considerably higher than in any previous investigation at these frequencies, and the period of observation has been continuous.

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