scholarly journals 5 GHz Continuum Radiation from Southern Hemisphere Galactic HII Regions

1968 ◽  
Vol 21 (6) ◽  
pp. 881 ◽  
Author(s):  
FF Gardner ◽  
M Morimoto
Keyword(s):  
Southern Hemisphere ◽  
Hii Regions ◽  
Radio Sources ◽  
Positional Accuracy ◽  
Continuum Radiation ◽  
Thermal Radio ◽  
5 Ghz ◽  
Better Than ◽  
The Continuum

The continuum radiation from about 36 southern thermal radio sources has been surveyed at 6 cm wavelength with a beamwidth of 4'�2 arc, and maps are shown for 28 of these. The positional accuracy is better than l' arc.

scholarly journals Radio Observations of Hii Regions in M33

1974 ◽  
Vol 60 ◽  
pp. 227-228
Author(s):  
F. P. Israel ◽  
P. C. van der Kruit
Keyword(s):  
Radio Telescope ◽  
Hii Regions ◽  
Radio Sources ◽  
Orion Nebula ◽  
Radio Observations ◽  
Continuum Radiation ◽  
The Continuum

The Westerbork Synthesis Radio Telescope was used to map the continuum radiation of M33 at 1415 MHz. Of 67 radio sources with fluxes S> 1.8 mJy (3σ), 60% coincide with Hα sources. These are all intrinsically stronger than 4 × the Orion nebula, i.e., they are giant Hiiregions. The two strongest sources, NGC 604 (58 mJy) and NGC 595 (20 mJy), are similar to W51.

scholarly journals CPC2 Reduction with Hipparcos and Proper Motions in The Southern Hemisphere

1998 ◽  
Vol 11 (1) ◽  
pp. 551-551
Author(s):  
N. Zacharias ◽  
M.I. Zacharias ◽  
C. de Vegt ◽  
C.A. Murray
Keyword(s):  
Southern Hemisphere ◽  
Systematic Errors ◽  
Reference Star ◽  
Proper Motions ◽  
Positional Accuracy ◽  
Star Catalog ◽  
Naval Observatory ◽  
Celestial Reference System ◽  
First Time ◽  
Better Than

The Second Cape Photographic Catalog (CPC2) contains 276,131 stars covering the entire Southern Hemisphere in a 4-fold overlap pattern. Its mean epoch is 1968, which makes it a key catalog for proper motions. A new reduction of the 5687 plates using on average 40 Hipparcos stars per plate has resulted in a vastly improved catalog with a positional accuracy of about 40 mas (median value) per coordinate, which comes very close to the measuring precision. In particular, for the first time systematic errors depending on magnitude and color can be solved unambiguously and have been removed from the catalog. In combination with the Tycho Catalogue (mean epoch 1991.25) and the upcoming U.S. Naval Observatory CCD Astrograph Catalog (UCAC) project proper motions better than 2 mas/yr can be obtained. This will lead to a vastly improved reference star catalog in the Southern Hemisphere for the final Astrographic Catalogue (AC) reductions, which will then provide propermotions for millions of stars when combined with new epoch data. These data then will allow an uncompromised reduction of the southern Schmidt surveys on the International Celestial Reference System (ICRS).

scholarly journals Populations of Hydrogen-like Atoms or Ions and Radio Recombination Lines (RRL's) Interpretation

2002 ◽  
Vol 199 ◽  
pp. 351-352
Author(s):  
N.I. Rovenskaya
Keyword(s):  
Thermal Radiation ◽  
Electron Density ◽  
Hii Regions ◽  
Kinetic Temperature ◽  
Line Radiation ◽  
Continuum Radiation ◽  
Radio Recombination Lines ◽  
The Continuum

The problem of non-LTE populations has been considered in terms of the departure coefficients ∂bn/∂n as functions of the kinetic temperature Te, the electron density Ne, the continuum radiation flow Ic and the ratios of IHnα, IHnβ, IHnδ and IHnε (the line radiation flows). The ratio of IHnα/IHnβ are sensitive to the thermal radiation from HII regions. Characterized by the relation of ∂2bn/∂n2 > 0, the populations are shown to be inhabited radiatively.

scholarly journals A Radio Survey of the Southern Milky Way at a Frequency of 1440 Mc/s. I. The Isophotes and the Discrete Sources

1962 ◽  
Vol 15 (3) ◽  
pp. 354 ◽  
Author(s):  
DS Mathewson ◽  
JR Healey ◽  
JM Rome
Keyword(s):  
Milky Way ◽  
Galactic Disk ◽  
Spectral Characteristics ◽  
Radio Sources ◽  
Spectral Indices ◽  
Thermal Radio ◽  
Background Emission ◽  
Optical Identifications ◽  
Half Power ◽  
The Continuum

The 1440 Mc/s isophotes of the Southern Milky Way are presented which were obtained with an aerial beam 50' of arc at half-power points. The positions and intensities of the discrete sources resolved from the background emission are listed together with their spectral characteristics determined by comparison with the 85 -5 Mc/s Mills-Cross survey. Of 74 sources, 54 are found to have spectral indices consistent with the assumption that they radiate thermally_ Twelve new identifications of these thermal radio sources haye been made with emission nebulae by comparison with the Stromlo Atlas of Hex emission. The remaining twenty sources have nonthermal spectral indices and no new optical identifications have been made_ The continuum background emission from the galactic disk is discussed in a second paper.

scholarly journals Radio Maps of the Regions RCW 57 and W 49

1989 ◽  
Vol 120 ◽  
pp. 131-131
Author(s):  
N.S. Sabalisck ◽  
Z. Abrahan ◽  
C.E. Tateyama
Keyword(s):  
Spectral Index ◽  
Supernova Remnant ◽  
Angular Resolution ◽  
Radio Sources ◽  
Thermal Radio ◽  
5 Ghz

We present maps of the regions RCW57 and W59 in the frequency of 22 GHz with 4.’6 angular resolution. The thermal radio sources RCW57 II are well resolved in the map. RCW57 I presents, at this frequency a diameter twice as large as that reported at 5 GHz, obtained with similar resolution, but coincides with the size of the source at the wavelenght of 1 mm. In the map of the RCW57 region we detected also the supernova remnant G291.0-0.1, of plerionic type. We find a break in the spectrum of this source between 8 and 22 GHz, with the spectral index changing from −0.29 to −0.77. This behaviour is also found in other remnats of the same type.

scholarly journals A Southern Hemisphere Survey of the Galactic Plane at 5 GHz

1978 ◽  
Vol 31 (4) ◽  
pp. 351
Author(s):  
RF Haynes ◽  
JL Caswell ◽  
LWJ Simons
Keyword(s):  
Detection Limit ◽  
Southern Hemisphere ◽  
Galactic Plane ◽  
Point Sources ◽  
Half Power ◽  
5 Ghz ◽  
Better Than

Seventy five maps are presented showing the 5 GHz emission from the galactic plane in the range I = 190� ~ 360� .... 40� for - 2� < b < 2� (an area of approximately 600 square egrees). The method of observing and the computer reduction of the data are discussed. the telescope resolution is 4'�1 arc to half-power points and the detection limit for point sources is better than 0�5 Jy.

scholarly journals 5-GHz VLBI Imaging Observations of 7 Equatorial AGNs

2002 ◽  
Vol 184 ◽  
pp. 304-305
Author(s):  
Z.-Q. Shen ◽  
D. R. Jiang ◽  
Y.J. Chen ◽  
T.-S. Wan
Keyword(s):  
Radio Sources ◽  
Preliminary Results ◽  
The Third ◽  
5 Ghz

AbstractSince 1992 we have been conducting a 5-GHz VLBI imaging survey of southern and equatorial radio sources. So far, we have published the results of two observing sessions with 26 southern radio sources imaged in total (Shen et al. 1997; 1998). In this paper, we present the preliminary results of the third session of observations of 7 equatorial sources in the sample.

scholarly journals The follow-up European VLBI Network observations of twelve GPS radio sources at 5 GHz

2010 ◽  
Vol 518 ◽  
pp. A23 ◽  
Author(s):  
L. Cui ◽  
X. Liu ◽  
J. Liu ◽  
H.-G. Song ◽  
Z. Ding
Keyword(s):  
Radio Sources ◽  
5 Ghz

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.

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