78. The lunar occultation of a radio star and the derivation of an upper limit for the density of the lunar atmosphere

1957 ◽  
Vol 4 ◽  
pp. 403-405 ◽  
Author(s):  
B. Elsmore
Keyword(s):  
Radio Source ◽  
Large Diameter ◽  
Circular Region ◽  
Radio Brightness ◽  
Interferometric Method ◽  
Filamentary Structure ◽  
Lunar Occultation ◽  
Upper Limit

Observations were made at Cambridge on 26 April 1955 of the lunar occultation of the large-diameter radio source in the constellation of Gemini. This radio source, having r.a. 06h 13m 37s and dec. 22° 38′ (1950·0), has been identified by Baldwin and Dewhirst (1954) [1] as the galactic nebulosity IC443, which consists of a filamentary structure contained within a circular region of 24′·5 radius. Baldwin and Dewhirst also succeeded in measuring the distribution of radio ‘brightness’ across the source using an interferometric method; their measurements indicate that the diameter of the radio source is approximately the same as that of the visible nebulosity.

scholarly journals Radio observations of the lunar atmosphere

1959 ◽  
Vol 9 ◽  
pp. 47-49
Author(s):  
B. Elsmore
Keyword(s):  
Radio Source ◽  
Crab Nebula ◽  
Large Diameter ◽  
Radio Observations ◽  
Radio Brightness ◽  
Lunar Occultation ◽  
Terrestrial Atmosphere ◽  
Accurate Position ◽  
The Crab Nebula

Observations of a lunar occultation of a radio source may provide information concerning both the distribution of radio “brightness” across the source and its accurate position. For sources of which these results are already fairly well known, observations at long wavelengths may be used to derive the density of the lunar atmosphere [1]. During recent years two such occultations have been observed at Cambridge: one, the occultation of IC 443, the large-diameter radio source in the constellation of Gemini, from which the density of the lunar atmosphere was estimated to be less than 10–12 of that of the density of the terrestrial atmosphere [2] and [3]; and two, the occultation of the Crab nebula on 1956 January 24 [4].

scholarly journals Lunar Occultation of the Radio Source CTA 21

Nature ◽  
1965 ◽  
Vol 207 (4996) ◽  
pp. 511-511 ◽  
Author(s):  
R. W. CLARKE ◽  
R. A. BATCHELOR
Keyword(s):  
Radio Source ◽  
Lunar Occultation

A Centaurus A : Spectra of the Optical Filament

1975 ◽  
Vol 2 (6) ◽  
pp. 366-367 ◽  
Author(s):  
B.A. Peterson ◽  
R.J. Dickens ◽  
R.D. Cannon
Keyword(s):  
Radio Source ◽  
Elliptical Galaxy ◽  
Brightness Distribution ◽  
Radio Brightness ◽  
Dust Lane ◽  
X Ray ◽  
The Galaxy ◽  
Centaurus A

The radio source, Cen A, is large and complex with many peaks in the brightness distribution over an area about 4 x 10 degrees. The peculiar elliptical galaxy NGC 5128 lies between the two strong inner radio brightness peaks and is centred on a weaker central radio source. This radio source is in the centre of the dust lane which divides the galaxy and may be related to the infrared, X-ray and γ-ray sources.

Lunar Occultation of the Radio Source 3C 273

Nature ◽  
1964 ◽  
Vol 201 (4921) ◽  
pp. 755-756 ◽  
Author(s):  
J. A. BAILEY ◽  
N. J. B. A. BRANSON ◽  
B. ELSMORE ◽  
P. A. G. SCHEUER
Keyword(s):  
Radio Source ◽  
Lunar Occultation

scholarly journals Vlbi Observations of the Compact Components in M82

1986 ◽  
Vol 7 ◽  
pp. 661-663
Author(s):  
N. Bartel ◽  
M.I. Ratner ◽  
A.E.E. Rogers ◽  
I.I. Shapiro ◽  
R.J. Bonometti ◽  
...  
Keyword(s):  
Central Region ◽  
Brightness Distribution ◽  
Radio Brightness ◽  
Upper Limit ◽  
Vlbi Observations ◽  
Radio Brightness Distribution ◽  
The Galaxy ◽  
Considerable Detail

The nearby IrrII galaxy M82 (3C 231, NGC3034) is known to have a complex, very elongated radio brightness distribution in the central region of the galaxy (e.g., Kronberg and Wilkinson 1975). Because of the galaxy’s proximity (distance ~ 3.3 Mpc; Tammann and Sandage 1968), the brightness distribution can be investigated in considerable detail. Recently Unger et al. (1984) and Kronberg, Biermann, and Schwab (1985; see also Kronberg 1986) distinguished about 20 compact components in the central region, most of them unresolved with an upper limit on their angular sizes of ~ 150 mas corresponding to an upper limit on their linear sizes of ~ 2 pc. About half of the components were observed at more than one frequency and at several epochs and were found typically to have steep spectra between 5 and 15 GHz and (Kronberg and Sramek 1985) slowly decreasing flux densities.

Lunar Occultation of a Radio Star and the Derivation of an Upper Limit for the Density of the Lunar Atmosphere

Nature ◽  
1955 ◽  
Vol 176 (4479) ◽  
pp. 457-458 ◽  
Author(s):  
B. ELSMORE ◽  
G. R. WHITFIELD
Keyword(s):  
Lunar Occultation ◽  
Upper Limit

scholarly journals Lunar Occultation of a Radio Source

Nature ◽  
1961 ◽  
Vol 191 (4783) ◽  
pp. 58-58 ◽  
Author(s):  
C. HAZARD
Keyword(s):  
Radio Source ◽  
Lunar Occultation

Upper Limit of 3.3 Astronomical Units to the Diameter of the Galactic Center Radio Source Sgr A*

Science ◽  
1993 ◽  
Vol 262 (5138) ◽  
pp. 1414-1416 ◽  
Author(s):  
D. C. Backer ◽  
J. A. Zensus ◽  
K. I. Kellermann ◽  
M. Reid ◽  
J. M. Moran ◽  
...  
Keyword(s):  
Radio Source ◽  
Galactic Center ◽  
Upper Limit ◽  
Sgr A

scholarly journals Extreme Emission Line Outflows in the GPS Source 4C 12.50 (PKS 1345+12)

2003 ◽  
Vol 20 (1) ◽  
pp. 25-27 ◽  
Author(s):  
J. Holt ◽  
C. N. Tadhunter ◽  
R. Morganti
Keyword(s):  
High Resolution ◽  
Emission Line ◽  
Radio Source ◽  
Spectral Coverage ◽  
La Palma ◽  
Upper Limit ◽  
Line Region ◽  
The Galaxy ◽  
William Herschel

AbstractWe present high resolution spectra (0.7 Å/pix) of the GPS source 4C 12.50 with large spectral coverage (˜4500 Å) taken with the 4.2 m William Herschel Telescope, La Palma. The slit was aligned along PA 160° to include the nucleus and emission line region to the NW. An asymmetric halo extending 20 kpc NW and 12 kpc SE from the nucleus is clearly seen. At the position of the nucleus we observe unusually broad forbidden emission line components (broadest component: FWHM ˜ 2000 km s−1), blue shifted by up to 2000 km s−1 with respect to the halo of the galaxy and HI absorption. We interpret this as material in outflow. We measure E(B–V) = 1.44 for the broadest, most kinematically disturbed component, corresponding to an actual Hβ flux 130 times brighter than that measured. We calculate an upper limit for the mass of the line emitting gas of order 106 M⊙ for both the intermediate and broad components. Our results are consistent with 4C 12.50 being a young radio source.

Depolarization silhouettes and the filamentary structure in the radio source Fornax A

1989 ◽  
Vol 346 ◽  
pp. L17 ◽  
Author(s):  
Edward B. Fomalont ◽  
Kathleen A. Ebneter ◽  
Wil J. M. van Breugel ◽  
Ronald D. Ekers
Keyword(s):  
Radio Source ◽  
Filamentary Structure
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