scholarly journals Occupation of the Crab Nebula by the Solar Corona in June 1963

Nature ◽  
1963 ◽  
Vol 200 (4908) ◽  
pp. 766-766 ◽  
Author(s):  
J. D. WYNDHAM ◽  
B. G. CLARK
Keyword(s):  
Solar Corona ◽  
Crab Nebula ◽  
The Crab Nebula

scholarly journals 58. Results of observations of the scattering of radio waves by the electronic inhomogeneities of the solar corona

1957 ◽  
Vol 4 ◽  
pp. 313-317
Author(s):  
V. V. Vitkevitch
Keyword(s):  
Solar Corona ◽  
Radio Source ◽  
Crab Nebula ◽  
New Method ◽  
Radio Waves ◽  
The Crab Nebula

A new method for the investigation of the solar corona, suggested by us (Vitkevitch, 1951) [1], consists of observing the radio source identified with the Crab nebula (NGC 1952; α = 05h 31m 40s, δ = 22° 10′) when it is covered by the solar corona. This occurs every year on 14–15 June.

scholarly journals Occultations of the Crab Nebula by the Solar Corona in June 1957 and 1958

1959 ◽  
Vol 12 (2) ◽  
pp. 134 ◽  
Author(s):  
OB Slee
Keyword(s):  
Solar Corona ◽  
Large Scale ◽  
Crab Nebula ◽  
Angular Separation ◽  
Pencil Beam ◽  
Scattering Process ◽  
Short Term ◽  
Transmission Properties ◽  
The Crab Nebula ◽  
Comparable Magnitude

A description is given of some observations of the occultations of the Crab nebula by the solar corona in June 1957 and 1958, obtained with pencil-beam, fan-beam, and interferometer-type instruments. It is shown that the distribution of 85� 5 Mc/s radiation on days when the angular separation is less than 10 solar radii is not consistent with a symmetrical scattering process. Better agreement is obtained by postulating the existence of scattering and regular refraction of comparable magnitude. Certain unexplained features of the pencil-beam distributions indicate that large-scale electron irregularities may be important in the scattering and refraction process. Additional evidence is presented for very short-term changes in the transmission properties of the corona.

Coronal Broadening of the Crab Nebula 1969-71: Observations

1972 ◽  
Vol 2 (2) ◽  
pp. 84-86 ◽  
Author(s):  
R. G. Blesing ◽  
P. A. Dennison
Keyword(s):  
Solar Cycle ◽  
Solar Corona ◽  
Crab Nebula ◽  
Two Dimensional ◽  
Dimensional Image ◽  
Two Dimensional Image ◽  
The Crab Nebula

A description was given in a previous paper of the first observations of the two-dimensional image of the Crab Nebula as it became broadened by the solar corona in June 1969. In this paper we describe further observations at 80 MHz during 1970 and 1971, again using the CSIRO Radioheliograph at Culgoora, N.S.W., and we discuss the derived values for radial and tangential broadening in relation to previous work at various phases of the solar cycle. Other methods of observing angular broadening have generally employed two or three interferometers at different position angles, and only the simplest model for the image could be assumed in interpreting the results. The radioheliograph, however, has the advantage of recording the complete two-dimensional image and also, simultaneously, the surrounding background.

Occultation of the Crab Nebula by the Solar Corona in June 1962

Nature ◽  
1963 ◽  
Vol 197 (4870) ◽  
pp. 885-886 ◽  
Author(s):  
SANTIMAY BASU ◽  
JOHN CASTELLI
Keyword(s):  
Solar Corona ◽  
Crab Nebula ◽  
The Crab Nebula

Observations of the Occulation of the Crab Nebula by the Solar Corona at a Wavelength of 6 CM.

1964 ◽  
Vol 139 ◽  
pp. 404 ◽  
Author(s):  
M. P. Hughes ◽  
D. Downes ◽  
C. Murray
Keyword(s):  
Solar Corona ◽  
Crab Nebula ◽  
The Crab Nebula

scholarly journals Time Variability of the Dispersion of the Crab Nebula Pulsar

1971 ◽  
Vol 46 ◽  
pp. 114-117 ◽  
Author(s):  
J. M. Rankin ◽  
J. A. Roberts
Keyword(s):  
Solar Corona ◽  
Optical Activity ◽  
Crab Nebula ◽  
Time Variability ◽  
Dispersion Measure ◽  
Decay Times ◽  
Transient Events ◽  
The Crab Nebula

The dispersion of the Crab nebula pulsar was measured as a function of time from 10 May 1969 to 24 July 1970. Transient events occurred in the middle of June each year which coincided with the occultation of the pulsar by the solar corona. In addition there were 2 or 3 distinct events which produced enhancements of several times 1016 electrons cm-2; these were characterized by rise times of about 50 days and decay times several times longer. One event correlated with the frejump of the pulsar at the end of September 1969 and with the observation of optical activity in the quency nebula. A discussion is given of the interpretation of the variations in dispersion measure.

scholarly journals The scattering of radio waves in the solar corona

1959 ◽  
Vol 9 ◽  
pp. 268-273 ◽  
Author(s):  
A. Hewish
Keyword(s):  
Solar Corona ◽  
Crab Nebula ◽  
Angular Diameter ◽  
Radio Waves ◽  
The Crab Nebula ◽  
The Waves

The angular diameter of the Crab nebula is considerably increased when it is viewed through the solar corona. This effect is due to the scattering of the waves by coronal irregularities and its study gives some indication of the nature of the outermost corona. This paper is a summary of observations carried out each year at Cambridge for the period 1952 to 1958 inclusive.

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