scholarly journals The Distribution of Radio Brightness over the Solar Disk at a Wavelength of 21 Centimetres. III. The Quiet Sun ? Two-Dimensional Observations

1955 ◽  
Vol 8 (4) ◽  
pp. 474 ◽  
Author(s):  
WN Christiansen ◽  
JA Warburton
Keyword(s):  
Solar Disk ◽  
Fourier Method ◽  
Brightness Distribution ◽  
Sunspot Activity ◽  
Polar Regions ◽  
Two Dimensional ◽  
Radio Brightness ◽  
One Dimensional ◽  
Quiet Sun ◽  
Coronal Electron

A distribution of solar radio brightness at a wavelength of 21 cm has been derived from observations made during the period of low sunspot activity from 1952 to 1954. The observations were made using two multiple interferometers arranged at right angles; this enabled the solar disk to be scanned in many different directions. The derived one-dimensional profiles of the quiet Sun for these various scanning directions were combined and a Fourier method adopted to derive a two-dimensional brightness distribution. The distribution shows marked limb-brightening in the equatorial zones but none in the polar regions. The contours of brightness are in general conformity with those expected from a solar atmosphere having a coronal electron density distribution of the kind proposed by van de Hulst for the period of minimum sunspot activity.

scholarly journals Solar Brightness Distribution at a Wavelength of 60 Centimetres. I. The Quiet Sun

1955 ◽  
Vol 8 (4) ◽  
pp. 487 ◽  
Author(s):  
G Swarup ◽  
R Parthasarathy
Keyword(s):  
Solar Cycle ◽  
Brightness Distribution ◽  
Central Meridian ◽  
The Sun ◽  
Two Dimensional ◽  
Radio Brightness ◽  
One Dimensional ◽  
Quiet Sun ◽  
Solar Brightness

A multiple-element interferometer has been employed to determine one-dimensional distributions of radio brightness over the quiet Sun at a wavelength of 60 cm for scanning directions varying from 90� to 60� with respect to the central meridian of the Sun. These observations have been compared with measurements by other workers at the same, or nearly the same, wavelength. The present observations are reasonably consistent with the two-dimensional brightness distribution derived recently by O'Brien and Tandberg-Hanssen with a two-aerial interferometer, but do not agree with the earlier results of Stanier at the same wavelength. The disagreement, largely the absence of the theoretically predicted limb-brightening in Stanier's results, may reflect actual changes in the Sun over the solar cycle. However, the possibility of localized disturbed regions affecting Stanier's results for the quiet Sun cannot be eliminated.

scholarly journals The Distribution Of Radio Brightness Over The Solar Disk At A Wavelength Of 21 Centimetres. I. A New Highly Directional Aerial System

1953 ◽  
Vol 6 (2) ◽  
pp. 190 ◽  
Author(s):  
WN Christiansen ◽  
JA Warburton
Keyword(s):  
Transmission Lines ◽  
Solar Disk ◽  
Brightness Distribution ◽  
Resolving Power ◽  
Radio Brightness ◽  
One Dimensional ◽  
Multiple Beams ◽  
Rotation Of The Earth ◽  
Very High ◽  
East West

A new aerial system of very high resolving power has been designed for use in determining the distribution of radio brightness across the solar disk at a wavelength of 21 cm. Thirty-two aerials with paraboloidal reflectors are evenly spaced in an east-west direction over a distance of about 700 ft., and are connected by a branching system of balanced open-wire transmission lines to a receiver. The aerial system produces multiple beams each 3' of arc wide and spaced 1.7� apart. The rotation of the Earth causes one after another of the aerial beams to scan the disk of the Sun. The record obtained from the radio receiver gives a one-dimensional brightness distribution over the solar disk.

scholarly journals The Distribution of Radio Brightness over the Solar Disk at a Wavelength of 21 Centimetres. II. The Quiet Sun ? One-dimensional Observations

1953 ◽  
Vol 6 (3) ◽  
pp. 262 ◽  
Author(s):  
WN Christiansen ◽  
JA Warburton
Keyword(s):  
Brightness Distribution ◽  
Lower Envelope ◽  
Solar Model ◽  
Radio Brightness ◽  
Preliminary Calculation ◽  
One Dimensional ◽  
Quiet Sun ◽  
Dimensional Distribution ◽  
Small Change ◽  
Shape And Size

Daily records of one-dimensional distribution of radio brightness over the Sun are obtained in the way described in Part I of this series (Christiansen and Warburton 1953). When superimposed, these records show a well-marked lower envelope which remains substantially the same, in shape and size, over a period of months. This envelope gives the brightness distribution over the "quiet" Sun. The direction of scan, with respect to the position of. the solar axis, changes during a year by more than 50�. The very small change in shape of the envelope during this period suggests that for purposes of preliminary calculation the brightness distribution may be assumed to be circularly symmetrical. The radial distribution of brightness, calculated on this basis, is found to show marked limb-brightening and to be consistent with the calculated brightness distribution for a simple solar model in which the assumed values of temperature and density are close to those commonly accepted.

Person Localization System Using Privacy-Preserving Sensor

2011 ◽  
Vol 103 ◽  
pp. 622-627 ◽  
Author(s):  
Shota Nakashima ◽  
Hui Min Lu ◽  
Kohei Miyata ◽  
Yuhki Kitazono ◽  
Serikawa Seiichi
Keyword(s):  
Low Cost ◽  
Video Camera ◽  
Brightness Distribution ◽  
Privacy Preserving ◽  
Two Dimensional ◽  
Texture Image ◽  
Localization System ◽  
One Dimensional ◽  
Two Dimensional Image ◽  
Simulation Results

A privacy-preserving sensor for person localization has been developed. In theory, the sensor can be constructed with a line sensor and cylindrical lens because only a one-dimensional brightness distribution is needed. However, a line sensor is expensive. In contrast, CMOS area sensors are low cost and are increasing in sensitivity according to recent rapid advancement in the technology. Therefore, we covered the CMOS area sensor physically so that it behaved as a line sensor, we substituted CMOS sensors for the line sensors in practice. The proposed sensor obtains a one-dimensional horizontal brightness distribution that is approximately equal to the integration value of each vertical pixel line of the two-dimensional image. It is impossible to restore the two-dimensional detail texture image from one-dimensional brightness distribution, although it obtains enough information to detect a person’s position and movement status. Thus, the privacy is protected. Moreover, the appearance of the proposed sensor is very different from the conventional video camera, so the psychological resistance of having a picture taken is reduced. In this work, we made the privacy preserving sensor practically, and verified whether a person’s state was able to be detected. The simulation results show that the proposed sensor can detect a present person’s state responsively without violating privacy.

Solar Radio Observations at 843 MHz

1989 ◽  
Vol 8 (2) ◽  
pp. 142-144 ◽  
Author(s):  
A. D. Gray ◽  
D. Campbell-Wilson ◽  
M. I. Large
Keyword(s):  
Solar Radio ◽  
Coronal Holes ◽  
Total Power ◽  
The Sun ◽  
Two Dimensional ◽  
Radio Observations ◽  
Radio Brightness ◽  
Partial Synthesis ◽  
One Dimensional ◽  
Exact Relationship

AbstractThe Molonglo Observatory Synthesis Telescope (MOST) has been used to observe the Sun with total-power fan-beams having a one-dimensional resolution of 41 arcsec at 843 MHz. The scans reveal clearly the rotation and evolution of the slowly-varying component as well as some burst activity. Low radio brightness features have also been identified, but the exact relationship between these features and coronal holes is, as yet, unclear. Several partial synthesis observations have been used to generate two-dimensional radioheliograms.

Techniques for Decimetre Wavelength Observations of Radio Plages and Bursts

1967 ◽  
Vol 1 (2) ◽  
pp. 55-55
Author(s):  
W. N. Christiansen
Keyword(s):  
Brightness Distribution ◽  
Resolving Power ◽  
The Sun ◽  
Two Dimensional ◽  
Radio Brightness ◽  
Field Station ◽  
Radio Brightness Distribution ◽  
The University

The first daily maps showing the two-dimensional radio brightness distribution over the Sun were produced at Fleurs ten years ago when the 64-antenna grating cross was completed. The maps had a resolution of 3′ arc at λ = 21 cm.When the Fleurs field station was given to the University by CSIRO in 1963 it was decided to use the antennas of the grating cross and add to them four or more larger antennas (45 ft diameter) to produce a pair of high resolving-power compound interferometers.

scholarly journals The Radio Brightness of the Quiet Sun at 21 cm Wavelength Near Sunspot Maximum

1960 ◽  
Vol 13 (4) ◽  
pp. 700 ◽  
Author(s):  
NR Labrum
Keyword(s):  
Active Regions ◽  
Residual Effects ◽  
High Angular Resolution ◽  
Radio Brightness ◽  
Sunspot Maximum ◽  
One Dimensional ◽  
Quiet Sun ◽  
Limits Of Error ◽  
Very High ◽  
Intense Radiation

An investigation has been made of the radio emission from the quiet Sun at 21� 2 em wavelength in 1958 (near sunspot maximum). Two different methods have been used, both involving observations with very high angular resolution, to distinguish between the quiet-Sun component and the radiation from localized active regions. In one method, the Sun was scanned with a narrow pencil-beam; in the other, a fan-shaped aerial beam was used to give one-dimensional strip scans. In both cases it was necessary, when analysing the data, to take into account the residual effects of the very intense radiation from the localized sources. The two independent measurements gave results which agree within the limits of error. The apparent disk temperature was found to be approximately 140 000 oK, or twice the value for the same wavelength at sunspot minimum.

scholarly journals The quiet sun at 88-cm wavelength

1959 ◽  
Vol 9 ◽  
pp. 107-107
Author(s):  
J. Firor
Keyword(s):  
Brightness Distribution ◽  
Lower Envelope ◽  
The Sun ◽  
One Dimensional ◽  
Quiet Sun ◽  
The One

An attempt has been made to measure the one-dimensional brightness distribution of the sun at 88-cm wavelength. Strip scans of the sun made with a 4′.8 fan beam have been superimposed and the lower envelope drawn, after the manner of Christiansen [1].

scholarly journals 50. Observations of brightness over the disk of the quiet sun at frequencies of 85, 500 and 1400 Mc./s.

1957 ◽  
Vol 4 ◽  
pp. 284-289
Author(s):  
J. L. Pawsey
Keyword(s):  
Radio Emission ◽  
Solar Disk ◽  
Thermal Emission ◽  
Large Range ◽  
Model Atmosphere ◽  
Brightness Distribution ◽  
Final Model ◽  
Quiet Sun ◽  
Comprehensive Information ◽  
Electron Density And Temperature

Observations of radio emission from the quiet sun, which is believed to be due to thermal emission from the ionized gases of the solar atmosphere, provide information about the electron density and temperature throughout the atmosphere. Comprehensive information requires observations, preferably of the brightness distribution over the solar disk, over a large range of wave-lengths. Because such observations are both difficult and tedious it is desirable that a final model atmosphere should be based on a pool of observations taken by independent methods and observers. The following are recent contributions to this pool from the Radiophysics Laboratory.

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