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. 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.

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 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 Solar Brightness Distribution at a Wavelength of 60 Centimetres. II. Localized Radio Bright Regions

1958 ◽  
Vol 11 (3) ◽  
pp. 338 ◽  
Author(s):  
G Swarup ◽  
R Parthasarathy
Keyword(s):  
Solar Cycle ◽  
Solar Radiation ◽  
Solar Disk ◽  
Brightness Distribution ◽  
The Sun ◽  
Minimum Period ◽  
Simple Interpretation ◽  
Solar Brightness ◽  
Low Activity

The localized radio bright regions on the Sun which give rise to a slowly varying component of the solar radiation were studied at a wavelength of 60 cm, using a 32-aerial interferometer with a beamwidth of 8�7 min of arc. The observations were undertaken during July 1954 to March 1955 and were limited in number due to this being a minimum period of the solar cycle. The low activity, however, provided the advantage of simple interpretation as often only one region was present on 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.

scholarly journals The Radio Brightness Distribution on the Sun at 21 cm from Combined Eclipse and Pencil?Beam Observations

1961 ◽  
Vol 14 (3) ◽  
pp. 403 ◽  
Author(s):  
T Krishnan ◽  
NR Labrum
Keyword(s):  
High Resolution ◽  
High Sensitivity ◽  
Brightness Distribution ◽  
Pencil Beam ◽  
The Sun ◽  
Radio Brightness ◽  
Radio Brightness Distribution ◽  
Grating Interferometer

A study of the brightness distribution on the Sun at 21-cm wavelength on April 8, 1959, is described. High resolution observations were made of the partial eclipse on that day with a simple radiometer of high sensitivity. The brightness distribution of the uneclipsed Sun at the same wavelength was obtained using a cross-grating interferometer, which enabled the bright regions to be located accurately.

Synoptic maps in three wavelengths of the Chromospheric Telescope

2018 ◽  
Vol 14 (A30) ◽  
pp. 339-341
Author(s):  
Andrea Diercke ◽  
Carsten Denker
Keyword(s):  
Time Series ◽  
Solar Cycle ◽  
Solar Disk ◽  
The Sun ◽  
Observational Period ◽  
Quiet Sun ◽  
Solar Cycle 24 ◽  
Cycle 24 ◽  
Spectral Ranges ◽  
Full Disk

Abstracthe Chromospheric Telescope (ChroTel) observes the entire solar disk since 2011 in three different chromospheric wavelengths: Hα, Ca ii K, and He i. The instrument records full-disk images of the Sun every three minutes in these different spectral ranges. The ChroTel observations cover the rising and decaying phase of solar cycle 24. We started analyzing the ChroTel time-series and created synoptic maps of the entire observational period in all three wavelength bands. The maps will be used to analyze the poleward migration of quiet-Sun filaments in solar cycle 24.

Evidence on Chromospheric Structure from Observations of Solar Brightness Distribution at Millimetre Wavelengths

1978 ◽  
Vol 3 (4) ◽  
pp. 256-259 ◽  
Author(s):  
N. R. Labrum
Keyword(s):  
Brightness Distribution ◽  
Aperture Synthesis ◽  
The Other ◽  
Solar Chromosphere ◽  
Quiet Sun ◽  
Preliminary Discussion ◽  
Eclipse Observation ◽  
Solar Brightness ◽  
Chromospheric Structure ◽  
Important Test

Observations of the distribution of millimetre-wavelength brightness over the quiet Sun provide an important test of models of the solar chromosphere. The author and colleagues have recently carried out two investigations of the quiet-Sun brightness at 3 mm wavelength — one by means of a total eclipse observation (Labrum et al. 1978) and the other by aperture synthesis with a two-element interferometer (Archer et al. 1978). I present here a preliminary discussion of these and other measurements of millimetre-wavelength brightness distributions and of their interpretation in terms of chromospheric structure.

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.

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