scholarly journals Galactic Radiation at Radio Frequencies. VIII. Discrete Sources at 100 Mc/s Between Declinations +50° and ?50°

1954 ◽  
Vol 7 (1) ◽  
pp. 110 ◽  
Author(s):  
JG Bolton ◽  
GJ Stanley ◽  
OB Slee
Keyword(s):  
Flux Density ◽  
Radio Frequencies ◽  
The Individual ◽  
Galactic Radiation

One hundred and four discrete sources have been found from a survey covering declinations +50 to ?50�. The individual sources are compared in position and flux density with those of previous surveys. The observed distribution shows the concentration of sources of all brightnesses to the galactic equator found by Brown and Hazard (1953) and the concentration of the bright sources to the equator found by Mills (1952a, 1952b, 1952c).

scholarly journals Multi-frequency pulsar studies at high radio frequencies

1996 ◽  
Vol 160 ◽  
pp. 279-282
Author(s):  
Michael Kramer ◽  
Kiriaki M. Xilouris
Keyword(s):  
Magnetic Field ◽  
Flux Density ◽  
Stellar Surface ◽  
Active Part ◽  
Frequency Range ◽  
Density Spectrum ◽  
Density Measurements ◽  
Radio Frequencies ◽  
Dipolar Structure ◽  
The Magnetic Field

AbstractWe report flux density measurements, polarimetric and timing observations of pulsars made at the highest radio frequencies to date, covering the widest frequency range from 1.4 GHz to 86 GHz. We find that the magnetic field maintains its dipolar structure throughout the active part of the magnetosphere, a region located close to the stellar surface and confined to a small slab of a few stellar radii. The change in width and shape of pulse profiles saturates at mm-wavelengths while the depolarization accelerates, leading to almost completely depolarized emission. Two pulsars seem to exhibit a turn-up in their flux density spectrum at mm-wavelengths.

scholarly journals Galactic Radiation at Radio Frequencies. V. The Sea Interferometer

1953 ◽  
Vol 6 (4) ◽  
pp. 420 ◽  
Author(s):  
JG Bolton ◽  
OB Slee
Keyword(s):  
Radio Frequencies ◽  
Galactic Radiation

The factors involved in the study of discrete sources of galactic noise by the sea interferometer are discussed. Three new forms of sea interferometer which increase the effectiveness of this technique are described.

scholarly journals Galactic Radiation at Radio Frequencies. VII. Discrete Sources with Large Angular Widths

1954 ◽  
Vol 7 (1) ◽  
pp. 96 ◽  
Author(s):  
JG Bolton ◽  
KC Westfold ◽  
GJ Stanley ◽  
OB Slee
Keyword(s):  
Angular Width ◽  
Radio Frequencies ◽  
Galactic Radiation

Observations with three forms of equipment have revealed the existence of a number of sources of angular width more than 1�.

scholarly journals An effective parameterization to quantify multiple solute flux breakthrough curves

2014 ◽  
Vol 11 (6) ◽  
pp. 6993-7017
Author(s):  
E. Bloem ◽  
M. de Gee ◽  
G. H. de Rooij
Keyword(s):  
Solute Transport ◽  
Flux Density ◽  
Breakthrough Curves ◽  
Solute Flux ◽  
Spatial Effects ◽  
Solute Fluxes ◽  
Spatial Aspect ◽  
Temporal Aspect ◽  
Temporal And Spatial ◽  
The Individual

Abstract. To understand soil and groundwater contamination we study the temporal and spatial aspects of solute transport in the unsaturated zone. One monitoring instrument that captures both aspects is the multi-compartment sampler (MCS). With the MCS developed by Bloem et al. (2010) we are able to measure the downward solute fluxes in 100 compartments at the depth of installation of the MCS, with a minimal disturbance of the flow field. Over time this dataset results in 100 individual solute flux breakthrough curves (BTCs) (temporal aspect). Sorting the BTCs in descending order of solute mass gives the spatial solute distribution curve (spatial aspect). We present a method to quantitatively characterize datasets gathered with MCS (or single samplers installed at multiple locations in a field at the same depth). The method approximates the full set of breakthrough curves using only a single function with four to eight parameters, which combines both temporal and spatial effects of solute transport in soils. This is achieved by modeling the scaled solute flux density breakthrough curves (BTCF) for each compartment as the solution of a conventional one-dimensional equilibrium convection disperion equation (CDE), without modifications. We detect and parameterize any relationships between the resulting transport velocities and dispersion coefficients of the individual BTCFs. Finally the spatial aspect is parameterized using the Beta distribution. This method is based on the flux density BTCs directly, which for transport phenomena is preferred over solute concentrations. In three experiments on undisturbed soils, the resulting approximation matched the data well.

scholarly journals Galactic Radiation at Radio Frequencies. VI. Low Altitude Scintillations of the Discrete Sources

1953 ◽  
Vol 6 (4) ◽  
pp. 434 ◽  
Author(s):  
JG Bolton ◽  
OB Slee ◽  
GJ Stanley
Keyword(s):  
Diurnal Variations ◽  
Scintillation Index ◽  
Seasonal Component ◽  
Seasonal And Diurnal Variations ◽  
Low Altitude ◽  
Radio Frequencies ◽  
Galactic Radiation

A study has been made of the scintillations of four discrete sources at altitudes of from 0 to 10�. The observations cover the years 1947?1951 and were made at various frequencies in the range 40?300 Mc/s. It was found that the scintillation index, a measure of the amplitude of the scintillations, (1) increases with increasing wavelength, (2) decreases rapidly with increasing altitude, (3) shows seasonal and diurnal variations, the seasonal component having minima near the equinoxes and the diurnal component near dawn and sunset. The scintillation rate or the number of scintillations per minute (1) is different for sources of different declination, (2) is independent of wavelength. In the case of the Cygnus source, the data for which are the most extensive, the rate increases and the decline in the scintillation index with altitude is less rapid during the winter months.

scholarly journals The analysis of the possible thermal emission at radio frequencies from an evolved supernova remnant HB 3 (G132.7+1.3): Revisited

2008 ◽  
pp. 67-71 ◽  
Author(s):  
D. Onic ◽  
D. Urosevic
Keyword(s):  
Flux Density ◽  
Molecular Cloud ◽  
Supernova Remnant ◽  
Thermal Emission ◽  
Radio Spectrum ◽  
Thermal Component ◽  
Support Interaction ◽  
Density Values ◽  
H Ii Region ◽  
Radio Frequencies

It has recently been reported that some of the flux density values for an evolved supernova remnant (SNR) HB 3 (G132.7+1.3) are not accurate enough. In this work we therefore revised the analysis of the possible thermal emission at radio frequencies from this SNR using the recently published, corrected flux density values. A model including the sum of non-thermal (purely synchrotron) and thermal (bremsstrahlung) components is applied to fit the integrated radio spectrum of this SNR. The contribution of thermal component to the total volume emissivity at 1 GHz is estimated to be ? 37%. The ambient density is also estimated to be n ? 9 cm-3 for T = 104 K. Again we obtained a relatively significant presence of thermal emission at radio frequencies from the SNR, which can support interaction between SNR HB 3 and adjacent molecular cloud associated with the H ii region W3. Our model estimates for thermal component contribution to total volume emissivity at 1 GHz and ambient density are similar to those obtained earlier (? 40 %, ? 10 cm-3 ). It is thus obvious that the corrected flux density values do not affect the basic conclusions.

scholarly journals Main Pulse-Interpulse Correlation and Mode Changing in PSR 1055-52

1992 ◽  
Vol 128 ◽  
pp. 261-264
Author(s):  
James D. Biggs
Keyword(s):  
Flux Density ◽  
Main Pulse ◽  
Pulse Profile ◽  
Rotation Axes ◽  
Peak Flux ◽  
The Individual ◽  
Magnetic Poles

AbstractWe have studied the individual pulses from PSR 1055–52, a pulsar which has a strong interpulse. Their properties, and those of the average pulse profile are consistent with an emission geometry in which the magnetic and rotation axes are nearly perpendicular. That is, we are observing both magnetic poles of this pulsar. A correlation between the emission from the two magnetic poles was found wherein a strong interpulse is followed by a strong main pulse. Also, the main pulse appears to undergo mode changes that are primarily characterized by a change in the peak flux density of component I.

scholarly journals SN 1987A at Radio Wavelengths

2005 ◽  
Vol 192 ◽  
pp. 89-95
Author(s):  
L. Staveley-Smith ◽  
R.N. Manchester ◽  
B.M. Gaensler ◽  
M.J. Kesteven ◽  
A.K. Tzioumis ◽  
...  
Keyword(s):  
Flux Density ◽  
Spectral Index ◽  
Supernova Remnant ◽  
Expansion Rate ◽  
Radio Luminosity ◽  
Sn 1987A ◽  
Radio Imaging ◽  
Radio Frequencies ◽  
Compact Array

SummarySN1987A has an intrinsic radio luminosity some four orders of magnitude less than SN1993J at maximum, largely a reflection of the tenuous wind . from the progenitor of SN1987A before explosion. Both remnants have an edge-brightened, ring-like morphology though, in the case of SN1987A, the expansion rate is currently only around 3500 km s−1. The flux density of the remnant of SN1987A continues to rise at all measured radio frequencies. Its spectral index is gradually flattening, indicating its transition into the supernova remnant phase. A campaign to increase the resolution of radio imaging by observing at higher frequencies is underway with the Australia Telescope Compact Array (ATCA).

scholarly journals On the patchiness of the individual pulse spectra at the very low radio frequencies

2017 ◽  
Vol 13 (S337) ◽  
pp. 412-413
Author(s):  
Xiaoxi Song ◽  
Vladislav Kondratiev ◽  
Anna Bilous
Keyword(s):  
Pulse Sequences ◽  
Low Frequency ◽  
Single Pulse ◽  
Radio Bursts ◽  
Individual Pulse ◽  
Recorded Signal ◽  
Highly Dispersed ◽  
Radio Frequencies ◽  
The Individual

AbstractWe have used sensitive LOw Frequency ARray (LOFAR) observations of PSR B0809+74 at 15–62 MHz to study the anomalously intensive pulses, first reported by Ulyanov et al. (2006) at 18–30 MHz. Similarly to Ulyanov et al., we found that the spectra of strong pulses consist of distinct bright patches. Moreover, these spectral patches were spotted to drift upwards in frequency over the course of several pulse sequences. We established that this drift is not pulsar-intrinsic, but is caused by the broadband ~20 second-long enhancements of recorded signal, which influenced the dispersed tracks of several pulses at once. We speculate on the cause of such enhancements (i.e. propagation or telescope-related) and the ramifications they bring to the single-pulse studies at the very low radio frequencies. Depending on the origin, the phenomenon may also affect the analysis of highly dispersed single pulses at higher radio frequencies, e.g. Fast Radio Bursts.

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