The Brightness Temperature of Venus and the Absolute Flux-Density Scale at 608 MHZ

1973 ◽  
Vol 183 ◽  
pp. 1081 ◽  
Author(s):  
Duane O. Muhleman ◽  
Glenn L. Berge ◽  
Glenn S. Orton
Keyword(s):  
Brightness Temperature ◽  
Flux Density ◽  
Absolute Flux ◽  
The Absolute ◽  
Density Scale

A specialized torsion balance designed to measure the absolute flux density of hyperthermal molecular beams containing reactive species

1996 ◽  
Vol 67 (5) ◽  
pp. 1781-1789 ◽  
Author(s):  
Steven R. Cook ◽  
Mark A. Hoffbauer ◽  
Jon B. Cross ◽  
Hermann Wellenstein ◽  
Manfred Fink
Keyword(s):  
Flux Density ◽  
Molecular Beams ◽  
Reactive Species ◽  
Torsion Balance ◽  
Absolute Flux ◽  
The Absolute

scholarly journals A circular polarization survey for radio stars with the Australian SKA Pathfinder

2021 ◽  
Vol 502 (4) ◽  
pp. 5438-5454
Author(s):  
Joshua Pritchard ◽  
Tara Murphy ◽  
Andrew Zic ◽  
Christene Lynch ◽  
George Heald ◽  
...  
Keyword(s):  
Radio Emission ◽  
Brightness Temperature ◽  
Circular Polarization ◽  
Flux Density ◽  
Wide Band ◽  
M Dwarfs ◽  
Square Kilometre Array ◽  
Population Statistics ◽  
Chemically Peculiar ◽  
Radio Stars

ABSTRACT We present results from a circular polarization survey for radio stars in the Rapid ASKAP Continuum Survey (RACS). RACS is a survey of the entire sky south of δ = +41○ being conducted with the Australian Square Kilometre Array Pathfinder telescope (ASKAP) over a 288 MHz wide band centred on 887.5 MHz. The data we analyse include Stokes I and V polarization products to an RMS sensitivity of 250 μJy PSF−1. We searched RACS for sources with fractional circular polarization above 6 per cent, and after excluding imaging artefacts, polarization leakage, and known pulsars we identified radio emission coincident with 33 known stars. These range from M-dwarfs through to magnetic, chemically peculiar A- and B-type stars. Some of these are well-known radio stars such as YZ CMi and CU Vir, but 23 have no previous radio detections. We report the flux density and derived brightness temperature of these detections and discuss the nature of the radio emission. We also discuss the implications of our results for the population statistics of radio stars in the context of future ASKAP and Square Kilometre Array surveys.

scholarly journals Properties of Faculae from Observations Near the Opacity Minimum

1994 ◽  
Vol 154 ◽  
pp. 23-27
Author(s):  
P Foukal ◽  
T Moran
Keyword(s):  
Magnetic Flux ◽  
Brightness Temperature ◽  
Flux Density ◽  
Flux Tube ◽  
Angular Resolution ◽  
Negative Contrast ◽  
Active Regions ◽  
Disk Center ◽  
Quantitative Comparison ◽  
Magnetic Flux Density

Imaging of active regions in continuum around 1.6 μm shows that many facular regions are less bright than the photosphere when observed nearer to disk center than μ = cos θ ~ 0.75. The contrast of these dark faculae increases with magnetic flux above a threshold of approximately 2 × 1018 Mx. This explains why not all faculae are dark at 1.6 μm, since the magnetic flux density in many regions of bright Ca K plage emission falls below this threshold. After correction for blurring, the typical contrast value is about 4-5%, so the brightness temperature deficit is about 130 K. Faculae are brighter than the photosphere at 1.63 μm nearer to the limb than μ ~ 0.5. The negative contrast of dark faculae may arise from cooling of the surrounding photosphere, or from increased visibility of cool layers of the facular flux tube itself. Quantitative comparison of these IR data with MHD models awaits calculation of flux tube contrasts at realistic angular resolution.

scholarly journals The UV Spectrum of W Cep.

1980 ◽  
Vol 88 ◽  
pp. 549-553
Author(s):  
R. Faraggiana
Keyword(s):  
Uv Spectrum ◽  
Absolute Flux ◽  
The Absolute

IUE spectra of VV Cep have been obtained in 1978 and 1979 during the chromospheric phase of the eclipse. The profiles of the Mg II resonance lines differ from one another and this peculiarity, common to other M type supergiants, is examined. The value of Mv derived from the extension of the Wilson and Bappu relation to Mg II lines is compared with other determinations. The variation of the absolute flux in the 1200-2000 Å range is presented.

scholarly journals Characterisation of the MALT90 Survey and the Mopra Telescope at 90 GHz

2013 ◽  
Vol 30 ◽  
Author(s):  
J. B. Foster ◽  
J. M. Rathborne ◽  
P. Sanhueza ◽  
C. Claysmith ◽  
J. S. Whitaker ◽  
...  
Keyword(s):  
Time Of Day ◽  
Repeated Observations ◽  
Absolute Flux ◽  
The Absolute ◽  
Flux Calibration

AbstractWe characterise the Millimetre Astronomy Legacy Team 90 GHz Survey (MALT90) and the Mopra telescope at 90 GHz. We combine repeated position-switched observations of the source G300.968+01.145 with a map of the same source in order to estimate the pointing reliability of the position-switched observations and, by extension, the MALT90 survey; we estimate our pointing uncertainty to be 8 arcsec. We model the two strongest sources of systematic gain variability as functions of elevation and time-of-day and quantify the remaining absolute flux uncertainty. Corrections based on these two variables reduce the scatter in repeated observations from 12%–25% down to 10%–17%. We find no evidence for intrinsic source variability in G300.968+01.145. For certain applications, the corrections described herein will be integral for improving the absolute flux calibration of MALT90 maps and other observations using the Mopra telescope at 90 GHz.

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