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Topic: Radio source


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In the News (Fri 1 Jan 10)

  
  Radio News Source|Sound bites|Copy|Psas|Current events|Release Service
For the anniversary of the first scheduled radio broadcast on November 2, we interviewed producers and reporters about their first radio broadcast.
Radio News Source is a web site that provides current, compelling, and newsworthy content to radio stations across the country and across the web.
Whether you want stories by topic, geographic region, or latest news, our site is organized to make it easy for you to navigate and find the news items you need right at your fingertips.
www.radionewssource.com   (468 words)

  
  Radio telescope - Wikipedia, the free encyclopedia
The largest radio telescope in Europe is the 100 meter diameter antenna in Effelsberg, Germany, which also was the largest fully steerable telecope for 30 years until the Green Bank Telescope was opened in 2000.
A typical size of the single antenna of a radio telescope is 25 metre, dozens of radio telescopes with comparable sizes are operated in radio observatories all over the world.
Grote Reber (December 22, 1911 – December 20, 2002) was one of the pioneers of radio astronomy.
en.wikipedia.org /wiki/Radio_telescope   (543 words)

  
 Radio source - Wikipedia, the free encyclopedia
Radio sources are objects in outer space that emit strong radio waves.
Radio emission comes from hot gas, electrons spiralling in magnetic fields and specific wavelengths emitted by atoms and molecules in space.
A few examples include neutral hydrogen and carbon monoxide, mostly found in spiral galaxies, and quasars (short for "quasi-stellar radio source"), which are point-like sources of radio waves and other kinds of electromagnetic radiation that are thought to be powered by supermassive fl holes in the centers of elliptical galaxies.
www.wikipedia.org /wiki/Radio_source   (252 words)

  
 Radio - Wikipedia, the free encyclopedia
Although the word 'radio' is used to describe this phenomenon, the transmissions which we know as television, radio, radar, and cell phone are all classed as radio frequency emissions.
Radio was used to pass on orders and communications between armies and navies on both sides in World War I; Germany used radio communications for diplomatic messages once its submarine cables were cut by the British.
Radio remote control: Use of radio waves to transmit control data to a remote object as in some early forms of guided missile, some early TV remotes and a range of model boats, cars and aeroplanes.
en.wikipedia.org /wiki/Radio   (4475 words)

  
 radio source Comparison Table   (Site not responding. Last check: 2007-11-04)
A radio source in Cassiopeia, the strongest extrasolar source in the sky, believed to be the remnant of a Type II supernova whose light reached Earth about 1667.
A radio source, a large broken shell 4°.5 in diameter, identified as a prehistoric supernova remnant.
A radio galaxy is usually a giant elliptical - the largest galaxy in a cluster - and is a strong emitter of synchrotron radiation.
www.csi.uottawa.ca:4321 /astronomy/radiosource_table.html   (357 words)

  
 WOMBAT Radio source predictions Version 1.0   (Site not responding. Last check: 2007-11-04)
PMN sources with apparently rising spectra were set to flat spectra and assigned a spectral index uncertainty of 0.5 since radio spectra that rise from 2.7 to 5 GHz typically turn over and fall thereafter.
For sources from the SGS catalog, we expect there to be an additional independent uncertainty at each frequency of a factor of 1.3 at frequencies below 150 GHz, a factor of 2 at frequencies between 150 and 300 GHz, and a factor of 3 at frequencies above 300 GHz.
The first 2206 sources in these files are from the SGS catalog; some of their positions are uncertain by 15', which will be remedied soon by comparison with higher-precision positions in the GB6 and PMN catalogs.
astron.berkeley.edu /wombat/foregrounds/radio.html   (770 words)

  
 Active Galaxies and Quasars - Radio Galaxies   (Site not responding. Last check: 2007-11-04)
Radio galaxies are best known for their extensive double radio sources, shining by synchrotron radiation as electrons spiral through magnetic fields at relativistic speeds.
These are of so-called Fanaroff-Riley (FR) type I, with radio lobes decreasing smoothly in intensity outwards from the central source - for the contrasting case of an FR II source, see the Cygnus A slide.
The radio source of 3C 315 is so tightly twisted that it takes on the shape nicknamed by Jacques Vallee and his Francophone collaborators as Papillon - the butterfly.
www.astr.ua.edu /keel/agn/vlamaps.html   (386 words)

  
 The Earth is a Strong Radio Source Even Without Man's Tinkering, Alaska Science Forum   (Site not responding. Last check: 2007-11-04)
Radio telescopes, such as the mammoth 1000 ft. diameter receiver at Arecibo Observatory in Puerto Rico, have enabled scientists to detect strong radio waves emanating from such familiar bodies as Jupiter and the Sun, and more elusive distant objects such as pulsars and quasars.
This holds especially true when it is considered that, although scientists can "see" and measure the waves from the extraterrestrial bodies from observatories on the surface of the earth, they are unable to detect the ones (except those artificially produced) that the earth itself propels into space.
We know, of course, that man-made radio and TV signals continually race outward into space, but it was not until 1974 that D.A. Gurnett of the University of Iowa reported, from satellite observations, that intense unidentified radio waves were also being emitted from the earth itself.
www.gi.alaska.edu /ScienceForum/ASF6/612.html   (377 words)

  
 No Title   (Site not responding. Last check: 2007-11-04)
The data reveal ``holes'' in the X-ray emission that are coincident with the radio lobes.
The data are consistent with the radio source displacing and compressing, and at the same time being confined by, the X-ray gas.
The pressure in the X-ray gas (the shells and surrounding cooler gas) is approximately an order of magnitude higher than the minimum pressure derived for the radio source, suggesting that an additional source of pressure is needed to support the radio plasma.
asc.harvard.edu /symposium_2001/CG/97clean/97clean.html   (194 words)

  
 Astronomers Detect Powerful Bursting Radio Source
The team has monitored the Galactic center for new transient sources and for variability in approximately 250 known sources, but the five bursts from the new radio source, named GCRT J1745-3009, were by far the most powerful seen.
The source of the bursts is transient Hyman noted.
One important clue to understanding the origin of the radio bursts is that the emission appears to be "coherent," Hyman said.
www.sciencedaily.com /releases/2005/03/050309125109.htm   (1075 words)

  
 Method of determining the direction of a radio source and radio interferometer system - Patent 4160252   (Site not responding. Last check: 2007-11-04)
Method of determining the direction of a radio source, wherein, using a circular array of aerials, a sinusoidal phase graph is determined and the direction of the radio source relative to a reference direction is determined from one or more zero crossings of the phase graph.
The technique of using radio interferometer pairs to determine the direction of a radio source is known and an arrangement is disclosed in, for example, German Offenlegungsschrift No. 2011147.
Because of the necessity to preserve at the intermediate frequency the relative phase differences between the signals from the aerials the receivers are all fed, in phase, with local oscillator energy LO from a source not shown.
www.freepatentsonline.com /4160252.html   (3886 words)

  
 APOD Search Results for "radio "
Radio Arc is connected to the Galactic center by strange curving filaments known as the Arches.
Radio (red) and optical emission (green) are brighter near the central regions where the x-rays seem to be absorbed by denser, cooler material on the side of the expanding debris cloud facing the Earth.
Impressively, the radio sources appear to be so small, less than about 600 light-years across in actual size, that they are thought to be associated with massive central fl holes in the distant deep field galaxies.
antwrp.gsfc.nasa.gov /cgi-bin/apod/apod_search?radio%2B   (10627 words)

  
 Astron. Astrophys. 349, 475-484 (1999)
The positions of the IR sources (triangles) are taken from Eiroa and Casali (1992).
The position of the X-ray source Ser-X3 is marked by a cross, with size 10" corresponding to the positional error given by P98.
The source is detected at all three dates, suggesting that the radio emission is stable, and if associated with a corona, quiescent.
aa.springer.de /papers/9349002/2300475/sc3.htm   (635 words)

  
 Astronomers Detect Powerful Bursting Radio Source: Discovery Points to New Class of Astronomical Objects
This radio image of the central region of the Milky Way Galaxy holds a new radio source, GCRT J1745-3009.
The new radio source is located below the expanding ring of debris of this supernova remnant.
The National Radio Astronomy Observatory (NRAO) is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc. NRAO designs, builds and operates the world’s most sophisticated and advanced radio telescopes.
www.nrao.edu /pr/2005/newsource   (1155 words)

  
 Historical Background (from radio) --  Britannica Student Encyclopedia
The first known radio broadcast in the United States was made by Reginald A. Fessenden from an experimental station in Brant Rock, Mass., on Dec. 24, 1906.
A typical CB radio consists of a combined transmitter-receiver (a transceiver) and an antenna.
radio receiver and directional antenna system used to determine the direction of the source of a signal.
www.britannica.com /ebi/article-207079?ct=   (889 words)

  
 I. I. Pronik: On the Relation of the Position Angles of Elongated Structures and Vector of Polarization of the ...   (Site not responding. Last check: 2007-11-04)
Using literary data the comparison of the position angles (PA) of elongated structures and of the polarization vector E of 2, 4 and 6 cm emission of compact source 3C 84 was carried out.
Parallel direction of polarization vector and curved radio jet of 3C 84 source agree with the model of distribution of magnetic fields and knots of relativistic electrons emission in mildly relativistic ejections of BL Lac objects, considered by Gabuzda et al.
In the case of 3C 84 this model must be complicated because its radio jet changes the direction under the influence of external magnetic field.
www.cv.nrao.edu /~azensus/iau164/iaudir/reg/l2hab/node155.html   (241 words)

  
 Active Galaxies and Quasars - Introduction
and this excess energy is found in the infrared, radio, UV, and X-ray regions of the electromagnetic spectrum.
Radio observations of AGN often show powerful jets, streams of particles coming from the central source -- like water from a spigot.
All these objects appear to emit most of their bolometric luminosity at gamma-ray energies and, in addition, are strong extragalactic radio sources.
imagine.gsfc.nasa.gov /docs/science/know_l1/active_galaxies.html   (1213 words)

  
 The Nobel Prize in Physics 1993 - Presentation Speech
A terrestrial radio receiving antenna aimed at this transmitter picks up a signal that pulsates at the same frequency as the extinguished star rotates.
This pulsating radio signal was the origin of the name "pulsar." During a series of observations employing refined techniques to study the occurrence of pulsars, Joseph Taylor and his doctoral student Russell Hulse made the discovery that is being rewarded with this year's Nobel Prize.
Perhaps a radio astronomer in a distant civilization is sitting right now, recording these pulses and pondering why "his" pulsar is demonstrating certain irregularities in its radio signals.
www.nobel.se /physics/laureates/1993/presentation-speech.html   (871 words)

  
 Radio Source Variability (including Penticton source lists)   (Site not responding. Last check: 2007-11-04)
The variability of radio sources at 151 MHz has been studied in detail using the CLFST, as part of the
From Green and Riley (1995), the 51P and 52P source lists at 408 MHz, plus the 53P and 54P source lists at 1420 MHz.
These source lists each contain (see Green and Riley 1995 for details): 1) the source name; 2) the source right ascension and declination (B1950.0); 3) the peak flux density (/mJy); 4) the integrated flux density (/mJy); 5) the primary beam correction, and 6) the signal/noise ratio of the source.
www.mrao.cam.ac.uk /surveys/varies/index.html   (328 words)

  
 Unveiling the secrets of the radio source 3C120
In order to explain their enormous energy output extragalactic jets must be linked to very energetic astrophysical phenomena, like e.g., the ejection of relativistic plasma from the neighborhood of supermassive fl holes existing in the centers of active galaxies.
From 1997 to 1999 the radio galaxy 3C120 has been the object of a detailed observational campaign by Jose L. Gòmez and co-workers using VLBA, a system of more than ten large radio antennas operated by the US National Radio Astronomy Observatory and scattered across the whole USA from Hawaii to the Virgin Islands.
The observations have revealed the existence of a cloud of gas (about 25 lightyears away from the central fl hole), which is apparently being struck by a jet with a velocity of about 98.6% of the speed of light.
www.mpa-garching.mpg.de /HIGHLIGHT/2001/highlight0101_e.html   (710 words)

  
 IngentaConnect The radio source counts at 15 GHz and their implications for cm-w...   (Site not responding. Last check: 2007-11-04)
We use the preliminary results of a new survey of radio sources made using the Ryle Telescope at 15.2 GHz, to estimate the impact of foreground sources on cm-wave cosmic microwave background (CMB) images.
This is the highest frequency survey that is relevant to the issue of radio source contamination in CMB experiments.
We compare the population of sources observed in this new survey to that predicted by extrapolation from lower frequency surveys, finding that source flux densities, and indeed the existence of many sources, cannot be determined by extrapolation.
www.ingentaconnect.com /content/bsc/mnr/2001/00000327/00000001/art00001   (220 words)

  
 AllRefer.com - quasar (Astronomy, General) - Encyclopedia
Quasars were discovered as the visible counterparts of certain discrete celestial sources of radio waves (see radio astronomy).
Although their visible light is faint, the quasars are optically brighter than the galaxies with which radio sources had been identified before 1963.
Before their spectra were studied carefully, it was believed that the quasars were stars in our galaxy.
reference.allrefer.com /encyclopedia/Q/quasar.html   (385 words)

  
 IngentaConnect Optical identifications and spectroscopy of a faint radio source ...   (Site not responding. Last check: 2007-11-04)
Optical identifications and spectroscopy of a faint radio source sample: the nature of the sub-mJy population
Moreover, using mainly the large radio-to-optical ratio and the information from the available limits on the optical magnitudes of the unidentified radio sources, we conclude that the great majority of them are likely to be early-type galaxies, at z > 1.
If correct, it would suggest that the evolution of the radio luminosity function of spiral galaxies, including starbursts, might not be as strong as suggested in previous evolutionary models.
www.ingentaconnect.com /content/bsc/mnr/1999/00000304/00000001/art02301   (435 words)

  
 Active Galaxies and Quasars - Superluminal Motion in 3C 279   (Site not responding. Last check: 2007-11-04)
The superluminal radio source in the gamma-ray blazar 3C 279
One of the greatest surprises provided by very-long baseline interferometry (VLBI) observations was the fact that some quasars, radio galaxies, and BL Lacertae objects exhibit motion along their jets which works out to several times faster than light.
And the sources with superluminal motion are typically just those most likely to be pointed toward us - they are bright because of Doppler boosting, and there also seems to be a connection between strong gamma-ray emission and superluminal radio structure.
www.astr.ua.edu /keel/agn/3c279.html   (413 words)

  
 A Large Double Radio Source from a Spiral Galaxy: 0313-192
Powerful double radio sources universally arise from elliptical galaxies or merger remnants, which has shaped theories of their origin.
Star formation, radial extent of the dust, and modest bulge/disk ratio all indicate that the galaxy is a genuine spiral, the only one identified to host a giant double radio source.
This is nearly perpendicular to the radio jet axis.
www.astr.ua.edu /keel/research/rg0313.html   (891 words)

  
 Interactions Between the Radio Source and Surrounding Gas at the Center of the Cooling-Flow Cluster Abell 2597   (Site not responding. Last check: 2007-11-04)
We discuss ways in which the radio source is interacting directly with the ambient gas: the radio lobe to the north of the active nucleus is surrounded by a shell of line-emitting gas, while the radio jet to the south appears to be substantially deflected by a dense, cool cloud of gas.
The effect of the surrounding gas upon the evolution of the radio source is discussed, together with the overall role played by the radio source in the long-term energetics of the cooling-flow nebula.
We also present detailed observations of a number of compact regions of blue continuum emission that appear to be indicative of recent star formation, and discuss their likely origin and evolutionary history in the context of the evolution of the radio source.
www.aas.org /publications/baas/v30n2/aas192/abs/S011011.html   (303 words)

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