Bibliografie tematiche / Radio astronomy

Letteratura scientifica selezionata sul tema "Radio astronomy"

Autore: Grafiati
Pubblicato: 4 giugno 2021
Ultima modifica: 6 settembre 2023

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Articoli di riviste sul tema "Radio astronomy"

1

Baldwin, J. E., P. G. Mezger, A. Barrett, A. Baudry, R. Booth, D. Jauncey, V. Kapahi et al. "40. Radio Astronomy (Radio Astronomie)". Transactions of the International Astronomical Union 20, n. 01 (1988): 539–66. http://dx.doi.org/10.1017/s0251107x00007379.

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The following commission members have contributed to this report:M Birkinshaw, R J Cohen, J J Condon, T J Cornwell, J R Dickel, P A Feldman, R Genzel, M Goss, V Kapahl, Gopal Krishna, M Kundu, A G Lyne, C R Masson, A C Readhead, W Reich, J M Riley, A J Turtle, J M van der Hulst, T L Wilson.
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2

Bowler, Sue. "Nigeria's first radio astronomer". Astronomy & Geophysics 61, n. 5 (1 ottobre 2020): 5.28–5.30. http://dx.doi.org/10.1093/astrogeo/ataa072.

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3

Matejka, A. "Radio Astronomy". Minnesota review 2012, n. 78 (1 giugno 2012): 3. http://dx.doi.org/10.1215/00265667-1550437.

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4

Cohen, R. J. "Radio Astronomy and the Radio Regulations". Symposium - International Astronomical Union 196 (2001): 220–28. http://dx.doi.org/10.1017/s0074180900164137.

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This article gives a brief introduction to the status of radio astronomy within the International Telecommunication Union (ITU), the body which coordinates global telecommunications. Radio astronomy entered the ITU arena in 1959 as a relative latecomer. By its nature, radio astronomy does not fit into the ITU system very well: regulators are hoping to facilitate commercial development of the radio spectrum, whereas astronomers are hoping to retain quiet frequency bands through which to study the Universe at ever higher sensitivity. Nevertheless there are major long-term goals which radio astronomers can realistically hope to achieve via the ITU in the years ahead, including more favourable frequency allocations and better regulatory protection. The prospects for radio astronomy at the forthcoming World Radio Conference WRC-2000 are reviewed. It is vital that radio astronomers participate in force at this WRC.
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5

Mitton, Simon. "Book Review: Radio Astronomy Reprints: Classics in Radio Astronomy". Journal for the History of Astronomy 17, n. 3 (agosto 1986): 212. http://dx.doi.org/10.1177/002182868601700315.

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6

Frater, R. H., W. M. Goss e H. W. Wendt. "Bernard Yarnton Mills 1920–2011". Historical Records of Australian Science 24, n. 2 (2013): 294. http://dx.doi.org/10.1071/hr13002.

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Bernie Mills is remembered globally as an influential pioneer in the evolving field of radio astronomy. His contributions with the ‘Mills Cross' at the CSIRO Division of Radiophysics and later at the University of Sydney's School of Physics and the development of the Molonglo Observatory Synthesis Telescope (MOST) were widely recognized as astronomy evolved in the years 1948–85 and radio astronomy changed the viewpoint of the astronomer as a host of new objects were discovered.
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7

Swarup, Govind. "The Journey of a Radio Astronomer: Growth of Radio Astronomy in India". Annual Review of Astronomy and Astrophysics 59, n. 1 (8 settembre 2021): 1–19. http://dx.doi.org/10.1146/annurev-astro-090120-014030.

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In this autobiographical account, I first describe my family, then childhood and education in India. During 1953–55, I worked in the new field of radio astronomy at the Division of Radiophysics of the Commonwealth Scientific and Industrial Research Organisation in Australia. During 1956–57, I worked at the Radio Astronomy Station of Harvard University at Fort Davis, Texas, where I made observations of solar radio bursts at decimeter wavelengths. I then joined Stanford University as a graduate student in 1957. I contributed to the successful operation of the Stanford Cross Antenna and then used it for studying microwave radio emission from the Sun. I was awarded the Ph.D. degree by Stanford University in 1960 and was then appointed as an Assistant Professor for three years. With an urge to contribute to evolving scientific endeavors in India, I joined the Tata Institute of Fundamental Research (TIFR) at Mumbai, India, in April 1963. In my stay of more than three decades at TIFR, I conceived of, and guided, construction of two of the world's largest radio telescopes, namely the Ooty Radio Telescope and the Giant Metrewave Radio Telescope. These instruments have led to several outstanding contributions and discoveries in the areas of radio galaxies, quasars, pulsars, and cosmology.
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8

Kellermann, K. I., J. Baldwin, J. G. Abies, N. Broten, G. Dulk, B. Hoglund, N. Kardashev et al. "40. Radio Astronomy". Transactions of the International Astronomical Union 19, n. 1 (1985): 549–80. http://dx.doi.org/10.1017/s0251107x00006623.

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The last triennium marked the 50th anniversary of the paper describing the first observations of cosmic radio emission by Karl Jansky in 1933. Sullivan (82 Classics in Radio Astronomy, Reidel) has published a collection of the major historical papers in radio astronomy, and collections of papers discussing the historical development have been published by Sullivan (84 Early Years of Radio Astronomy, Cambridge Univ. Press) and by Kellermann and Sheets (84 Serendipitous Discoveries in Radio Astronomy, NRAO).
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9

Frater, R. H., W. M. Goss e H. W. Wendt. "Bernard Yarnton Mills AC FAA. 8 August 1920 — 25 April 2011". Biographical Memoirs of Fellows of the Royal Society 59 (gennaio 2013): 215–39. http://dx.doi.org/10.1098/rsbm.2013.0015.

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Abstract (sommario):
Bernie Mills is remembered globally as an influential pioneer in the evolving field of radio astronomy. His contributions with the ‘Mills Cross’ at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Division of Radiophysics and later at the University of Sydney’s School of Physics and the development of the Molonglo Observatory Synthesis Telescope (MOST) were widely recognized as astronomy evolved in the years 1948–85 and radio astronomy changed the viewpoint of the astronomer as a host of new objects were discovered.
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10

Afraimovich, É. L., G. Ya Smol’kov e Yu V. Yasyukevich. "Adaptive radio astronomy". Doklady Physics 53, n. 4 (aprile 2008): 211–15. http://dx.doi.org/10.1134/s1028335808040095.

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Tesi sul tema "Radio astronomy"

1

Van, Tonder Vereese. "Beamforming for radio astronomy". Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/96126.

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Thesis (MEng) -- Stellenbosch University, 2014.
ENGLISH ABSTRACT: Beamforming is a technique used to combine signals from an array of antennas to effectively synthesize a single aperture and beam. In the Radio Astronomy community the technique is used to obtain a desirable beam pattern as well as to electronically point the beam of an array. Next generation radio telescopes such as the Square Kilometre Array (SKA) surpass current technology and will extensively make use of beamforming techniques. Various factors determine the output of a beamformer; however, given an array with a fixed configuration only the weights applied to the incoming signals affect the synthesized aperture and beam. Furthermore, the incoming data must be processed in real-time, at a rate equal to the input-output rate of the processor. Both the weighting function and the real-time implementation of beamforming, are the primary subjects of this thesis. In this thesis various deterministic weighting functions are investigated. The algorithms are implemented in a matlab program, serving as a simulation tool for investigating the techniques. The program is verified by comparing the expected theoretical outcomes to the simulated output. For the program the following functionalities are included: a steering technique, spectral weighting, Dolph-Chebychev, and the Least Square Error algorithm. Applications of these techniques is investigated and their prominence in the Radio Astronomy community is established. For the real-time beamformer implementation, the UniBoard platform configured with beamformer firmware, is investigated. This is important as the UniBoard is an excellent example of a beamformer implementation within the Radio Astronomy community. The architecture is used to emulate a linear array by implementing a python control script, where the output corresponded accurately with the expected theoretical values. The thesis also constitutes the design and implementation of a digital frequency domain beamformer on the ROACH board. This processing board is employed by the Karoo Array Telescope (KAT-7) in South Africa. This work is therefore important as it demonstrates a beamformer implementation on an architecture in use by the Radio Astronomy community. An antenna array is designed and built for the verification of the beamformer design. Results with a good degree of accuracy were obtained and where errors exist they are discussed.
AFRIKKANSE OPSOMMING: Bundelvorming is ’n tegniek waarmee die seine van ’n antenna samestelling gekombineer word om ’n enkele effektiewe stralingsvlak en stralingspatroon te sintiseer. In die Radio Astronomie gemeenskap word die tegniek gebruik om ’n gewenste stralingspatroon te sintiseer sowel as om die rigting van die patroon elektronies te beheer. Die Square Kilometre Array (SKA) is ’n toekomstige radioteleskoop en sal grootliks gebruik maak van bundelvorming tegnieke. Die uitset van bundelvormers word geaffekteer deur verskeie faktore, maar vir ’n gegewe samestelling is dit net die gewigsfunksies wat toegepas word op die inkomende seine wat die gesintiseerde patroon kan beheer. Verder moet die inkomende data verwerk word teen ’n tempo gelykstaande aan die inset-en-uitsetkoers van die verwerker. Die gewigsfunksie so wel as die implementasie van die bundelvormer is albei primêre onderwerpe van die tesis. ’n Verskeindenheid van deterministiese bundelvormingstegnieke sal ondersoek word in hierdie tesis. Die algoritmes is in ’n matlab program geïmplementeer vir simulasie doeleindes. Die program is geverifieër deur die uitset te vergelyk met die verwagte teoretiese waardes. Die program sluit die volgende funksies in: ’n rigting beheer algoritme, spektraalgewigte, Dolph-Chebychev, en die minste vierkantsfout algoritme. Hierdie tegnieke is van belang weens hul toepassing in die Radio Astronomie gemeenskap. Vir die implementasie van ’n bundelvormer is die UniBoard hardeware, geprogrameer in ’n bundelvormings modus, van gebruik gemaak. Hierdie aspek is belangrik omdat die Uni- Board ’n goeie voorbeeld van ’n geïmplementeerde bundelvormer in die Radio Astronomie gemeenskap is. Die UniBoard word gebruik om ’n lineêre samestelling te emuleer deur in python ’n beheer skrip te skryf, waar die uitset van die emuleerder akkuraat ooreenstem met die verwagte waardes. Die tesis behels ook die ontwerp en implementasie van ’n digitale frekwensiegebied bundelvormer op die ROACH platform. Hierdie verwerker word tans gebruik in die Karoo Array Telescope (KAT-7) in Suid-Afrika. Hierdie werk is dus belangrik omdat dit die implementasie van ’n bundelvormer op tegnologie wat huidiglik in die Radio Astronomie gemeenskap gebruik word demonstreer. Daarbenewens is ’n antenna samestelling ontwerp en gebou om die bundelvormer te verifieër. Die resultate is akkuraat tot ’n redelike mate. Waar daar ’n fout onstaan het word dit in die tesis bespreek.
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2

Junklewitz, Henrik. "Statistical inference in radio astronomy". Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-177457.

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This thesis unifies several studies, which all are dedicated to the subject of statistical data analysis in radio astronomy and radio astrophysics. Radio astronomy, like astronomy as a whole, has undergone a remarkable development in the past twenty years in introducing new instruments and technologies. New telescopes like the upgraded VLA, LOFAR, or the SKA and its pathfinder missions offer unprecedented sensitivities, previously uncharted frequency domains and unmatched survey capabilities. Many of these have the potential to significantly advance the science of radio astrophysics and cosmology on all scales, from solar and stellar physics, Galactic astrophysics and cosmic magnetic fields, to Galaxy cluster astrophysics and signals from the epoch of reionization. Since then, radio data analysis, calibration and imaging techniques have entered a similar phase of new development to push the boundaries and adapt the field to the new instruments and scientific opportunities. This thesis contributes to these greater developments in two specific subjects, radio interferometric imaging and cosmic magnetic field statistics. Throughout this study, different data analysis techniques are presented and employed in various settings, but all can be summarized under the broad term of statistical infer- ence. This subject encompasses a huge variety of statistical techniques, developed to solve problems in which deductions have to be made from incomplete knowledge, data or measurements. This study focuses especially on Bayesian inference methods that make use of a subjective definition of probabilities, allowing for the expression of probabilities and statistical knowledge prior to an actual measurement. The thesis contains two different sets of application for such techniques. First, situations where a complicated, and generally ill-posed measurement problem can be approached by assuming a statistical signal model prior to infer the desired measured variable. Such a problem very often is met should the measurement device take less data then needed to constrain all degrees of freedom of the problem. The principal case investigated in this thesis is the measurement problem of a radio interferometer, which takes incomplete samples of the Fourier transformed intensity of the radio emission in the sky, such that it is impossible to exactly recover the signal. The new imaging algorithm RESOLVE is presented, optimal for extended radio sources. A first showcase demonstrates the performance of the new technique on real data. Further, a new Bayesian approach to multi-frequency radio interferometric imaging is presented and integrated into RESOLVE. The second field of application are astrophysical problems, in which the inherent stochas- tic nature of a physical process demands a description, where properties of physical quanti- ties can only be statistically estimated. Astrophysical plasmas for instance are very often in a turbulent state, and thus governed by statistical hydrodynamical laws. Two studies are presented that show how properties of turbulent plasma magnetic fields can be inferred from radio observations.
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3

Thompson, Nicholas Christopher. "RFI mitigation in radio astronomy". Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86637.

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Thesis (MEng)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Technical advances in electromagnetics, signal processing and processing power have led to a significant increase in sensitivity and accuracy in radio telescopes. With this increase in sensitivity, radio frequency interference (RFI) has become a much larger problem. The notable growth in wireless communication as well as self generated RFI has further escalated this problem. In order to utilise the full capabilities of modern radio telescopes, RFI mitigation is required on the captured signals. With the enormous data rates of modern radio telescopes, managing RFI has become increasingly difficult, and in order to utilise the full captured radio spectrum, more accurate RFI mitigation strategies will be necessary. The use of different RFI mitigation strategies is studied in the form of online and offline techniques. This includes Spectral Kurtosis, Spectral Flatness and the Var/SumThreshold method. The special case for RFI mitigation in timing pulsars will also be studied. These techniques are well known in the radio astronomy community; here, spectral kurtosis and spectral flatness will be implemented on the raw data as well as the post correlated data. System speed and accuracy will be the deciding factors when testing these methods as possible solutions to this problem.
AFRIKAANSE OPSOMMING: ‘n Toename in die sensitiwiteit van hedendagse radioteleskope kan toegedra word aan die tegniese bevordering in elktromagnetika en seinverwerking. Die toename in sensitiwiteit het egter tot die gevolg dat radiofrekwensiesteuring ‘n groter rol speel in hedendaagse radioteleskope. Die groei in die gebruik van radioverbindings asook die gevolge van self gei¨nduseerde radiofrekwensiesteuring dra ook verder by tot hierdie probleem. Radiofrekwensiesteuring matiging word toegepas op die opgevangde seine, om sodoende gebruik te maak van die volle kapasiteit van moderne radioteleskope. Die bestuur van radiofrekwensiesteuring word bemoeilik deur die groot hoeveelheid intydse data van die radioteleskope. Meer akurate radiofrekwensiesteuring matigingstegnieke word vereis om die bandwydte ten volle te hanteer. Daar word op ‘n aantal verskillende matingstegnieke gefokus. Hierdie tegenieke kan in twee kategorieë verdeel word, naamlik aanlyn- en aflyntegenieke. Onderafdelings van hierdie kategorieë sluit in: spektrale kurtose, spektrale matheid en “Var/SumThreshold”. Daar word ook na ‘n spesiale geval van radiofrekwensiesteuring matiging gekyk, in die opmeeting van tydsberekening-pulsars. Alhoewel hierdie tegnieke bekend is in die radioastronomie gemeenskap, word spektrale kurtose en spektrale matheid egter toegepas op die rou data sowel as postgekorreleerde data. Daar sal op stelsel spoed en akuratheid gefokus word, om vas te stel of hierdie metodes wel moontlike oplossings bied tot die probleem bespreek.
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4

Mitchell, Daniel Allan. "Interference Mitigation in Radio Astronomy". Thesis, The University of Sydney, 2004. http://hdl.handle.net/2123/693.

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This thesis investigates techniques and algorithms for mitigating radio frequency interference (RFI) affecting radio astronomy observations. In the past radio astronomy has generally been performed in radio-quiet geographical locations and unused parts of the radio spectrum, including small protected frequency bands. The increasing use of the entire spectrum and global transmitters such as satellites are forcing the astronomy community to begin implementing active interference cancelling. The amount of harmful interference affecting observations will also increase as future instruments such as the Square Kilometre Array (SKA) are required to use larger bandwidths to reach up to 100 times the current sensitivity levels, and as spectral line observations require observing in bands licensed to other spectrum users. Particular attention is paid to interference cancellation algorithms which make use of reference beams. This has proven to be successful in removing interference from the contaminated astronomical data. Reference antenna cancellers are closely analysed, leading to filters and techniques that can offer improved RFI excision for some important applications. It is shown that pre- and post-correlation reference antenna cancellers give similar results, and an important aspect of the cancellers is the use of a second reference signal when the reference interference-to-noise ratio is low. These modified filters can theoretically offer infinite interference suppression in the voltage domain, equivalent to that of post-correlation interference cancellers, and their internal structure can offer an understanding of the residual RFI and added receiver noise components of a variety of reference antenna techniques. The effect of variable geometric delays is also considered and various filters are compared as a function of the geometric fringe rate.
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5

Mitchell, Daniel Allan. "Interference Mitigation in Radio Astronomy". University of Sydney. Physics, 2004. http://hdl.handle.net/2123/693.

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Abstract (sommario):
This thesis investigates techniques and algorithms for mitigating radio frequency interference (RFI) affecting radio astronomy observations. In the past radio astronomy has generally been performed in radio-quiet geographical locations and unused parts of the radio spectrum, including small protected frequency bands. The increasing use of the entire spectrum and global transmitters such as satellites are forcing the astronomy community to begin implementing active interference cancelling. The amount of harmful interference affecting observations will also increase as future instruments such as the Square Kilometre Array (SKA) are required to use larger bandwidths to reach up to 100 times the current sensitivity levels, and as spectral line observations require observing in bands licensed to other spectrum users. Particular attention is paid to interference cancellation algorithms which make use of reference beams. This has proven to be successful in removing interference from the contaminated astronomical data. Reference antenna cancellers are closely analysed, leading to filters and techniques that can offer improved RFI excision for some important applications. It is shown that pre- and post-correlation reference antenna cancellers give similar results, and an important aspect of the cancellers is the use of a second reference signal when the reference interference-to-noise ratio is low. These modified filters can theoretically offer infinite interference suppression in the voltage domain, equivalent to that of post-correlation interference cancellers, and their internal structure can offer an understanding of the residual RFI and added receiver noise components of a variety of reference antenna techniques. The effect of variable geometric delays is also considered and various filters are compared as a function of the geometric fringe rate.
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6

Bock, Douglas Carl-Johan. "Wide Field Aperture Synthesis Radio Astronomy". University of Sydney. Physics, 1998. http://hdl.handle.net/2123/377.

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This thesis is focussed on the Molonglo Observatory Synthesis Telescope (MOST), reporting on two primary areas of investigation. Firstly, it describes the recent upgrade of the MOST to perform an imaging survey of the southern sky. Secondly, it presents a MOST survey of the Vela supernova remnant and follow-up multiwavelength studies. The MOST Wide Field upgrade is the most significant instrumental upgrade of the telescope since observations began in 1981. It has made possible the nightly observation of fields with area ~5 square degrees, while retaining the operating frequency of 843 MHz and the pre-existing sensitivity to point sources and extended structure. The MOST will now be used to make a sensitive (rms approximately 1 mJy/beam) imaging survey of the sky south of declination -30°. This survey consists of two components: an extragalactic survey, which will begin in the south polar region, and a Galactic survey of latitudes |b| < 10°. These are expected to take about ten years. The upgrade has necessitated the installation of 352 new preamplifiers and phasing circuits which are controlled by 88 distributed microcontrollers, networked using optic fibre. The thesis documents the upgrade and describes the new systems, including associated testing, installation and commissioning. The thesis continues by presenting a new high-resolution radio continuum survey of the Vela supernova remnant (SNR), made with the MOST before the completion of the Wide Field upgrade. This remnant is the closest and one of the brightest SNRs. The contrast between the structures in the central pulsar-powered nebula and the synchrotron radiation shell allows the remnant to be identified morphologically as a member of the composite class. The data are the first of a composite remnant at spatial scales comparable with those available for the Cygnus Loop and the Crab Nebula, and make possible a comparison of radio, optical and soft X-ray emission from the resolved shell filaments. The survey covers an area of 50 square degrees at a resolution of 43" x 60", while imaging structures on scales up to 30'. It has been used for comparison with Wide Field observations to evaluate the performance of the upgraded MOST. The central plerion of the Vela SNR (Vela X) contains a network of complex filamentary structures. The validity of the imaging of these filaments has been confirmed with Very Large Array (VLA) observations at 1.4 GHz. Unlike the situation in the Crab Nebula, the filaments are not well correlated with H-alpha emission. Within a few parsec of the Vela pulsar the emission is much more complex than previously seen: both very sharp edges and more diffuse emission are present. It has been postulated that one of the brightest filaments in Vela X is associated with the X-ray feature (called a `jet') which appears to be emanating from the region of the pulsar. However, an analysis of the MOST and VLA data shows that this radio filament has a flat spectral index similar to another more distant filament within the plerion, indicating that it is probably unrelated to the X-ray feature.
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7

Ngongoni, Chipo Nancy. "Neural cross-correlation for radio astronomy". Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/11427.

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Includes abstract.
Includes bibliographical references (leaves 56-62).
Correlation engines are essential elements of most signal processing systems. Areas of applicability include image processing, speech synthesis and analysis, high energy physics, wireless and mobile communication systems, spread spectrum communication systems and even prosthetics. Finding cost effective and computationally less intensive engines is the thrust of most research. Neural networks have also been used as aids in making complex tasks relatively easy to process.
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8

Manley, Jason Ryan. "A scalable packetised radio astronomy imager". Doctoral thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/15573.

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Includes bibliographical references
Modern radio astronomy telescopes the world over require digital back-ends. The complexity of these systems depends on many site-specific factors, including the number of antennas, beams and frequency channels and the bandwidth to be processed. With the increasing popularity for ever larger interferometric arrays, the processing requirements for these back-ends have increased significantly. While the techniques for building these back-ends are well understood, every installation typically still takes many years to develop as the instruments use highly specialised, custom hardware in order to cope with the demanding engineering requirements. Modern technology has enabled reprogrammable FPGA-based processing boards, together with packet-based switching techniques, to perform all the digital signal processing requirements of a modern radio telescope array. The various instruments used by radio telescopes are functionally very different, but the component operations remain remarkably similar and many share core functionalities. Generic processing platforms are thus able to share signal processing libraries and can acquire different personalities to perform different functions simply by reprogramming them and rerouting the data appropriately. Furthermore, Ethernet-based packet-switched networks are highly flexible and scalable, enabling the same instrument design to be scaled to larger installations simply by adding additional processing nodes and larger network switches. The ability of a packetised network to transfer data to arbitrary processing nodes, along with these nodes' reconfigurability, allows for unrestrained partitioning of designs and resource allocation. This thesis describes the design and construction of the first working radio astronomy imaging instrument hosted on Ethernet-interconnected re- programmable FPGA hardware. I attempt to establish an optimal packetised architecture for the most popular instruments with particular attention to the core array functions of correlation and beamforming. Emphasis is placed on requirements for South Africa's MeerKAT array. A demonstration system is constructed and deployed on the KAT-7 array, MeerKAT's prototype. This research promises reduced instrument development time, lower costs, improved reliability and closer collaboration between telescope design teams.
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9

Bock, Douglas Carl-Johan. "Wide Field Aperture Synthesis Radio Astronomy". Thesis, The University of Sydney, 1997. http://hdl.handle.net/2123/377.

Testo completo
Abstract (sommario):
This thesis is focussed on the Molonglo Observatory Synthesis Telescope (MOST), reporting on two primary areas of investigation. Firstly, it describes the recent upgrade of the MOST to perform an imaging survey of the southern sky. Secondly, it presents a MOST survey of the Vela supernova remnant and follow-up multiwavelength studies. The MOST Wide Field upgrade is the most significant instrumental upgrade of the telescope since observations began in 1981. It has made possible the nightly observation of fields with area ~5 square degrees, while retaining the operating frequency of 843 MHz and the pre-existing sensitivity to point sources and extended structure. The MOST will now be used to make a sensitive (rms approximately 1 mJy/beam) imaging survey of the sky south of declination -30°. This survey consists of two components: an extragalactic survey, which will begin in the south polar region, and a Galactic survey of latitudes |b| < 10°. These are expected to take about ten years. The upgrade has necessitated the installation of 352 new preamplifiers and phasing circuits which are controlled by 88 distributed microcontrollers, networked using optic fibre. The thesis documents the upgrade and describes the new systems, including associated testing, installation and commissioning. The thesis continues by presenting a new high-resolution radio continuum survey of the Vela supernova remnant (SNR), made with the MOST before the completion of the Wide Field upgrade. This remnant is the closest and one of the brightest SNRs. The contrast between the structures in the central pulsar-powered nebula and the synchrotron radiation shell allows the remnant to be identified morphologically as a member of the composite class. The data are the first of a composite remnant at spatial scales comparable with those available for the Cygnus Loop and the Crab Nebula, and make possible a comparison of radio, optical and soft X-ray emission from the resolved shell filaments. The survey covers an area of 50 square degrees at a resolution of 43" x 60", while imaging structures on scales up to 30'. It has been used for comparison with Wide Field observations to evaluate the performance of the upgraded MOST. The central plerion of the Vela SNR (Vela X) contains a network of complex filamentary structures. The validity of the imaging of these filaments has been confirmed with Very Large Array (VLA) observations at 1.4 GHz. Unlike the situation in the Crab Nebula, the filaments are not well correlated with H-alpha emission. Within a few parsec of the Vela pulsar the emission is much more complex than previously seen: both very sharp edges and more diffuse emission are present. It has been postulated that one of the brightest filaments in Vela X is associated with the X-ray feature (called a `jet') which appears to be emanating from the region of the pulsar. However, an analysis of the MOST and VLA data shows that this radio filament has a flat spectral index similar to another more distant filament within the plerion, indicating that it is probably unrelated to the X-ray feature.
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10

Carozzi, Tobia. "Radio waves in the ionosphere : Propagation, generation and detection". Doctoral thesis, Uppsala universitet, Institutionen för astronomi och rymdfysik, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-1184.

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We discuss various topics concerning the propagation, generation, and detec-tionof high-frequency (HF) radio waves in the Earth's ionosphere. With re-gardsto propagation, we derive a full wave Hamiltonian and a polarization evo-lutionequation for electromagnetic waves in a cold, stratified magnetoplasma.With regards to generation, we will be concerned with three experiments con-ducted at the ionosphere- radio wave interaction research facilities at Sura, Rus-siaand Tromsø, Norway. These facilities operate high power HF transmittersthat can inject large amplitude electromagnetic waves into the ionosphere andexcite numerous nonlinear processes. In an experiment conducted at the Surafacility, we were able to measure the full state of polarization of stimulatedelectromagnetic emissions for the first time. It is expected that by using thetechnique developed in this experiment it will be possible to study nonlinearpolarization effects on powerful HF pump waves in magnetoplasmas in the fu-ture.In another experiment conducted at the Sura facility, the pump frequencywas swept automatically allowing rapid, high-resolution measurements of SEEdependence on pump frequency with minimal variations in ionospheric condi-tions.At the Tromsø facility we discovered by chance a highly variable, pumpinduced, HF emission that most probably emanated from pump excited spo-radicE. Regarding detection, we have proposed a set of Stokes parametersgeneralized to three dimension space; and we have used these parameters in aninvention to detect the incoming direction of electromagnetic waves of multiplefrequencies from a single point measurement.
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Libri sul tema "Radio astronomy"

1

Lauterbach, Thomas. Radio Astronomy. Wiesbaden: Springer Fachmedien Wiesbaden, 2022. http://dx.doi.org/10.1007/978-3-658-36035-1.

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2

Nourse, Alan Edward. Radio Astronomy. New York: F. Watts, 1989.

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3

Radio astronomy. 2a ed. Powell, Ohio: Cygnus-Quasar, 1986.

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4

Radio astronomy. Mankato, Minn: Smart Apple Media, 2000.

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5

Kraus, John Daniel. Radio astronomy. A cura di Tiuri Martti 1925-, Räisänen Antti V e Carr Thomas D. 2a ed. Powell, Ohio (P.O. Box 85, Powell 43065): Cygnus-Quasar Books, 1986.

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Sofue, Yoshiaki. Galactic Radio Astronomy. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-3445-9.

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7

National Research Council (U.S.). Committee on Radio Frequencies., a cura di. Radio astronomy observatories. Washington, D.C: National Academy Press, 1989.

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8

Leeuwen, Joeri van. Radio pulsars. [S.l: s.n.], 2004.

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1942-, Wilson T. L., a cura di. Tools of radio astronomy. 4a ed. Berlin: Springer, 2004.

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10

Tools of radio astronomy. Berlin: Springer-Verlag, 1986.

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Capitoli di libri sul tema "Radio astronomy"

1

McNally, Derek. "Radio Astronomy (Radio Astronomie)". In Reports on Astronomy, 449–75. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3364-7_28.

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Baldwin, J. E., P. G. Mezger, A. Barrett, A. Baudry, R. Booth, D. Jauncey, V. Kapahi et al. "Radio Astronomy". In Reports on Astronomy, 539–66. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-2981-4_30.

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Zarka, Philippe. "Radio Astronomy". In Encyclopedia of Astrobiology, 1413–19. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-11274-4_1339.

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McGillivray, Donald. "Radio Astronomy". In Physics and Astronomy, 149–64. London: Macmillan Education UK, 1987. http://dx.doi.org/10.1007/978-1-349-09123-2_10.

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Gallaway, Mark. "Radio Astronomy". In Undergraduate Lecture Notes in Physics, 171–82. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-23377-2_14.

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Zarka, Philippe. "Radio Astronomy". In Encyclopedia of Astrobiology, 2124–31. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-44185-5_1339.

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Bergeron, Jacqueline. "Radio Astronomy". In Reports on Astronomy, 447–59. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-1100-3_30.

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West, Richard M. "Radio Astronomy". In Reports on Astronomy, 549–80. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-5392-5_30.

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Leverington, David. "Radio Astronomy". In A History of Astronomy, 310–19. London: Springer London, 1995. http://dx.doi.org/10.1007/978-1-4471-2124-4_15.

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Weik, Martin H. "radio astronomy". In Computer Science and Communications Dictionary, 1400. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/1-4020-0613-6_15354.

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Atti di convegni sul tema "Radio astronomy"

1

Ulvestad, James S. "Space radio astronomy". In AIP Conference Proceedings Volume 387. ASCE, 1997. http://dx.doi.org/10.1063/1.52019.

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Silva, Adriana V. R. "Solar Radio Astronomy". In MAGNETIC FIELDS IN THE UNIVERSE: From Laboratory and Stars to Primordial Structures. AIP, 2005. http://dx.doi.org/10.1063/1.2077174.

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Heald, George, e Paolo Serra. "Panoramic Radio Astronomy". In Panoramic Radio Astronomy: Wide-field 1-2 GHz research on galaxy evolution. Trieste, Italy: Sissa Medialab, 2010. http://dx.doi.org/10.22323/1.089.0001.

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Ananthakrishnan, S. "Antennas for Radio Astronomy". In 2009 Applied Electromagnetics Conference (AEMC 2009). IEEE, 2009. http://dx.doi.org/10.1109/aemc.2009.5430592.

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Virkler, Kristen, Melissa Soriano, Jorge L. Pineda, Jonathon Kocz, Shinji Horiuchi, Tyrone McNichols e Brian Bradford. "DSN Radio Astronomy Spectrometer". In 2021 XXXIVth General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS). IEEE, 2021. http://dx.doi.org/10.23919/ursigass51995.2021.9560581.

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van Ardenne, Arnold, Carole Ann Jackson, Dion Kant e Parbhu Patel. "Radio Astronomy and Innovation". In Westerbork Telescope 50th Anniversary. Trieste, Italy: Sissa Medialab, 2019. http://dx.doi.org/10.22323/1.361.0017.

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Scholten, Olaf, Jose Bacelar, Stijn Buitink, Heino Falcke, Hans van der Marel, Hans van der Marel, Roland Klees et al. "Observations outside Radio Astronomy". In Westerbork Telescope 50th Anniversary. Trieste, Italy: Sissa Medialab, 2019. http://dx.doi.org/10.22323/1.361.0018.

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Winberg, Simon. "SwaMURAy - Swapping memory unit for radio astronomy". In 2015 IEEE Radio and Antenna Days of the Indian Ocean (RADIO). IEEE, 2015. http://dx.doi.org/10.1109/radio.2015.7323420.

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Ananthakrishnan, S. "Radio communication, radio astronomy and space science". In 2012 International Conference on Computers and Devices for Communication (CODEC). IEEE, 2012. http://dx.doi.org/10.1109/codec.2012.6509185.

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Sutinjo, Adrian. "Low-frequency radio astronomy engineering in Western Australia". In 2017 IEEE Radio and Antenna Days of the Indian Ocean (RADIO). IEEE, 2017. http://dx.doi.org/10.23919/radio.2017.8242257.

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Rapporti di organizzazioni sul tema "Radio astronomy"

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Kassim, Namir E., T. J. Lazio e William C. Erickson. Opening a New Window on the Universe: High-Resolution, Long-Wavelength Radio Astronomy. Fort Belvoir, VA: Defense Technical Information Center, novembre 2002. http://dx.doi.org/10.21236/ada408473.

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Eshbaugh, J. V. Interface Control Document Between the Radio Astronomy Pointing Computer (PC) and the HUSIR Antenna Control Unit (ACU). Fort Belvoir, VA: Defense Technical Information Center, dicembre 2010. http://dx.doi.org/10.21236/ada533347.

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Francesco, Petruccione,, Gastrow, Michael, Hadzic, Senka, Limpitlaw, Justine, Paul, Babu Sena, Wolhuter, Riaan e Kies, Carl. Evaluation of Alternative Telecommunication Technologies for the Karoo Central Astronomy Advantage Area. Academy of Science of South Africa (ASSAf), 2021. http://dx.doi.org/10.17159/assaf.2021/0073.

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The National Research Foundation (NRF) requested the Academy of Science of South Africa (ASSAf), on behalf of South African Radio Astronomy Observatory (SARAO) and the Square Kilometre Array (SKA), to undertake an independent and objective evaluation of potential alternative telecommunication technologies for the areas of the Karoo Central Astronomy Advantage Areas (KCAAA). The study encompasses regulatory, public sphere, and technical dimensions to explore options for maintaining the functionality of the telescope while, at the same time, delivering appropriate connectivity solutions for local communities.The objectives of this study are as follows: 1) Assess the technologies currently being, or planning to be, deployed through existing alternative communications programs managed by SARAO, including whether these technologies are comparable with market available technologies that could feasibly be deployed in the KCAAA; and 2) Assessment of current and future telecommunication technologies that may act as suitable replacement and/or improvement (functional and feasible) for existing detrimental technologies, utilised in the KCAAA. This report provides a critical background into the relationship between the SKA and local communities as it relates to ICTs in the area. Based on this understanding, potential technology solutions are proposed to ensure residents of the KCAAA are still afforded valuable access to information and communication technologies (ICTs) within the parameters of affordability, desirability and feasibility.
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