Radio astronomy is far from being beyond the scope of amateurs astronomers, and this practical, self-contained guide for the newcomer to practical radio astronomey is an ideal introduction. This guide is a must for anyone who wants to join the growing ranks of 21st Century backyard radio astronomers. The first part of the book provides background material and explains (in a non-mathematical way) our present knowledge of the stronger radio sources – those observable by amateurs – including the Sun, Jupiter, Meteors, Galactic and extra-galactic sources. The second part of the book deals not only with observing, but – assuming no prior technical knowledge of electronics or radio theory – takes the reader step-by-step through the process of building and using a backyard radio telescope. There are complete, detailed plans and construction information for a number of amateur radio telescopes, the simplest of which can be put together and working – using only simple tools – in a weekend. For other instruments, there are full details of circuit-board layouts, components to use and (vitally important in radio astronomy) how to construct antennae for radio astronomy.
The high time-resolution radio sky represents unexplored astronomical territory. This thesis presents a study of the transient radio sky, focussing on millisecond scales. As such, the work is concerned primarily with neutron stars. In particular this research concentrates on a recently identified group of neutron stars, known as RRATs, which exhibit radio bursts every few minutes to every few hours. After analysing neutron star birthrates, a re-analysis of the Parkes Multibeam Pulsar Survey is described which has resulted in the discovery of 19 new transient radio sources. Of these, 12 have been seen to repeat and a follow-up campaign of observations has been undertaken. These studies have greatly increased our knowledge of the rotational properties of RRATs and enable us to conclude that they are pulsars with extreme nulling and/or pulse-to-pulse modulation. Although the evolution of neutron stars post-supernova is not yet understood, it seems that RRATs fit into the emerging picture in which pulsar magnetospheres switch between stable configurations.
Radio astronomy is a mystery to the majority of amateur astronomers, yet it is the best subject to turn to when desirous of an expanded knowledge of the sky. This guide intends to instruct complete newcomers to radio astronomy, and provides help for the first steps on the road towards the study of this fascinating subject. In addition to a history of the science behind the pursuit, directions are included for four easy-to-build projects, based around long-term NASA and Stanford Solar Center projects. The first three projects constitute self-contained units available as kits, so there is no need to hunt around for parts. The fourth – more advanced – project encourages readers to do their own research and track down items. Getting Started in Radio Astronomy provides an overall introduction to listening in on the radio spectrum. With details of equipment that really works, a list of suppliers, lists of online help forums, and written by someone who has actually built and operated the tools described, this book contains everything the newcomer to radio astronomy needs to get going.
Radio techniques were the nrst to lead astronomy away from the quiescent and limited Universe revealed by traditional observations at optical wave lengths. In the earliest days of radio astronomy, a handful of radio physicists and engineers made one startling discovery after another as they opened up the radio sky. With this collection of classic papers and the extensive intro ductory material, the reader can experience these exciting discoveries, as well as understand the developing techniques and follow the motivations which prompted the various lines of inquiry. For instance he or she will follow in detail the several attempts to detect radio waves from the sun at the turn of the century; the unravelling by Jansky of a "steady hiss type static"; the incredible story of Reber who built a 9 meter dish in his backyard in 1937 and then mapped the Milky Way; the vital discoveries by Hey and colleagues of radio bursts from the Sun and of a discrete source in the constellation of Cygnus; the development of receivers and interferometry in the post-war years by the groups led by Ryle in Cambridge and Pawsey in Sydney; the nrst measurements and exciting identiftcations of Taurus A (the Crab Nebula), Centaurus A, Virgo A, Cassiopeia A, and Cygnus A, the last opening the neld of radio cosmology; the early development of synchroton theory; and the prediction and discovery seven years later of the 21 cm line of neutral hy drogen.
This open access book on the history of the National Radio Astronomy Observatory covers the scientific discoveries and technical innovations of late 20th century radio astronomy with particular attention to the people and institutions involved. The authors have made extensive use of the NRAO Archives, which contain an unparalleled collection of documents pertaining to the history of radio astronomy, including the institutional records of NRAO as well as the personal papers of many of the pioneers of U.S. radio astronomy. Technical details and extensive citations to original sources are given in notes for the more technical readers, but are not required for an understanding of the body of the book. This book is intended for an audience ranging from interested lay readers to professional researchers studying the scientific, technical, political, and cultural development of a new science, and how it changed the course of 20th century astronomy.
How radio astronomers challenged national borders, disciplinary boundaries, and the constraints of vision to create an international scientific community. For more than three thousand years, the science of astronomy depended on visible light. In just the last sixty years, radio technology has fundamentally altered how astronomers see the universe. Combining the wartime innovation of radar and the established standards of traditional optical telescopes, the “radio telescope” offered humanity a new vision of the universe. In A Single Sky, the historian David Munns explains how the idea of the radio telescope emerged from a new scientific community uniting the power of radio with the international aspirations of the discipline of astronomy. The radio astronomers challenged Cold War era rivalries by forging a united scientific community looking at a single sky. Munns tells the interconnecting stories of Australian, British, Dutch, and American radio astronomers, all seeking to learn how to see the universe by means of radio. Jointly, this international array of radio astronomers built a new “community” style of science opposing the “glamour” of nuclear physics. A Single Sky describes a communitarian style of science, a culture of interdisciplinary and international integration and cooperation, and counters the notion that recent science has been driven by competition. Collaboration, or what a prominent radio astronomer called “a blending of radio invention and astronomical insight,” produced a science as revolutionary as Galileo's first observations with a telescope. Working together, the community of radio astronomers revealed the structure of the galaxy.
The ideal text for a one-semester course in radio astronomy Essential Radio Astronomy is the only textbook on the subject specifically designed for a one-semester introductory course for advanced undergraduates or graduate students in astronomy and astrophysics. It starts from first principles in order to fill gaps in students' backgrounds, make teaching easier for professors who are not expert radio astronomers, and provide a useful reference to the essential equations used by practitioners. This unique textbook reflects the fact that students of multiwavelength astronomy typically can afford to spend only one semester studying the observational techniques particular to each wavelength band. Essential Radio Astronomy presents only the most crucial concepts—succinctly and accessibly. It covers the general principles behind radio telescopes, receivers, and digital backends without getting bogged down in engineering details. Emphasizing the physical processes in radio sources, the book's approach is shaped by the view that radio astrophysics owes more to thermodynamics than electromagnetism. Proven in the classroom and generously illustrated throughout, Essential Radio Astronomy is an invaluable resource for students and researchers alike. The only textbook specifically designed for a one-semester course in radio astronomy Starts from first principles Makes teaching easier for astronomy professors who are not expert radio astronomers Emphasizes the physical processes in radio sources Covers the principles behind radio telescopes and receivers Provides the essential equations and fundamental constants used by practitioners Supplementary website includes lecture notes, problem sets, exams, and links to interactive demonstrations An online illustration package is available to professors
The revolution in digital technology that has had so many obvious effects in recent decades has not spared the field of astronomy. It has led to an enormous improvement in astronomers' ability to study the "time domain," the expected and unexpected ways in which celestial objects change on timescales ranging from milliseconds to centuries. In the field of radio astronomy a variety of advances have led to a new breed of observatories that are orders of magnitude more efficient at surveying the sky than previous facilities. These new observatories produce data at prodigous rates, however, and require sophisticated analysis to take full advantage of their capabilities. With several major facilities coming online in the next few years, there is an urgent need to prove that terabytes of data can be reliably turned into genuine astrophysical results. This dissertation develops tools and techniques for coping with this challenge and applies them to data obtained with the Allen Telescope Array (ATA), a pioneering next-generation radio observatory located in Northern California. The ATA was built from the ground up to be a fast survey instrument, incorporating a suite of the new technologies that figure prominently in the new telescopes. I develop and describe miriad-python, a framework for the rapid development of interferometric analysis software that is used in a variety of ways in my subsequent research. I also present a robust software system for executing multiple observing campaigns cooperatively ("commensally") at the ATA. Data from the ATA are difficult to analyze due to nontraditional features such as a large instantaneous field of view; continuous coverage of a large, interference-prone frequency range; and broadband, movable feeds; I describe and implement several methods for coping with these challenges. This technical work is driven by the needs of a variety of astrophysical applications. I use broadband spectra of starforming galaxies to investigate the "calorimeter" interpretation of their cosmic ray energetics. The data are consistent with a recent hypothesis that the magnetic fields in these galaxies are stronger than traditionally thought. I use the survey capabilities of the ATA to conduct ASGARD, a large survey of the Galactic component of the dynamic radio sky, which has remained poorly-explored due to the limitations of previous obseratories and the technical challenges involved. I discuss in detail the methods used to analyze the data and provide catalogs, maps, completeness functions, and variability statistics. I map extended radio structures in Galactic fields and show how they can be subtracted from the data to simplify the search for transient Galactic sources. I limit the density of transient sources brighter than 10 mJy to be -2 at 95% confidence. One of the areas of emphasis in this survey was the fascinating system Cygnus X-3, which shows prominent flares across the electromagnetic spectrum. Observations from 2010 May show a bright (1 Jy) radio flare followed by a 4.3[sigma] [gamma]-ray flare (E> 100 MeV) ~ 1.5 days later. This timing is inconsistent with standard inverse-Compton models, suggesting that multiple mechanisms may be responsible for the system's high-energy emission.
By the late nineteenth century, engineers and experimental scientists generally knew how radio waves behaved, and by 1901 scientists were able to manipulate them to transmit messages across long distances. What no one could understand, however, was why radio waves followed the curvature of the Earth. Theorists puzzled over this for nearly twenty years before physicists confirmed the zig-zag theory, a solution that led to the discovery of a layer in the Earth’s upper atmosphere that bounces radio waves earthward—the ionosphere. In Probing the Sky with Radio Waves, Chen-Pang Yeang documents this monumental discovery and the advances in radio ionospheric propagation research that occurred in its aftermath. Yeang illustrates how the discovery of the ionosphere transformed atmospheric science from what had been primarily an observational endeavor into an experimental science. It also gave researchers a host of new theories, experiments, and instruments with which to better understand the atmosphere’s constitution, the origin of atmospheric electricity, and how the sun and geomagnetism shape the Earth’s atmosphere. This book will be warmly welcomed by scholars of astronomy, atmospheric science, geoscience, military and institutional history, and the history and philosophy of science and technology, as well as by radio amateurs and electrical engineers interested in historical perspectives on their craft.
