University of Groningen the Logistic Design of the LOFAR Radio Telescope Schakel, L.P
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Radio Astronomy
Theme 8: Beyond the Visible I: radio astronomy Until the turn of the 17th century, astronomical observations relied on the naked eye. For 250 years after this, although astronomical instrumentation made great strides, the radiation being detected was still essentially confined to visible light (Herschel discovered infrared radiation in 1800, and the advent of photography opened up the near ultraviolet, but these had little practical significance). This changed dramatically in the mid-20th century with the advent of radio astronomy. 8.1 Early work: Jansky and Reber The atmosphere is transparent to visible light, but opaque to many other wavelengths. The only other clear “window” of transparency lies in the radio region, between 1 mm and 30 m wavelength. One might expect that the astronomical community would deliberately plan to explore this region, but in fact radio astronomy was born almost accidentally, with little if any involvement of professional astronomers. Karl Jansky (1905−50) was a radio engineer at Bell Telephone. In 1932, while studying the cause of interference on the transatlantic radio-telephone link, he discovered that part of the interference had a periodicity of one sidereal day (23h 56m), and must therefore be coming from an extraterrestrial source. By considering the time at which the interference occurred, Jansky identified the source as the Milky Way. This interesting finding was completely ignored by professional astronomers, and was followed up only by the radio engineer and amateur astronomer Grote Reber (1911−2002). Reber built a modern-looking paraboloid antenna and constructed maps of the radio sky, which also failed to attract significant professional attention. -
Astronomische Waarneemtechnieken (Astronomical Observing Techniques) Based on Lectures by Bernhard Brandl Lecture 8: Radio 1
Astronomische Waarneemtechnieken (Astronomical Observing Techniques) Based on lectures by Bernhard Brandl Lecture 8: Radio 1. Introducon 2. Radio Emission 3. Observing 4. Antenna Technology 5. Receiver Technology 6. Back Ends 7. Calibraons (c) National Radio Astronomy Observatory / Associated Universities, Inc. / National Science Foundation The First Radio Astronomers http://en.wikipedia.org/wiki/Radio_telescope http://en.wikipedia.org/wiki/Radio_astronomy Grote Reber (1911-2002) Karl Guthe Jansky (1905-1950) Karl Jansky built (at Bell Telephone Laboratories) antenna to receive radio waves at 20.5 MHz (λ~14.6m) à “turntable” of 30m×6m à first detection of astronomical radio waves (à 1 Jy = 10−26 W m−2 Hz−1) Grote Reber extended Jansky's work, conducted first radio sky survey. For nearly a decade he was the world's only radio astronomer. Radio Astronomy Discoveries • radio (synchrotron) emission of the Milky Way (1933) • first discrete cosmic radio sources: supernova remnants and radio galaxies (1948) • 21-cm line of atomic hydrogen (1951) • Quasi Stellar Objects (1963) • Cosmic Microwave Background (1965) • Interstellar molecules ó Star formation (1968) • Pulsars (1968) Radio Observations through the Atmosphere • Radio window from ~10 MHz (30m) to 1 THz (0.3mm) • Low-frequency limit given by (reflecting) ionosphere • High frequency limit given by molecular transitions of atmospheric H2O and N2. Radio Wavelengths: PhotonsàElectric Fields • Directly measure electric fields of electro- magnetic waves • Electric fields excite currents in antennae • Currents can be amplified and split electrically. Radio Emission Mechanisms Most important astronomical radio emission mechanisms 1. Synchrotron emission 2. Free-free emission (thermal Bremsstrahlung) 3. Thermal (blackbody) emission (also from dust grains) 4. -
Z´AKLADY ASTRONOMIE a ASTROFYZIKY II Látka Prednášená
ZAKLADY´ ASTRONOMIE A ASTROFYZIKY II L´atka pˇredn´aˇsen´aM. Wolfem Na z´akladˇesv´ych pozn´amekz pˇredn´aˇskya dalˇs´ıliteratury sepsal M. B´ılek, korektury, doplˇnkyM. Zejda Verze 1: 6. z´aˇr´ı2010 Toto je zat´ımpracovn´ıverze skript. Je ne´upln´aa m˚uˇzeobsahovat menˇs´ıfaktick´echyby. V pˇr´ıpadˇe,ˇzenˇejakouobjev´ıte,nebo se v´ambude zd´atnˇejak´aˇc´asttextu nesrozumiteln´a, upozornˇetepros´ımautora nebo pˇredn´aˇsej´ıc´ıho.Doch´azkana pˇredn´aˇskuse doporuˇcuje. 2 Obsah 1 Atmosf´erick´aa vnˇeatmosf´erick´aastronomie 5 1.1 Uvod.......................................´ 5 1.2 Vliv atmosf´ery na astronomick´apozorov´an´ı. .5 1.2.1 Extinkce v atmosf´eˇre . .5 1.2.2 Seeing . .8 1.3 Bal´onov´aastronomie . .8 1.4 Druˇzicov´aastronomie . .9 2 Optick´aastronomie 13 2.1 Optick´edalekohledy . 13 2.1.1 Konstrukce dalekohled˚u . 13 2.1.2 Charakteristiky dalekohledu . 21 2.1.3 Optick´evady dalekohled˚u . 25 2.1.4 Okul´ary . 29 2.1.5 Filtry . 35 2.1.6 Mont´aˇze . 36 2.2 Optick´edetektory a jejich vyuˇzit´ıve fotometrii . 38 2.2.1 Nˇekter´eobecn´echarakteristiky fotometrick´ych detektor˚u. 39 2.2.2 Oko . 39 2.2.3 Fotografick´aemulze . 44 2.2.4 Foton´asobiˇce . 46 2.2.5 CCD . 48 2.3 Spektrografy . 53 2.3.1 Hranolov´yspektrograf . 55 2.3.2 Mˇr´ıˇzkov´yspektrograf . 55 3 R´adiov´aastronomie 63 4 Infraˇcerven´aastronomie 65 5 Rentgenov´aastronomie 67 6 Astronomie gama z´aˇren´ı 69 3 7 Astronomie gravitaˇcn´ıch vln 73 8 Neutrinov´aastronomie 75 9 Pˇr´ıstroje sluneˇcn´ıfyziky 79 10 Doporuˇcen´aliteratura 83 4 Kapitola 1 Atmosf´erick´aa vnˇeatmosf´erick´a astronomie 1.1 Uvod´ Pozorov´an´ıvesm´ırn´ych tˇelesz povrchu Zemˇe,na dnˇevzduˇsn´ehooce´anu, je pro astron- omy velmi omezuj´ıc´ı.Zemsk´aatmosf´era velmi dobˇrefiltruje z´aˇren´ıpˇrich´azej´ıc´ız vesm´ıru na povrch Zemˇe.V´ysledkem je, ˇzeˇzeZemˇem˚uˇzemevidˇetjen velmi omezen´erozsahy vl- nov´ych d´elekz´aˇren´ı,naz´yvan´a okna\. -
Essential Radio Astronomy
February 2, 2016 Time: 09:25am chapter1.tex © Copyright, Princeton University Press. No part of this book may be distributed, posted, or reproduced in any form by digital or mechanical means without prior written permission of the publisher. 1 Introduction 1.1 AN INTRODUCTION TO RADIO ASTRONOMY 1.1.1 What Is Radio Astronomy? Radio astronomy is the study of natural radio emission from celestial sources. The range of radio frequencies or wavelengths is loosely defined by atmospheric opacity and by quantum noise in coherent amplifiers. Together they place the boundary be- tween radio and far-infrared astronomy at frequency ν ∼ 1 THz (1 THz ≡ 1012 Hz) or wavelength λ = c/ν ∼ 0.3 mm, where c ≈ 3 × 1010 cm s−1 is the vacuum speed of light. The Earth’s ionosphere sets a low-frequency limit to ground-based radio astronomy by reflecting extraterrestrial radio waves with frequencies below ν ∼ 10 MHz (λ ∼ 30 m), and the ionized interstellar medium of our own Galaxy absorbs extragalactic radio signals below ν ∼ 2 MHz. The radio band is very broad logarithmically: it spans the five decades between 10 MHz and 1 THz at the low-frequency end of the electromagnetic spectrum. Nearly everything emits radio waves at some level, via a wide variety of emission mechanisms. Few astronomical radio sources are obscured because radio waves can penetrate interstellar dust clouds and Compton-thick layers of neutral gas. Because only optical and radio observations can be made from the ground, pioneering radio astronomers had the first opportunity to explore a “parallel universe” containing unexpected new objects such as radio galaxies, quasars, and pulsars, plus very cold sources such as interstellar molecular clouds and the cosmic microwave background radiation from the big bang itself. -
Wide-Band, Low-Frequency Pulse Profiles of 100 Radio Pulsars With
A&A 586, A92 (2016) Astronomy DOI: 10.1051/0004-6361/201425196 & c ESO 2016 Astrophysics Wide-band, low-frequency pulse profiles of 100 radio pulsars with LOFAR M. Pilia1,2, J. W. T. Hessels1,3,B.W.Stappers4, V. I. Kondratiev1,5,M.Kramer6,4, J. van Leeuwen1,3, P. Weltevrede4, A. G. Lyne4,K.Zagkouris7, T. E. Hassall8,A.V.Bilous9,R.P.Breton8,H.Falcke9,1, J.-M. Grießmeier10,11, E. Keane12,13, A. Karastergiou7 , M. Kuniyoshi14, A. Noutsos6, S. Osłowski15,6, M. Serylak16, C. Sobey1, S. ter Veen9, A. Alexov17, J. Anderson18, A. Asgekar1,19,I.M.Avruch20,21,M.E.Bell22,M.J.Bentum1,23,G.Bernardi24, L. Bîrzan25, A. Bonafede26, F. Breitling27,J.W.Broderick7,8, M. Brüggen26,B.Ciardi28,S.Corbel29,11,E.deGeus1,30, A. de Jong1,A.Deller1,S.Duscha1,J.Eislöffel31,R.A.Fallows1, R. Fender7, C. Ferrari32, W. Frieswijk1, M. A. Garrett1,25,A.W.Gunst1, J. P. Hamaker1, G. Heald1, A. Horneffer6, P. Jonker20, E. Juette33, G. Kuper1, P. Maat1, G. Mann27,S.Markoff3, R. McFadden1, D. McKay-Bukowski34,35, J. C. A. Miller-Jones36, A. Nelles9, H. Paas37, M. Pandey-Pommier38, M. Pietka7,R.Pizzo1,A.G.Polatidis1,W.Reich6, H. Röttgering25, A. Rowlinson22, D. Schwarz15,O.Smirnov39,40, M. Steinmetz27,A.Stewart7, J. D. Swinbank41,M.Tagger10,Y.Tang1, C. Tasse42, S. Thoudam9,M.C.Toribio1,A.J.vanderHorst3,R.Vermeulen1,C.Vocks27, R. J. van Weeren24, R. A. M. J. Wijers3, R. Wijnands3, S. J. Wijnholds1,O.Wucknitz6,andP.Zarka42 (Affiliations can be found after the references) Received 20 October 2014 / Accepted 18 September 2015 ABSTRACT Context. -
Great Discoveries Made by Radio Astronomers During the Last Six Decades and Key Questions Today
17_SWARUP (G-L)chiuso_074-092.QXD_Layout 1 01/08/11 10:06 Pagina 74 The Scientific Legacy of the 20th Century Pontifical Academy of Sciences, Acta 21, Vatican City 2011 www.pas.va/content/dam/accademia/pdf/acta21/acta21-swarup.pdf Great Discoveries Made by Radio Astronomers During the Last Six Decades and Key Questions Today Govind Swarup 1. Introduction An important window to the Universe was opened in 1933 when Karl Jansky discovered serendipitously at the Bell Telephone Laboratories that radio waves were being emitted towards the direction of our Galaxy [1]. Jansky could not pursue investigations concerning this discovery, as the Lab- oratory was devoted to work primarily in the field of communications. This discovery was also not followed by any astronomical institute, although a few astronomers did make proposals. However, a young electronics engi- neer, Grote Reber, after reading Jansky’s papers, decided to build an inno- vative parabolic dish of 30 ft. diameter in his backyard in 1935 and made the first radio map of the Galaxy in 1940 [2]. The rapid developments of radars during World War II led to the dis- covery of radio waves from the Sun by Hey in 1942 at metre wavelengths in UK and independently by Southworth in 1942 at cm wavelengths in USA. Due to the secrecy of the radar equipment during the War, those re- sults were published by Southworth only in 1945 [3] and by Hey in 1946 [4]. Reber reported detection of radio waves from the Sun in 1944 [5]. These results were noted by several groups soon after the War and led to intensive developments in the new field of radio astronomy. -
Fundamentals of Radio Astronomy
• 4.85 GHz radio image The Radio Sky at 4.85 GHz • 45 degrees wide • brightest irregular sources are clouds of ionized hydrogen The Radio Universe Dr. Chuck Higgins Middle Tennessee State University • Supernovae remnants appear as faint radio rings • Radio "stars" scattered over the sky - most are luminous radio galaxies 9 (c) National Radio Astronomy Observatory / Associated or quasars (average distance > 5 x 10 ly) Universities, Inc. / National Science Foundation • 4.85 GHz radio image The Radio Sky at 4.85 GHz • 45 degrees wide • brightest irregular sources are clouds of ionized hydrogen Outline 1.The Radio Sky and the EM Spectrum 2.Radio Telescopes 3.What We Learn and Major Discoveries 4.Sources of Radio Emission 5.Examples – Sun, Planets, Stars, Pulsars, Galaxies, etc. 6.Radio JOVE • Supernovae remnants appear as faint radio rings • Radio "stars" scattered over the sky - most are luminous radio galaxies 9 (c) National Radio Astronomy Observatory / Associated or quasars (average distance > 5 x 10 ly) Universities, Inc. / National Science Foundation Radio Astronomy the study of radio waves originating outside Earth’s atmosphere Radio Window 1 THz – 10 MHz 0.3 mm – 30 m Credit: Adapted from STScI/JHU/NASA Radio Telescopes Concept Drawing of the Square Kilometer Array, Australia Green Bank Telescope (NRAO, NSF) Fast Radio Telescope (China) 500 m dish VLA, New Mexico (NRAO, NSF) Itty Bitty Radio Telescope Radio Telescopes Radio Waves Image Credit: Windows to the Universe Radio waves = electromagnetic waves generally caused by moving charged -
Radio Frequency Interference (Rfi) Mapping for Radio Astronomy in Peninsular Malaysia
RADIO FREQUENCY INTERFERENCE (RFI) MAPPING FOR RADIO ASTRONOMY IN PENINSULAR MALAYSIA ROSLAN UMAR FACULTY OF SCIENCE UNIVERSITY OF MALAYA KUALA LUMPUR 2014 RADIO FREQUENCY INTERFERENCE (RFI) MAPPING FOR RADIO ASTRONOMY IN PENINSULAR MALAYSIA ROSLAN UMAR THESIS SUBMITTED IN FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF PHYSICS FACULTY OF SCIENCE UNIVERSITY OF MALAYA KUALA LUMPUR 2014 UNIVERSITI MALAYA ORIGINAL LITERARY WORK DECLARATION Name of Candidate: Roslan b. Umar (I.C./Passport No.:800305115235) Registration/Matrix No.: SHC100045 Name of Degree: Doctor of Philosophy Title of Project Paper/Research Report/Dissertation/Thesis (“this Work”): Radio Frequency Interference (RFI) Mapping for Radio Astronomy In Peninsular Malaysia Field of Study: Radio Astronomy, I do solemnly and sincerely declare that: (1) I am the sole author/writer of this Work; (2) This work is original; (3) Any use of any work in which copyright exists was done by way of fair dealing and for permitted purposes and any excerpt or extract from, or reference to or reproduction of any copyright work has been disclosed expressly and sufficiently and the title of the Work and its authorship have been acknowledged in this Work; (4) I do not have any actual knowledge nor do I ought reasonably to know that the making of this work constitutes an infringement of any copyright work; (5) I hereby assign all and every rights in the copyright to this Work to the University of Malaya (“UM”), who henceforth shall be owner of the copyright in this Work and that any reproduction or use in any form or by any means whatsoever is prohibited without the written consent of UM having been first had and obtained; (6) I am fully aware that if in the course of making this Work I have infringed any copy- right whether intentionally or otherwise, I may be subject to legal action or any other action as may be determined by UM. -
ASTRONET ERTRC Report
Radio Astronomy in Europe: Up to, and beyond, 2025 A report by ASTRONET’s European Radio Telescope Review Committee ! 1!! ! ! ! ERTRC report: Final version – June 2015 ! ! ! ! ! ! 2!! ! ! ! Table of Contents List%of%figures%...................................................................................................................................................%7! List%of%tables%....................................................................................................................................................%8! Chapter%1:%Executive%Summary%...............................................................................................................%10! Chapter%2:%Introduction%.............................................................................................................................%13! 2.1%–%Background%and%method%............................................................................................................%13! 2.2%–%New%horizons%in%radio%astronomy%...........................................................................................%13! 2.3%–%Approach%and%mode%of%operation%...........................................................................................%14! 2.4%–%Organization%of%this%report%........................................................................................................%15! Chapter%3:%Review%of%major%European%radio%telescopes%................................................................%16! 3.1%–%Introduction%...................................................................................................................................%16! -
Thesis Is Submited in Partial Fulfilment of the Requirements for the Award of the Degree of Doctor of Philosophy of the University of Portsmouth
Techniques for Cosmological Analysis of Next Generation Low to Mid-Frequency Radio Data Michael Tarr Department of Technology THE THESIS IS SUBMITED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF DOCTOR OF PHILOSOPHY OF THE UNIVERSITY OF PORTSMOUTH May 2018 Declaration Whilst registered as a candidate for the above degree, I have not been registered for any other research award. The results and conclusions embodied in this thesis are the work of the named candidate and have not been submitted for any other academic award. This dissertation contains 51,523 words not including appendices, bibliography, footnotes, tables and equations, and has 68 figures. Michael Tarr May 2018 Acknowledgements First, I would like to give my most sincere thanks to David. It goes without saying that I can not imagine having completed this work without you. Your enthusiasm and belief in me has been a constant source of motivation from day one to the eleventh hour. You are an inspiration and model of a perfect superior. I cannot overstate how much I appchiate your effort, and I am eternally grateful. My love and thanks also to my parents, who have provided nothing but loving support, despite all my whims and phases. I can only hope it was all worth it to find something I have finally stuck with. Thanks should also go to Xan and Matthew, for taking precious time away from their own research to indulge my pet machine learning project. I owe you both and hope to always be friends. Rebecca1, save the final thanks for you. -
The Search For
THE SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE Proceedings of an NRAO Workshop held at the National Radio Astronomy Observatory Green Bank, West Virginia May 20, 21, 22, 1985 1960 1985 Honoring the 25th Anniversary of Project OZMA Edited by K. I. Kellermann and G. A. Seielstad THE SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE Proceedings of an NRAO Workshop held at the National Radio Astronomy Observatory Green Bank, West Virginia May 20, 21, 22, 1985 Edited by K. I. Kellermann and GL A. Seielstad Workshop Na 11 Distributed by: National Radio Astronomy Observatory P.O. Box 2 Green Bank, WV 24944-0002 USA The National Radio Astronomy Observatory is operated by Associated Universities, Inc., under contract with the National Science Foundation. Copyright © 1986 NRAO/AUI. All Rights Reserved. CONTENTS Page I. KEYNOTE ADDRESS Life in Space and Humanity on Earth . Sebastian von Hoeimer 3 II. HISTORICAL PERSPECTIVE Project OZMA Frank D. Drake 17 Project OZMA - How It Really Was J. Fred Crews 27 Evolution of Our Thoughts on the Best Strategy for SETI Michael D. Papagiannis 31 III. SEARCH STRATEGIES The Search for Biomolecules in Space Lewis E. Snyder 39 Mutual Help in SETI's David H. Frisch 51 A Symbiotic SETI Search Thomas M. Bania 61 Should the Search be Made Optically? John J. Broderiok 67 A Search for SETI Targets Jane L. Russell 69 A Milky Way Search Strategy for Extra¬ terrestrial Intelligence .... Woodruff T. Sullivan, III 75 IV. CURRENT PROGRAMS SETI Observations Worldwide Jill C. Tarter 79 Ultra-Narrowband SETI at Harvard/Smithsonian . Paul Horowitz 99 The NASA SETI Program: An Overview Bernard M. -
Instrumentation for Wide Bandwidth Radio Astronomy
Instrumentation for Wide Bandwidth Radio Astronomy Thesis by Glenn Evans Jones In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy California Institute of Technology Pasadena, California 2010 (Defended September 25, 2009) ii c 2010 Glenn Evans Jones All Rights Reserved iii To my family. iv Acknowledgements Since I was very young I have been fascinated by radio telescopes, but despite a keen interest in other areas of electronics, I never learned how they were used until I began working with my research advisor, Sandy Weinreb. As a fellow electronics and technology enthusiast, I cannot imagine a better person to introduce me to the field of radio astronomy which has steadily become my career. From the very beginning, he has been a tireless advocate for me while sharing his broad experience across the gamut of radio astronomy instrumentation and observations. One of the most important ways in which Sandy has influenced me professionally is by pursuing every available opportunity to introduce me to members of the radio astronomy community. I also very much appreciate the support provided by my academic advisor, Dave Rutledge. Dave provided a wide range of useful suggestions and encouragement during group meetings, and looked out for me from the very beginning. Each of the other members of my thesis committee also deserves special thanks apart from my gratitude to them for serving on the committee. P.P. Vaidyanathan introduced me to digital signal processing and his clear, insightful lectures helped to inspire my interest in the field. Tony Read- head's courses on radio astronomy instrumentation and radiative processes significantly improved my understanding of the details of radio astronomy.