The Exploration of the Unknown
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Short History of Radio Astronomy Jansky – January 1932
Short History of Radio Astronomy Jansky – January 1932 Modified Bruce Array: Harald Friis design December 1932 Jansky’s 1932 Data Grote Reber- 1937 9.5 m Parabolic Reflector! Strip Chart output From Strip Chart to Contour Plot… 1940 Ap. J. paper…barely Reber’s 160 MHz contour map published in the ApJ in 1944. This shows the northern sky in equatorial coordinates. The Reber’s 160 MHz contour map published in the ApJ in 1944. This shows the northern sky in equatorial coordinates. The Reber’s 160 MHz contour map published in the ApJ in 1944. This shows the northern sky in equatorial coordinates. The Reber’s 160 MHz contour map published in the ApJ in 1944. This shows the northern sky in equatorial coordinates. The Jan Oort & Hendrik van de Hulst Lieden Observatory 1944 Predicted HI Line Detection of Hydrogen Line …… Ewen & Purcell 21 cm HI Line (1420 MHz) Purcell HI Receiver: Doc Ewen (1951) Milky Way in Optical Origin of SETI Nature, 1959 Philip Morrison 1959 Project Ozma: April 6, 1960 Tau Ceti & Epsilon Eridani Cosmic Background: Penzias & Wilson 1965 • 20 ft Echo Horn (Sugar Scoop): • Harald Friis design Pulsars: Bell and Hewish 1967 Detection of Pulsars: ~100ft of chart/day Chart recording of the pulsar Examples of scintillating detection and an interference signal somewhat later in time. Fast chart recording of pulsar emission (LGM nomenclature is “Little Green Arecibo Message: 1974 Big Ear Radio Telescope OSU Wow! Signal, Aug. 15, 1977 Sagitarius, Chi Sagittari star group NRAO 36ft Kitt Peak Telescope The Drake Equation The Drake equation -
Antony Hewish
PULSARS AND HIGH DENSITY PHYSICS Nobel Lecture, December 12, 1974 by A NTONY H E W I S H University of Cambridge, Cavendish Laboratory, Cambridge, England D ISCOVERY OF P U L S A R S The trail which ultimately led to the first pulsar began in 1948 when I joined Ryle’s small research team and became interested in the general problem of the propagation of radiation through irregular transparent media. We are all familiar with the twinkling of visible stars and my task was to understand why radio stars also twinkled. I was fortunate to have been taught by Ratcliffe, who first showed me the power of Fourier techniques in dealing with such diffraction phenomena. By a modest extension of existing theory I was able to show that our radio stars twinkled because of plasma clouds in the ionosphere at heights around 300 km, and I was also able to measure the speed of ionospheric winds in this region (1) . My fascination in using extra-terrestrial radio sources for studying the intervening plasma next brought me to the solar corona. From observations of the angular scattering of radiation passing through the corona, using simple radio interferometers, I was eventually able to trace the solar atmo- sphere out to one half the radius of the Earth’s orbit (2). In my notebook for 1954 there is a comment that, if radio sources were of small enough angular size, they would illuminate the solar atmosphere with sufficient coherence to produce interference patterns at the Earth which would be detectable as a very rapid fluctuation of intensity. -
The Exploration of the Unknown
The exploration of the unknown K. I. Kellermann1 National Radio Astronomy Observatory Charlottesville, VA, U.S.A. E-mail: [email protected] J. M. Cordes Cornell University Ithaca, NY E-mail: [email protected] R.D. Ekers CSIRO Sydney, Australia E-mail: [email protected] J. Lazio Naval Research Lab Washington, D.C., USA E-mail: [email protected] Peter Wilkinson Jodrell Bank Center for Astrophsyics Manchester, UK E-mail: [email protected] Accelerating the Rate of Astronomical Discovery - sps5 Rio de Janeiro, Brazil August 11–14 2009 1 Speaker Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it Summary The discovery of cosmic radio emission by Karl Jansky in the course of searching for the source of interference to telephone communications and the instrumental advances which followed, have led to a series of new paradigm changing astronomical discoveries. These include the non-thermal emission from stars and galaxies, electrical storms on the Sun and Jupiter, radio galaxies, AGN, quasars and black holes, pulsars and neutron stars, the CMB, interstellar molecules and giant molecular clouds; the anomalous rotation of Venus and Mercury, cosmic masers, extra-solar planets, precise tests of gravitational bending, gravitational lensing, the first experimental evidence for gravitational radiation, and the first observational evidence for cosmic evolution. These discoveries, which to a large extent define much of modern astrophysical research, have resulted in eight Nobel Prize winners. They were the result of the right people being in the right place at the right time using powerful new instruments, which in many cases they had designed and built. -
History of Radio Astronomy
History of Radio Astronomy Reading for High School Students Getsemary Báez Introduction form of radiation involved (soon known as electro- Radio Astronomy, a field that has strongly magnetic waves). Nevertheless, it was Oliver Heavi- evolved since the end of World War II, has become side who in conjunction with Willard Gibbs in 1884 one of the most important tools of astronomical ob- modified the equations and put them into modern servations. Radio astronomy has been responsible for vector notation. a great part of our understanding of the universe, its A few years later, Heinrich Hertz (1857- formation, composition, interactions, and even pre- 1894) demonstrated the existence of electromagnetic dictions about its future path. This article intends to waves by constructing a device that had the ability to inform the public about the history of radio astron- transmit and receive electromagnetic waves of about omy, its evolution, connection with solar studies, and 5m wavelength. This was actually the first radio the contribution the STEREO/WAVES instrument on wave transmitter, which is what we call today an LC the STEREO spacecraft will have on the study of oscillator. Just like Maxwell’s theory predicted, the this field. waves were polarized. The radiation emissions were detected using a 1mm thin circle of copper wire. Pre-history of Radio Waves Now that there is evidence of electromag- It is almost impossible to depict the most im- netic waves, the physicist Max Planck (1858-1947) portant facts in the history of radio astronomy with- was responsible for a breakthrough in physics that out presenting a sneak peak where everything later developed into the quantum theory, which sug- started, the development and understanding of the gests that energy had to be emitted or absorbed in electromagnetic spectrum. -
Radio Astronomy
Edition of 2013 HANDBOOK ON RADIO ASTRONOMY International Telecommunication Union Sales and Marketing Division Place des Nations *38650* CH-1211 Geneva 20 Switzerland Fax: +41 22 730 5194 Printed in Switzerland Tel.: +41 22 730 6141 Geneva, 2013 E-mail: [email protected] ISBN: 978-92-61-14481-4 Edition of 2013 Web: www.itu.int/publications Photo credit: ATCA David Smyth HANDBOOK ON RADIO ASTRONOMY Radiocommunication Bureau Handbook on Radio Astronomy Third Edition EDITION OF 2013 RADIOCOMMUNICATION BUREAU Cover photo: Six identical 22-m antennas make up CSIRO's Australia Telescope Compact Array, an earth-rotation synthesis telescope located at the Paul Wild Observatory. Credit: David Smyth. ITU 2013 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. - iii - Introduction to the third edition by the Chairman of ITU-R Working Party 7D (Radio Astronomy) It is an honour and privilege to present the third edition of the Handbook – Radio Astronomy, and I do so with great pleasure. The Handbook is not intended as a source book on radio astronomy, but is concerned principally with those aspects of radio astronomy that are relevant to frequency coordination, that is, the management of radio spectrum usage in order to minimize interference between radiocommunication services. Radio astronomy does not involve the transmission of radiowaves in the frequency bands allocated for its operation, and cannot cause harmful interference to other services. On the other hand, the received cosmic signals are usually extremely weak, and transmissions of other services can interfere with such signals. -
Adventures in Radio Astronomy Instrumentation and Signal Processing
Adventures in Radio Astronomy Instrumentation and Signal Processing by Peter Leonard McMahon Submitted to the Department of Electrical Engineering in partial fulfillment of the requirements for the degree of Master of Science in Electrical Engineering at the University of Cape Town July 2008 Supervisor: Professor Michael Inggs Co-supervisors: Dr Dan Werthimer, CASPER1, University of California, Berkeley Dr Alan Langman, Karoo Array Telescope arXiv:1109.0416v1 [astro-ph.IM] 2 Sep 2011 1Center for Astronomy Signal Processing and Electronics Research Abstract This thesis describes the design and implementation of several instruments for digi- tizing and processing analogue astronomical signals collected using radio telescopes. Modern radio telescopes have significant digital signal processing demands that are typically best met using custom processing engines implemented in Field Pro- grammable Gate Arrays. These demands essentially stem from the ever-larger ana- logue bandwidths that astronomers wish to observe, resulting in large data volumes that need to be processed in real time. We focused on the development of spectrometers for enabling improved pulsar2 sci- ence on the Allen Telescope Array, the Hartebeesthoek Radio Observatory telescope, the Nan¸cay Radio Telescope, and the Parkes Radio Telescope. We also present work that we conducted on the development of real-time pulsar timing instrumentation. All the work described in this thesis was carried out using generic astronomy pro- cessing tools and hardware developed by the Center for Astronomy Signal Processing and Electronics Research (CASPER) at the University of California, Berkeley. We successfully deployed to several telescopes instruments that were built solely with CASPER technology, which has helped to validate the approach to developing radio astronomy instruments that CASPER advocates. -
NRAO Enews Volume 12, Issue 5 • 13 June 2019
NRAO eNews Volume 12, Issue 5 • 13 June 2019 Upcoming Events NRAO Community Day at UMBC (https://science.nrao.edu/science/meetings/2019/umbc19/index) Jun 13 14, 2019 | Baltimore, MD CASCA 2019 (http://www.physics.mcgill.ca/casca2019/) Jun 17 20, 2019 | Montréal, Québec Radio/mm Astrophysical Frontiers in the Next Decade (http://go.nrao.edu/ngVLA19) Jun 25 27, 2019 | Charlottesville, VA 7th VLA Data Reduction Workshop (http://go.nrao.edu/vladrw) Oct 7 18, 2019 | Socorro, NM ALMA2019: Science Results and CrossFacility Synergies (http://www.eso.org/sci/meetings/2019/ALMA2019Cagliari.html) Oct 14 18, 2019 | Cagliari, Sardinia, Italy Semester 2019B Proposal Outcomes Lewis Ball The NRAO has completed the Semester 2019B proposal review and time allocation process (https://science.nrao.edu/observing/proposal-types/peta) for the Very Large Array (VLA) (https://science.nrao.edu/facilities/evla) and the Very Long Baseline Array (VLBA) (https://science.nrao.edu/facilities/vlba) . For the VLA a single configuration (the D array) will be available in the 19B semester and 124 new proposals were received by the 1 February 2019 submission deadline including one large and sixteen time critical (triggered) proposals. The oversubscription rate (by proposal number) was 2.5 and the proposal pressure (hours requested over hours available) was 2.1, both of which are similar to recent semesters. For the VLBA 27 new proposals were submitted, including two large proposals and one triggered proposal. The oversubscription rate was 2.1 and the proposal pressure was 2.3, both of which are similar to recent semesters. -
Martin Ryle (1918–1984)
ARTICLE-IN-A-BOX Martin Ryle (1918–1984) Martin Ryle was one of the pioneers of the field of radio astronomy which made rapid progress in the decades immediately following the Second World War. He was awarded the Nobel Prize in Physics for developing the technique known as ‘aperture synthesis’. This overcame what appeared to be a fundamental limitation of using radio waves. The smallest angle θmin (in ra- dians) at which details can be made out in an image of the sky made by a telescope depends on its diameter D and the wavelength λ. This is called the angular resolution and is given by the famous equation θmin = λ/D. Any finer detail such as the separation of two stars get blurred out. At a radio wavelength of 0.5 metres and a telescope of diameter of 50 metres, 1 this comes out to be 100 radian or a little more than half a degree – the size of the moon as seen from the Earth. The early pictures of the sky in radio waves were very crude compared to those made with visible light, typical wavelength 0.5 micrometres, a million times smaller. Making a radio dish of size even 100 times an optical telescope mirror would still leave radio pictures ten thousand times poorer than those made with visible light. Aperture synthesis broke this barrier, and today radio astronomy produces the sharpest images at any wavelength! The background to the emergence of radio astronomy, and this particular technique are explained in the article by Chengalur in this issue (p.165). -
2020 the Pathfinder View of the Sky LEGEND Canadian Hydrogen Intensity Mapping European VLBI Experiment (CHIME) - Network (EVN) - Canada Europe
Calendar 2020 The Pathfinder View of the Sky LEGEND Canadian Hydrogen Intensity Mapping European VLBI Experiment (CHIME) - Network (EVN) - Canada Europe enhanced Multi Element Remotely NenuFAR - France Linked Interferometer Network (e-MERLIN) - United Kingdom Low Frequency Array (LOFAR) - the MeerKAT Radio Netherlands Telescope - South Africa Five-hundred-meter Aperture Spherical Australian SKA Telescope (FAST) - Pathfinder (ASKAP) - China Australia (CHIME) Giant Metrewave Murchison Widefield Radio Telescope Array (MWA) - (GMRT) - India Australia VLBI Exploration of Effelsberg 100m Members of the SKA Organisation African Partner Countries Radio Astrometry Radio Telescope - Host Countries: Australia, South Africa, United Kingdom (VERA) - Japan Germany In the lead up to the SKA, many new groundbreaking radio elusive Fast Radio Bursts. They’re also allowing engineers The 2020 SKA calendar, called The Pathfinder View of the astronomy facilities have sprung up around the world in to develop new technical solutions like aperture arrays or Sky and featuring a small selection of the results already the past 10 years. These facilities are part of a global Phased Array Feeds. In so doing, they are paving the way coming out of 12 of these telescopes, is our tribute to effort to design and build ever-more sensitive instruments for the world’s largest radio telescope, the SKA. the pathfinder family as a whole, the people who have built to detect some of the faintest signals in the universe them and the people who are using them. The knowledge These facilities are now open to the community or going and grow new scientific and technical communities while and experience they’ve accumulated will guide us through through commissioning, and already they are providing benefiting society through cutting-edge R&D. -
Kraus Transcript.Pdf (118.8Kb)
INTERVIEW WITH DR. JOHN KRAUS AUGUST 20, 2002 Q. This is Robert Wagner. I’m at the home of Dr. John Kraus, who is Professor of Electrical Engineering and Astronomy Emeritus at Ohio State. And we’re recording this interview on August 20, 2002. Dr. Kraus, do you want to proceed and give us a little introduction to your work? A. Yes, I thought about your questions and I would like to say some things that relate to my impressions when I came to Ohio State in 1946. This was just after World War II. The students in those classes were some of the most serious and best students I ever had. It was a stimulating atmosphere. Within a few months of being at Ohio State, I made an invention in the basement of my home, the helical antenna, which soon became in use worldwide, and especially on satellites in space. It’s one of the main antennas that are used in space communication. The satellites that are up there and the space station and others use them. I had always been interested in astronomy and had made some experiments years ago to detect radio waves on the sun unsuccessfully. That was in 1932. Anyhow, the idea of building an array of these helical antennas a couple feet in diameter and ten feet long, putting up this array, 96 of them on the corner of the University farms that Dean Rummell, the Dean of Agriculture, said I could use, I thought was an exciting prospect because it would give Ohio State a radio telescope, one of the first built. -
Nobel Laureates
Nobel Laureates Over the centuries, the Academy has had a number of Nobel Prize winners amongst its members, many of whom were appointed Academicians before they received this prestigious international award. Pieter Zeeman (Physics, 1902) Lord Ernest Rutherford of Nelson (Chemistry, 1908) Guglielmo Marconi (Physics, 1909) Alexis Carrel (Physiology, 1912) Max von Laue (Physics, 1914) Max Planck (Physics, 1918) Niels Bohr (Physics, 1922) Sir Chandrasekhara Venkata Raman (Physics, 1930) Werner Heisenberg (Physics, 1932) Charles Scott Sherrington (Physiology or Medicine, 1932) Paul Dirac and Erwin Schrödinger (Physics, 1933) Thomas Hunt Morgan (Physiology or Medicine, 1933) Sir James Chadwick (Physics, 1935) Peter J.W. Debye (Chemistry, 1936) Victor Francis Hess (Physics, 1936) Corneille Jean François Heymans (Physiology or Medicine, 1938) Leopold Ruzicka (Chemistry, 1939) Edward Adelbert Doisy (Physiology or Medicine, 1943) George Charles de Hevesy (Chemistry, 1943) Otto Hahn (Chemistry, 1944) Sir Alexander Fleming (Physiology, 1945) Artturi Ilmari Virtanen (Chemistry, 1945) Sir Edward Victor Appleton (Physics, 1947) Bernardo Alberto Houssay (Physiology or Medicine, 1947) Arne Wilhelm Kaurin Tiselius (Chemistry, 1948) - 1 - Walter Rudolf Hess (Physiology or Medicine, 1949) Hideki Yukawa (Physics, 1949) Sir Cyril Norman Hinshelwood (Chemistry, 1956) Chen Ning Yang and Tsung-Dao Lee (Physics, 1957) Joshua Lederberg (Physiology, 1958) Severo Ochoa (Physiology or Medicine, 1959) Rudolf Mössbauer (Physics, 1961) Max F. Perutz (Chemistry, 1962) -
1 Case Study: Lise Meitner 1944 Nobel Prize in Chemistry Awarded
Case study: Lise Meitner 1944 Nobel Prize in Chemistry awarded to collaborator Otto Hahn After finishing her Ph.D. degree, Lise Mietner moved to Berlin, Germany. She came to study physics with Max Plank. This was where she met Otto Hahn. Hahn was working with famous chemist Emil Fischer when he met Lise Meitner. At that time, Fischer did not allow women in his laboratory. Instead, Hahn and Meitner created a workshop in the basement of the Chemical Institute just for Lise to work in. For 15 years Lise Mietner and Otto Hahn worked together. Then, in 1920, they decided to separate their research projects. During the years they worked together, they had an extremely close professional relationship but a far more formal personal one. Hahn respected her and her research but was unlikely to defend her when others questioned her ability, despite the fact that she was nominated for the Nobel Prize 13 times throughout her life. By colleagues and peers (including Albert Einstein) she was seen as far more capable and the principal figure in their collaborations. In 1934 Meitner recruited Hahn, along with Fritz Strassmann, to help her with her work on synthesizing “transuranic elements” (elements beyond uranium in the periodic table), as Meitner was more of a theorist than an experimental physicist. The rise of Nazi power in Germany brought great difficulties for Meitner due to her Jewish background. She could not present any of her own work, and Hahn could not mention her in presentations of work they completed together. She was forced to move to Sweden in 1938 to ensure that she could carry on working in some capacity.