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The Global Jet Structure of the Archetypical Quasar 3C 273
galaxies Article The Global Jet Structure of the Archetypical Quasar 3C 273 Kazunori Akiyama 1,2,3,*, Keiichi Asada 4, Vincent L. Fish 2 ID , Masanori Nakamura 4, Kazuhiro Hada 3 ID , Hiroshi Nagai 3 and Colin J. Lonsdale 2 1 National Radio Astronomy Observatory, 520 Edgemont Rd, Charlottesville, VA 22903, USA 2 Massachusetts Institute of Technology, Haystack Observatory, 99 Millstone Rd, Westford, MA 01886, USA; vfi[email protected] (V.L.F.); [email protected] (C.J.L.) 3 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; [email protected] (K.H.); [email protected] (H.N.) 4 Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan; [email protected] (K.A.); [email protected] (M.N.) * Correspondence: [email protected] Received: 16 September 2017; Accepted: 8 January 2018; Published: 24 January 2018 Abstract: A key question in the formation of the relativistic jets in active galactic nuclei (AGNs) is the collimation process of their energetic plasma flow launched from the central supermassive black hole (SMBH). Recent observations of nearby low-luminosity radio galaxies exhibit a clear picture of parabolic collimation inside the Bondi accretion radius. On the other hand, little is known of the observational properties of jet collimation in more luminous quasars, where the accretion flow may be significantly different due to much higher accretion rates. In this paper, we present preliminary results of multi-frequency observations of the archetypal quasar 3C 273 with the Very Long Baseline Array (VLBA) at 1.4, 15, and 43 GHz, and Multi-Element Radio Linked Interferometer Network (MERLIN) at 1.6 GHz. -
EDGES Memo #054
EDGES MEMO #054 MASSACHUSETTS INSTITUTE OF TECHNOLOGY HAYSTACK OBSERVATORY WESTFORD, MASSACHUSETTS 01886 December 1, 2009 Telephone: 781-981-5407 Fax: 781-981-0590 To: EDGES Group From: Alan E.E. Rogers Subject: Meteor scatter rates Since all the World’s designated radio quiet zones are les than 2000 km from strong radio transmitters they are subject to RFI from meteor scatter. The key parameters of meteor scatter are poorly determined. For example, theory suggests that the radar cross-section (RCS) should decrease by 20 dB per decade from head echoes but measurements typically have an even faster decline with frequency. The frequency range for significant scatter and the range of concern to radio astronomy is about 50 to 300 MHz. Some papers claim that 1012 meteors enter the Earth’s atmosphere each day while others suggest a number more like 109. In practice we observed a rate of about 1 per minute when located in a canyon (see memo #52) with sky coverage limited to elevations greater than about 25 degrees. Based on the geometry of Figure 1 this corresponds to a worldwide rate of about 107/day. Figure 2 shows the estimated burst rate as a function of elevation cut-off angle. This very sharp curve shows the advantage of limiting the low elevation response of the antenna or using the terrain to limit the elevation angle. Potential locations for EDGES are on route 205 in the canyon just before 205 enters the Catlow Valley, Oregon or about 1km West of route 205 on Skull creek road. 1 h R To solve: theta=acos( ( (R+ h)*(R+ h)+ R*R-r*r) / (2*(R+ h)*R)) a 1 b -2*R*cos(elev+90) c = -(R+h)*(R+h)+R*R r = ((- b+sqrt(b*b-4*a*c) / (2*a) ; R earth radius = 6357 km r = region where meteors form ions ,-..J 100 km Figure 1. -
Square Kilometre Array Computational Challenges
Square Kilometre Array Computational Challenges Paul Alexander Paul Alexander SKA Computational Challenges What is the Square Kilometre Array (SKA) • Next Generation radio telescope – compared to best current instruments it is ... E-MERLIN • ~100 times sensitivity • ~ 106 times faster imaging the sky • More than 5 square km of collecting area on sizes 3000km eVLA 27 27m dishes Longest baseline 30km GMRT 30 45m dishes Longest baseline 35 km Paul Alexander SKA Computational Challenges What is the Square Kilometre Array (SKA) • Next Generation radio telescope – compared to best current instruments it is ... • ~100 times sensitivity • ~ 106 times faster imaging the sky • More than 5 square km of collecting area on sizes 3000km • Will address some of the key problems of astrophysics and cosmology (and physics) • Builds on techniques developed in Cambridge • It is an interferometer • Uses innovative technologies... • Major ICT project • Need performance at low unit cost Paul Alexander SKA Computational Challenges Dishes Paul Alexander SKA Computational Challenges Phased Aperture array Paul Alexander SKA Computational Challenges also a Continental sized Radio Telescope • Need a radio-quiet site • Very low population density • Large amount of space • Possible sites (decision 2012) • Western Australia • Karoo Desert RSA Paul Alexander SKA Computational Challenges Sensitivity comparison 12,000 Sensitivity Comparison 10,000 1 - K 2 8,000 SKA2 6,000 SKA2 SKA1 MeerKAT LOFAR ASKAP 4,000 Sensitivity: Aeff/Tsys m Sensitivity:Aeff/Tsys eVLA SKA1 2,000 -
CASKAR: a CASPER Concept for the SKA Phase 1 Signal Processing Sub-System
CASKAR: A CASPER concept for the SKA phase 1 Signal Processing Sub-system Francois Kapp, SKA SA Outline • Background • Technical – Architecture – Power • Cost • Schedule • Challenges/Risks • Conclusions Background CASPER Technology MeerKAT Who is CASPER? • Berkeley Wireless Research Center • Nancay Observatory • UC Berkeley Radio Astronomy Lab • Oxford University Astrophysics • UC Berkeley Space Sciences Lab • Metsähovi Radio Observatory, Helsinki University of • Karoo Array Telescope / SKA - SA Technology • NRAO - Green Bank • New Jersey Institute of Technology • NRAO - Socorro • West Virginia University Department of Physics • Allen Telescope Array • University of Iowa Department of Astronomy and • MIT Haystack Observatory Physics • Harvard-Smithsonian Center for Astrophysics • Ohio State University Electroscience Lab • Caltech • Hong Kong University Department of Electrical and Electronic Engineering • Cornell University • Hartebeesthoek Radio Astronomy Observatory • NAIC - Arecibo Observatory • INAF - Istituto di Radioastronomia, Northern Cross • UC Berkeley - Leuschner Observatory Radiotelescope • Giant Metrewave Radio Telescope • University of Manchester, Jodrell Bank Centre for • Institute of Astronomy and Astrophysics, Academia Sinica Astrophysics • National Astronomical Observatories, Chinese Academy of • Submillimeter Array Sciences • NRAO - Tucson / University of Arizona Department of • CSIRO - Australia Telescope National Facility Astronomy • Parkes Observatory • Center for Astrophysics and Supercomputing, Swinburne University -
Next Generation Radio Arrays
NextNext GenerationGeneration RadioRadio ArraysArrays Dr.Dr. FrankFrank D.D. LindLind MITMIT HaystackHaystack ObservatoryObservatory (with acknowledgement to my colleagues who contribute to these efforts...) [McKay-Bukowski, et al., 2014] contact info : Frank D. Lind MIT Haystack Observatory Route 40 Westford MA, 01886 email - [email protected] DeepDeep MemoryMemory Solid state memory capacity will exceed our data storage requirements. Deep memory instruments will become possible. Store all data from every element for the life of a radio array... Intel + Micron 3D Flash Intel XPoint memory Keon Jae Lee of the Korea Advanced Institute of Science and Technology (KAIST) ConnectedConnected WorldWorld Wireless networks will be global and even replace the wires. Disconnected, self networking, and software realized instrumentation Sparse global radio arrays, deployable dense arrays, and ad-hoc arrays DisappearingDisappearing SensorsSensors Integration will become extreme and include quantum referenced sensors Receivers in connectors, cloud computers on a chip, really good clocks Energy harvesting and low power near field wireless data Self coherent arrays, personal passive radar, the ionosphere as a sensor Deployable Low Power Radio Platforms Instruments in ~ 10W power envelopes. Future systems will use ~ 1W of power total. Zero infrastructure radio science instrumentation Software radio and radar technology Solar and battery power Low power computing for data acquisition Intelligent control software Mahali Array (during build out) Deep -
10. Scientific Programme 10.1
10. SCIENTIFIC PROGRAMME 10.1. OVERVIEW (a) Invited Discourses Plenary Hall B 18:00-19:30 ID1 “The Zoo of Galaxies” Karen Masters, University of Portsmouth, UK Monday, 20 August ID2 “Supernovae, the Accelerating Cosmos, and Dark Energy” Brian Schmidt, ANU, Australia Wednesday, 22 August ID3 “The Herschel View of Star Formation” Philippe André, CEA Saclay, France Wednesday, 29 August ID4 “Past, Present and Future of Chinese Astronomy” Cheng Fang, Nanjing University, China Nanjing Thursday, 30 August (b) Plenary Symposium Review Talks Plenary Hall B (B) 8:30-10:00 Or Rooms 309A+B (3) IAUS 288 Astrophysics from Antarctica John Storey (3) Mon. 20 IAUS 289 The Cosmic Distance Scale: Past, Present and Future Wendy Freedman (3) Mon. 27 IAUS 290 Probing General Relativity using Accreting Black Holes Andy Fabian (B) Wed. 22 IAUS 291 Pulsars are Cool – seriously Scott Ransom (3) Thu. 23 Magnetars: neutron stars with magnetic storms Nanda Rea (3) Thu. 23 Probing Gravitation with Pulsars Michael Kremer (3) Thu. 23 IAUS 292 From Gas to Stars over Cosmic Time Mordacai-Mark Mac Low (B) Tue. 21 IAUS 293 The Kepler Mission: NASA’s ExoEarth Census Natalie Batalha (3) Tue. 28 IAUS 294 The Origin and Evolution of Cosmic Magnetism Bryan Gaensler (B) Wed. 29 IAUS 295 Black Holes in Galaxies John Kormendy (B) Thu. 30 (c) Symposia - Week 1 IAUS 288 Astrophysics from Antartica IAUS 290 Accretion on all scales IAUS 291 Neutron Stars and Pulsars IAUS 292 Molecular gas, Dust, and Star Formation in Galaxies (d) Symposia –Week 2 IAUS 289 Advancing the Physics of Cosmic -
Detection Statistics of the Radioastron AGN Survey
Available online at www.sciencedirect.com ScienceDirect Advances in Space Research 65 (2020) 705–711 www.elsevier.com/locate/asr Detection statistics of the RadioAstron AGN survey Y.Y. Kovalev a,b,c,⇑, N.S. Kardashev a,†, K.V. Sokolovsky a,d,e, P.A. Voitsik a,T.Anf, J.M. Anderson g,h, A.S. Andrianov a, V.Yu. Avdeev a, N. Bartel i, H.E. Bignall j, M.S. Burgin a, P.G. Edwards k, S.P. Ellingsen l, S. Frey m, C. Garcı´a-Miro´ n, M.P. Gawron´ski o, F.D. Ghigo p, T. Ghosh p,q, G. Giovannini r,s, I.A. Girin a, M. Giroletti r, L.I. Gurvits t,u, D.L. Jauncey k,v, S. Horiuchi w, D.V. Ivanov x, M.A. Kharinov x, J.Y. Koay y, V.I. Kostenko a, A.V. Kovalenko aa, Yu.A. Kovalev a, E.V. Kravchenko r,a, M. Kunert-Bajraszewska o, A.M. Kutkin a,z, S.F. Likhachev a, M.M. Lisakov c,a, I.D. Litovchenko a, J.N. McCallum l, A. Melis ab, A.E. Melnikov x, C. Migoni ab, D.G. Nair t, I.N. Pashchenko a, C.J. Phillips k, A. Polatidis z, A.B. Pushkarev a,ad, J.F.H. Quick ae, I.A. Rakhimov x, C. Reynolds j, J.R. Rizzo af, A.G. Rudnitskiy a, T. Savolainen ag,ah,c, N.N. Shakhvorostova a, M.V. Shatskaya a, Z.-Q. Shen f,ac, M.A. Shchurov a, R.C. Vermeulen z, P. de Vicente ai, P. -
Real-Time High Volume Data Transfer and Processing for E-VLBI
Real-time high volume data transfer and processing for e-VLBI Yasuhiro Koyama, Tetsuro Kondo, Hiroshi Takeuchi, Moritaka Kimura (Kashima Space Research Center, NICT, Japan) and Masaki Hirabaru (New Generation Network Research Center, NICT, Japan) OutlineOutline What is e-VLBI? Why e-VLBI is necessary? How? – K5 VLBI System ~ Standardization – Network Test Experiments – June 2004 : Near-Realtime UT1 Estimation – January 2005 : Realtime Processing Demo Future Plan Traditional VLBI The Very-Long Baseline Interferometry (VLBI) Technique (with traditional data recording) The Global VLBI Array (up to ~20 stations can be used simultaneously) WhatWhat isis ee--VVLBI?LBI? VLBI=Very Long Baseline Interferometry Correlator Radio Telescope Network Correlator Radio Telescope Shipping Data Media e-VLBI (Tapes/Disks) Conventional VLBI VLBIVLBI ApplicationsApplications Geophysics and Plate Tectonics Kashima-Kauai鹿島-ハワイの基線長変化 Baseline Length -63.5 ± 0.5 mm/year 400 200 0 -200 基線長(mm) -400 5400km 5400km Fairbanksアラスカ 1984 1986 1988 1990 1992 1994 Fairbanks-Kauaiアラスカ-ハワイの基線長変化年 Baseline Length 4700km 4700km -46.1 ± 0.3 mm/year Kashima鹿島 400 5700km 200 Kauaiハワイ 0 -200 基線長(mm) -400 1984 1986 1988 1990 1992 1994 Kashima-Fairbanks鹿島-アラスカの基線長変化年 Baseline Length 1.3 ± 0.5 mm/year 400 200 0 -200 基線長(mm) -400 1984 1986 1988 1990 1992 1994 年 VLBIVLBI ApplicationsApplications (2)(2) Radio Astronomy : High Resolution Imaging, Astro-dynamics Reference Frame : Celestial / Terrestrial Reference Frame Earth Orientation Parameters, Dynamics of Earth’s Inner Core -
Istituto Di Radioastronomia Inaf
ISTITUTO DI RADIOASTRONOMIA INAF STATUS REPORT October 2007 http://www.ira.inaf.it/ Chapter 1. STRUCTURE AND ORGANIZATION The Istituto di Radioastronomia (IRA) is presently the only INAF structure with divisions distributed over the national territory. Such an organization came about because IRA was originally a part of the National Council of Research (CNR), which imposed the first of its own reforms in 2001. The transition from CNR to INAF began in 2004 and was completed on January 1st , 2005. The Institute has its headquarters in Bologna in the CNR campus area, and two divisions in Firenze and Noto. The Medicina station belongs to the Bologna headquarters. A fourth division is foreseen in Cagliari at the Sardinia Radiotelescope site. The IRA operates 3 radio telescopes: the Northern Cross Radio Telescope (Medicina), and two 32-m dishes (Medicina and Noto), which are used primarily for Very Long Baseline Interferometry (VLBI) observations. The IRA leads the construction of the Sardinia Radio Telescope (SRT), a 64-m dish of new design. This is one of the INAF large projects nowadays. The aims of the Institute comprise: - the pursuit of excellence in many research areas ranging from observational radio astronomy, both galactic and extragalactic, to cosmology, to geodesy and Earth studies; - the design and management of the Italian radio astronomical facilities; - the design and fabrication of instrumentation operating in bands from radio to infrared and visible. Main activities of the various sites include: Bologna: The headquarters are responsible for the institute management and act as interface with the INAF central headquarters in Roma. Much of the astronomical research is done in Bologna, with major areas in cosmology, extragalactic astrophysics, star formation and geodesy. -
Fact Sheet Fact Sheet
FactFact sheet sheet What is the SKA? The Square Kilometre Array (SKA) is a next-generation radio telescope that will be vastly more sensitive than the best present-day instruments. It will give astronomers remarkable insights into the formation of the early Universe, including the emergence of the first stars, galaxies and other structures. This will shed light on the birth, and eventual death, of the cosmos. The SKA will require new technology and progress in Why build the SKA? fundamental engineering in fields such as information and communication technology, high performance computing In order to answer some fundamental questions about the and production manufacturing techniques. It will comprise origin and evolution of the Universe, a more sensitive radio a vast array of antennas, arranged in clusters to be spread telescope is needed that can detect the very weak signals over 3000 kilometres or more. The antennas will be linked coming from the edge of the cosmos. A telescope such as the electronically to form one enormous telescope. The SKA will be able to “see” distant objects in the very young combination of unprecedented collecting area, versatility Universe and provide answers to questions such as the and sensitivity will make the SKA the world’s premier imaging emergence of the first stars, galaxies and other structures. and survey telescope over a wide range of radio frequencies, Because the speed of light is finite and the size of the Universe producing the sharpest pictures of the sky of any telescope. is so large, telescopes are effectively time machines, enabling astronomers to look into the past and study the Universe as it The SKA will: was billions of years ago. -
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. -
The Mid-Frequency Square Kilometre Array Phase Synchronisation System
Publications of the Astronomical Society of Australia (PASA) doi: 10.1017/pas.2018.xxx. The Mid-Frequency Square Kilometre Array Phase Synchronisation System S. W. Schediwy1,2,∗, D. R. Gozzard1,2, C. Gravestock1, S. Stobie1, R. Whitaker3, J. A. Malan4, P. Boven5 and K. Grainge3 1International Centre for Radio Astronomy Research, School of Physics, Mathematics & Computing, The University of Western Australia, Perth, WA 6009, Australia 2Department of Physics, School of Physics, Mathematics & Computing, The University of Western Australia, Perth, WA 6009, Australia 3Jodrell Bank Centre for Astrophysics, School of Physics & Astronomy, The University of Manchester, Manchester, M13 9PL, UK 4Square Kilometre Array South Africa, The South African Radio Astronomy Observatory, Pinelands 7405, South Africa 5Joint Institute for VLBI ERIC (JIVE), Dwingeloo, The Netherlands Abstract This paper describes the technical details and practical implementation of the phase synchronisation system selected for use by the Mid-Frequency Square Kilometre Array (SKA). Over a four-year period, the system has been tested on metropolitan fibre-optic networks, on long-haul overhead fibre at the South African SKA site, and on existing telescopes in Australia to verify its functional performance. The tests have shown that the system exceeds the 1-second SKA coherence loss requirement by a factor of 2560, the 60-second coherence loss requirement by a factor of 239, and the 10-minute phase drift requirement by almost five orders-of-magnitude. The paper also reports on tests showing that the system can operate within specification over all the required operating conditions, including maximum fibre link distance, temperature range, temperature gradient, relative humidity, wind speed, seismic resilience, electromagnetic compliance, frequency offset, and other operational requirements.