NRAO Enews Volume 12, Issue 5 • 13 June 2019

Total Page:16

File Type:pdf, Size:1020Kb

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. There was significant demand for the time made available on space observatories through inter-observatory agreements, and fourteen proposals requesting time on HST, Swift or Chandra (together with AUI/NRAO telescope time) were submitted. The proposals were reviewed for scientific merit by nine Science Review Panels (SRPs) and for technical feasibility by NRAO staff. These reviews were completed in February – March 2019 and then considered by the Time Allocation Committee (TAC) (https://science.nrao.edu/observing/proposal-types/time-allocation-committee) at a face-to-face meeting on 24-25 April 2019 in Green Bank, West Virginia. The TAC – comprising the 9 SRP chairs – was charged with recommending a science program for Semester 2019B to the Observatory Director. The recommended program was reviewed and approved on 8 May 2019. Proposals submitted to the GBO were assessed through the same process. Fifty eight proposals for the GBT were received for the 19B Semester, including one large and four triggered proposals. The oversubscription rate is 2.5 and the proposal pressure is 2.2. For information on proposals for GBT observations see the GBO website (https://greenbankobservatory.org/science/gbt-observers/proposals/past-proposal-calls/2019b-results/) . A disposition letter was sent to the Principal Investigator and Co-Investigators of each proposal on 16 May 2019 and a TAC report (https://science.nrao.edu/observing/proposal-types/tac-reports/19b-tac-report) containing information for proposers and observers, including statistics and telescope pressure plots, was released the same day. The approved science program (https://science.nrao.edu/science/science-program) for the VLA and the VLBA has been posted to the NRAO science website (http://science.nrao.edu/) . The authors, title, abstract, and scheduled hours for each approved proposal can be accessed from the Proposal Finder Tool (http://library.nrao.edu/proposals) . The Student Observing Support program continues to be available for NRAO observing programs and we encourage Principal Investigators of highly ranked VLA and VLBA proposals to consider applying for support. The NRAO welcomes community feedback on the proposal review and time allocation process (https://science.nrao.edu/observing/proposal-types/proposal-review-system) . Please provide such feedback via the Proposal Review department of the NRAO Helpdesk (http://help.nrao.edu/) . Announcement of Opportunity – Extra­Large Proposals Lewis Ball NRAO and GBO will consider submissions of Extra-Large observing proposals (X-proposals for short) at the upcoming 1 August proposal submission deadline. This opportunity is open for observers seeking to use the VLA, VLBA and / or GBT. Extra-Large proposals will be defined as those requesting a total of more than 1000 hours of telescope time and / or extending over four or more observing semesters. Note that the earliest that successful Extra-Large projects could be scheduled is the start of Semester 2020B in August 2020. The opportunity to submit Extra-Large proposals will likely not be repeated for at least three years. Regular and Large proposals continue to be encouraged for Semesters 2020A and beyond. At least 50% of open skies science time on each of the VLA, VLBA and GBT will continue to be made available for Regular and Large proposals from Semester 2020B. (The maximum amount of time that can be requested through a Large proposal will be capped at 1000 hours starting from Semester 2020B.) To be accepted, Extra-Large proposals will be expected to demonstrate outstanding science impact, a high level of scientific and technical readiness, and excellent legacy science value (potential to generate high science impact from community use of archival data and data products.) The capabilities available for Extra-Large Proposals will be restricted to a subset of general observing capabilities – Shared Risk Observing and Resident Shared Risk Observing capabilities will not be available for Extra-Large proposals, and high-frequency bands (12 GHz and above) are likely to be excluded or severely restricted for all three telescopes because of scheduling difficulty and the limited available time with suitable observing conditions. Specific capabilities that will not be available for Extra-Large proposals are: For the VLA – pulsar modes, phased array, subarrays, mixed 3/8-bit samplers, moving sources (including Solar and planetary observing), and On-The-Fly mosaicking; in addition, observing time at 12 GHz and above will be restricted according to the expected availability of suitable observing conditions; For the VLBA – moving sources and 3mm observing; in addition, observing time in the 2cm, 1cm, and 7mm bands will be restricted according to expected availability of suitable observing conditions; For the GBT – monitoring and fixed time observations, observations with any weather restrictions (typically above 8 GHz). Extra-Large Proposals requiring fixed observing dates will not be supported for any telescope. Additional band, configuration, response time and cadence restrictions may also apply for each telescope. The definitive list of capabilities excluded from Extra-Large proposals will be provided in the Call for Proposals that will be released on 2 July 2019. The scientific review process for Extra-Large proposals will be different from the normal NRAO Science Review Panel (SRP) / Time Allocation Committee process. The Science Review Panels will assess the scientific potential of each Extra-Large proposal in their science area, providing comments and a coarse grading. A new X-Proposal Science Assessment Committee (XSAC) appointed by the NRAO and GBO Directors will assess the Extra-Large proposals for their scientific merit and likely legacy science value, taking into account the initial assessments from the SRPs. Observatory staff will assess each proposal for technical readiness, and the final selection of proposals will involve a face to face scientific, technical and operations readiness review in Spring 2020. Preference will be given to proposals which demonstrate substantial engagement with astronomers at U.S. institutions. Preference may be given to proposals with lower requirements for observatory support, and lower operational impact. The progress of Extra-Large projects that are accepted will be monitored through NRAO Program Management Department processes. The announcement of successful Extra-Large proposals is anticipated to occur in July 2020. The deadline for submissions will be 1 August 2019, the same as for Semester 2020A regular and large proposals. Submission of Extra-Large proposals will be via the usual NRAO Proposal Submission Tool (PST) with the same 10-page limit for the Scientific Justification. Extra-Large proposals will be required to also submit (or provide a link to) additional material addressing the following issues: The data management and delivery plan, including computing resource requirements; A set of major project milestones and schedule; The team resources (including plans for resident scientists at the Observatory). Proposers are also encouraged to address the following: The demonstrated feasibility of the project; Any special requirements (such as scheduling, calibration, scanning, data processing); Engagement of U.S. astronomical community; For the GBT, an observing plan. The ability of the proposing team to execute the data management plan, as well as the feasibility for NRAO to accommodate any requests made of it in the data management plan, will be evaluated as part of the review process Information that assists Observatory staff to assess likely operational and NRAO/GBO support implications will be welcomed as part of the additional material. This will be the focus of the final face to face technical and operations readiness reviews with the highest ranked proposal teams. More details will be provided in the formal call for proposals on 2 July
Recommended publications
  • 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.
    [Show full text]
  • Astro2020 APC White Paper Panel on Radio
    Astro2020 APC White Paper Panel on Radio, Millimeter, and Submillimeter Observations from the Ground The Case for a Fully Funded Green Bank Telescope Brief Description [350 character limit]: The NSF has reduced its funding for peer-reviewed use on the GBT to ~3900 hours/year, 60% of available science time. This greatly increases the telescope pressure & fragments the schedule, making it very difficult to allocate time for even the highest rated projects planned for the next decade. Here we seek funding for 1500 more hours annually. Principal Author: K. O’Neil (Green Bank Observatory; [email protected]) Co-authors: Felix J Lockman (Green Bank Observatory), Filippo D'Ammando (INAF-IRA Bologna), Will Armentrout (Green Bank Observatory), Shami Chatterjee (Cornell University), Jim Cordes (Cornell University), Martin Cordiner (NASA GSFC), David Frayer (Green Bank Observatory), Luke Zoltan Kelley (Northwestern University), Natalia Lewandowska (West Virginia University), Duncan Lorimer (WVU), Brian Mason (NRAO), Maura McLaughlin (West Virginia University), Tony Mroczkowski (European Southern Observatory), Hooshang Nayyeri (UC Irvine), Eric Perlman (Florida Institute of Technology), Bindu Rani (NASA Goddard Space Flight Center), Dominik Riechers (Cornell University), Martin Sahlan (Uppsala University), Ian Stephens (CfA/SAO), Patrick Taylor (Lunar and Planetary Institute), Francisco Villaescusa- Navarro (Center for Computational Astrophysics, Flatiron Institute) Endosers: Esteban D. Araya (Western Illinois University), Hector Arce (Yale
    [Show full text]
  • 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.
    [Show full text]
  • 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
    [Show full text]
  • 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
    [Show full text]
  • 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
    [Show full text]
  • Longterm MWL Behavior of 1ES1959+650
    Fakultät Physik – Experimentelle Physik 5 Long-term observations of the TeV blazar 1ES 1959+650 Temporal and spectral behavior in the multi-wavelength context Dissertation zur Erlangung des akademischen Grades eines Doktors der Naturwissenschaften (Dr. rer. nat.) vorgelegt von Dipl.-Phys. Michael Backes Dezember 2011 Contents 1 Introduction 1 2 Brief Introduction to Astroparticle Physics 3 2.1 ChargedCosmicRays .............................. 4 2.1.1 CompositionofCosmicRays . 4 2.1.2 EnergySpectrumofCosmicRays. 5 2.1.3 Sources of Cosmic Rays up to 1018 eV................ 6 ∼ 2.1.4 Sources of Cosmic Rays above 1018 eV................ 8 ∼ 2.2 AstrophysicalNeutrinos . ... 12 2.3 PhotonsfromOuterSpace. 13 2.3.1 Leptonic Processes: Connecting Low and High Energy Photons . 13 2.3.2 Hadronic Processes: Connecting Photons, Protons, and Neutrinos . 16 2.4 ActiveGalacticNuclei . 16 2.4.1 Blazars .................................. 17 2.4.2 EmissionModels ............................. 19 2.4.3 BinaryBlackHolesinAGN . 20 3 Instruments for Multi-Wavelength Astronomy 25 3.1 RadioandMicrowave .............................. 25 3.1.1 Single-DishInstruments . 25 3.1.2 Interferometers .............................. 26 3.1.3 Satellites ................................. 27 3.2 Infrared ...................................... 27 3.3 Optical ...................................... 28 3.3.1 Satellite-Born............................... 28 3.3.2 Ground-Based .............................. 28 3.4 Ultraviolet..................................... 29 3.5 X-Rays .....................................
    [Show full text]
  • 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.
    [Show full text]
  • 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.
    [Show full text]
  • 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.
    [Show full text]
  • Selection of Radio Astronomical Observation Sites and Its Dependence on Human Generated RFI
    RAA 2014 Vol. 14 No. 2, 241–248 doi: 10.1088/1674–4527/14/2/012 Research in http://www.raa-journal.org http://www.iop.org/journals/raa Astronomy and Astrophysics Selection of radio astronomical observation sites and its dependence on human generated RFI Roslan Umar1;2, Zamri Zainal Abidin1, Zainol Abidin Ibrahim1, Zulfazli Rosli1 and Noorkhallaf Noorazlan1 1 Department of Physics, University of Malaya, 50603, Kuala Lumpur, Malaysia; [email protected] 2 Astronomy Unit, Universiti Sultan Zainal Abidin, 21300, Kuala Terengganu, Malaysia Received 2013 June 7; accepted 2013 October 23 Abstract We investigate the influence of population density on radio-frequency inter- ference (RFI) affecting radio astronomy. We use a new method to quantify the thresh- old of population density in order to determine the most suitable lower limit for site selection of a radio quiet zone (RQZ). We found that there is a certain trend in the population density-RFI graph that increases rapidly at lower values and slows down to almost flat at higher values. We use this trend to identify the thresholds for pop- ulation density that produce RFI. Using this method we found that, for frequencies up to 2.8 GHz, low, medium and high population densities affecting radio astronomy are below 150 ppl km¡2, between 150 ppl km¡2 and 5125 ppl km¡2, and above 5125 ppl km¡2 respectively. We also investigate the effect of population density on the environment of RFI in three astronomical windows, namely the deuterium, hydro- gen and hydroxyl lines. We find that a polynomial fitting to the population density produces a similar trend, giving similar thresholds for the effect of population density.
    [Show full text]
  • NATIONAL SCIENCE FOUNDATION Notice Of
    This document is scheduled to be published in the Federal Register on 11/08/2017 and available online at h ttps://federalregister.gov/d/2017-24322, and on FDsys.gov 7555-01-P NATIONAL SCIENCE FOUNDATION Notice of Availability and Notice of Public Meeting for the Draft Environmental Impact Statement (DEIS) for the Green Bank Observatory, Green Bank, West Virginia AGENCY: National Science Foundation. ACTION: Notice of Availability and Notice of Public Meeting. SUMMARY: The National Science Foundation (NSF) has made available for public review and comment the Draft Environmental Impact Statement (DEIS) for Green Bank Observatory. This DEIS has been prepared for the National Science Foundation (NSF) to evaluate the potential environmental impacts resulting from proposed operational changes due to funding constraints for the Green Bank Observatory in Green Bank, West Virginia. The DEIS was prepared in compliance with the National Environmental Policy Act of 1969. Consultation under Section 106 of the National Historic Preservation Act (NHPA) is being conducted concurrent with the NEPA process. DATES: NSF will accept comments on the DEIS for 60 days following publication of this Notice of Availability; an additional 15 days are being provided beyond the standard 45-day review period to allow for the holidays). Comments may be submitted verbally during the public meeting scheduled for November 30, 2017 (see details in SUPPLEMENTARY INFORMATION) or in writing until January 8th, 2018. Substantive comments will be addressed in a Final Environmental
    [Show full text]