Radio 101: Everything you ever wanted to know about the basics of radio astronomy, but were afraid to ask

Organizers: Chat Hull, Statia Luszcz-Cook, Amber Bauermeister, Peter Williams, Jonathan Pober, Geoff Bower, Carl Heiles

When: Tuesdays from 2-3:30 p.m.

Where: 544 Campbell

CCN: 06415 (sign up for S/U)

Contact: radio101@lists.berkeley.edu (organizers); radio101_f10@lists.berkeley.edu (whole class)

You can skip to the reading for this week or check out the course notes on AstroBaki.

For next time, here are some notes on the course.

Course philosophy

Radio 101 is a seminar-style course on the basics of radio astronomy. The class is designed to appeal to beginners interested in learning what radio astronomy can do and how it works, as well as to more “seasoned” students wanting to develop a stronger understanding of the basics.

Course logistics

  • Each class will cover one or two fundamental topics in radio astronomy.
  • Readings will be provided ahead of time. They are designed to be short enough for everyone to read, thorough enough to discuss for a full class period, and basic enough for a neophyte radio astronomy student to understand.
  • Everyone should read the suggested material before class.
  • Class participants (students, postdocs, faculty) will sign up to present the material covered in the week's readings.
  • Speakers can and should seek out the organizers when questions come up during talk preparation.
  • There will be two 25-minute talks per class, followed by discussion.
  • Experts in the day's topics are encouraged to attend.
  • Suggestions and interjections from the audience should be encouraged when speakers get stumped, though these interjections should be helpful, not hostile.
  • Board work is encouraged; slides with pictures only are okay.
  • Suggestions for improvements are welcome! In particular, if you know of a fabulous reading that clearly and concisely describes a fundamental topic, or think we have left something critical out of the syllabus, please let us know.

Resources

  • Note: many of these resources are on reserve in the Physics & Astronomy library. Click here to go to the “Course Reserves” page on OskiCat, and then type in “Astronomy 250” and click on the “Bower, G.” option to find the reserved books. Others are available online, and will be linked to this wiki page. There are also several copies of these resources in the department (you should not have to buy books unless you want to!)

Single Dish

Interferometry

Other

Discussion outlines on AstroBaki

An outline of each discussion can be found in the Radio 101 section of Aaron Parsons's AstroBaki wiki.

Course outline

8/31Science

  1. Course introduction
  2. Why is radio awesome?! Discussion of relevant science and radiative processes from your five organizers.
  3. Course logistics

9/7Single-dish basics

  1. Radio basics and reflector antennas (Katey Alatalo)
  2. Practicalities and Performance Parameters (Amber Bauermeister)

9/14Single-dish signal path & calibration

  1. Signal path (Chat Hull)
  2. Calibration (Katie Silverio)

9/21Single Dish Imaging, Spectral Line

  1. Single Dish Imaging (Therese Jones)
  2. Spectral line basics (James McBride)

9/28Fourier Transforms
Combined lecture: (Keaton Burns and Terry Filiba)

10/5Polarization

  1. Characterization of Polarization (Chat Hull)
  2. Measurement of Polarization (Nicholas McConnell)

10/12Interferometry I

  1. 2-element interferometer (Karto Keating)
  2. Interferometer response (Jonnie Pober)

10/19Interferometry II

  1. Basic properties of synthesis arrays (Peter Williams)
  2. Aperture Synthesis (Toki Suzuki)

10/26Interferometry III

  1. Correlators & phase switching (Terry Filiba)
  2. Calibration (Katey Alatalo)

11/2Imaging I

  1. Dirty map and weighting (Jonnie Pober)
  2. Deconvolution and MFS (Peter Williams)

11/9Imaging II: Imaging Errors & Data Editing
Combined lecture: (Karto Keating and Casey Law)

11/16Imaging III: Wide-field Imaging

  1. Non-coplanar imaging (Statia Cook)
  2. Mosaicking (Steve Croft)

11/18Imaging IV: Spectral Line and Polarization Considerations

  1. Spectral Line (Statia Cook)
  2. Polarization (Amber Bauermeister)

11/30Berkeley radio astronomy; wrap-up

  1. Radio astronomy in the Berkeley community (presenters & audience)
  2. Topic clarification, wrap-up (audience)

Detailed topic list, with associated readings

8/31Science

  1. Course introduction
  2. Introduction to science and radiative processes relevant to the radio astronomy
    • Statia: Molecular mysteries in the Solar System
      • Why do rotational lines appear in the millimeter regime?
      • Small scale: planets, comets, solar system molecular-line studies
      • Relevant emission mechanisms: molecular rotational lines
    • Chat: Molecular mysteries in the Galaxy
      • Small-to-medium scale: protostars, dense cores, molecular clouds, disks, CO and other molecules
      • Relevant emission mechanisms: molecular rotational lines, thermal dust emission
    • Amber: Molecular and atomic mysteries of intra- and extragalactic nature
      • Galactic and extragalactic HI, high-velocity clouds
      • Relevant emission mechanisms: molecular rotational lines, 21 cm radiation
    • Peter: Transient galactic mysteries
      • Galactic radio sources & transients: pulsars, X-ray binaries, Galactic synchrotron background, Bremsstrahlung in HII regions, supernova remnants, masers, microquasars, scintillation
      • Relevant emission mechanisms: Bremsstrahlung, synchrotron
    • Jonnie: Extragalactic and cosmological mysteries
      • Cosmology: quasars and radio galaxies, galaxy clusters (Sunyaev-Zel'dovich effect), cosmic microwave background, epoch of reionization
      • Relevant emission mechanisms: synchrotron, inverse Compton scattering, thermal blackbody, 21 cm radiation
9/7 --- Single-dish basics
  1. Radio basics and reflector antennas
    • Readings for Everyone:
    • Additional Readings for Presenters:
      • Kraus (1986 ed.), sec. 6-24 = 15 skimmable pages
    • Specific Topics to be Covered:
      • Specific intensity, flux density, brightness temperature
      • Antennas as abstract power collectors: A_eff, Jy/K, T_ant
      • Antenna architecture zoo (in Kraus reading)
  2. Practicalities and Performance Parameters
9/14 --- Single-dish signal path & calibration
  1. Signal path
    • Readings for Everyone:
    • Additional Readings for Presenters:
    • Specific Topics to be Covered:
      • Feed, polarizer, OMT, mixer, LNA, filters
      • Heterodyning
      • Back-ends: detectors (samplers come later)
      • Focal plane arrays (inc. coma, abberations)
      • Bolometer arrays
  2. Calibration
    • Readings for Everyone:
    • Additional Readings for Presenters:
      • CARMA calibration example 1: Click here for a high-quality CARMA observation, exhibiting T_sys vs. time, gain amplitude vs. time, and bandpass amplitude vs. channel. There is also phase information, which will be applicable once we get to interferometry.
      • CARMA calibration example 2: Click here for a CARMA observation that would have been good had it not been for a baseline error, which caused huge phase slopes across the bandpass. Appropriate for interferometry.
      • CARMA calibration example 3: Click here for your run-of-the-mill failed CARMA observation (failed due to weather). The data are still useable, however.
      • Optional: Carl suggests this paper on bandpass. The introduction (= 1 p.) has a good description of least-squares frequency switching, which separates the IF gain from the RF gain.
      • Optional: Carl suggests this memo (= 22 pp.) as an example of calibration work in practice.
    • Specific Topics to be Covered:
      • Finding T_off with frequency and/or position switching and/or chopper wheel method
      • Bandpass calibration (i.e. filter response)
      • Gain calibration
      • Pointing calibration
9/21 --- Single Dish Observing, Spectral Line Basics
  1. Single Dish Observing
    • Readings for Everyone:
    • Specific Topics to be Covered:
      • Observing Techniques: on/off, beam-switching
        • Gain stability (particularly the need to map on a timescale shorter than antenna-gain fluctuations)
      • Mapping Techniques: on-the-fly vs. grid mapping (boustrophedonic, “as the ox plows”…)
  2. Spectral line Basics
9/28 --- Fourier Transforms
  1. Fourier Transforms
    • Readings for Everyone:
    • Additional Readings for Presenters
      • FFT Wikipedia page
      • Filtering Wikipedia page
    • Specific Topics to be Covered:
      • Convolution theorem
      • Discrete vs. continuous FTs
      • Aliasing
      • FFTs
      • Basic FT examples
      • Sampling, Nyquist Theorem
      • Autocorrelation
10/5 --- Polarization
  1. Characterization of Polarization
    • Readings for Everyone:
    • Additional Readings for Presenters:
    • Specific Topics to be Covered:
      • Why do we care about polarization?
      • What is polarization, and how do we describe it?
        • Geometric description of polarization
        • Stokes parameters
  2. Measurement of Polarization
    • Readings for Everyone:
    • Specific Topics to be Covered:
      • Jones matrices
      • Mueller matrices
      • Instrumental response
        • Leakage terms
        • Beam squint & squash
      • Causes of depolarization
        • Bandwidth depolarization (Faraday rotation)
        • Beam depolarization (mention RM synthesis)
        • Optical depth depolarization
10/12 --- Interferometry I
  1. 2-element interferometer
    • Readings for Everyone:
      • Wright 10.1 = 7 pp.
      • TMS 2.1, 2.2 = 8 pp. (email pwilliams@astro.berkeley.edu for access)
    • Additional Readings for Presenters:
      • VLASS Ch.2, Sections 1-3 = 5 pp.
    • Specific Topics to be Covered:
      • Fringes
      • b-dot-s
      • Visibilities
  2. Interferometer response
    • Readings for Everyone:
      • TMS 2.3, 2.4 = 10 pp. (email pwilliams@astro.berkeley.edu for access)
      • VLASS Ch.2, Sections 7-8 = 6 pp.
      • Wright, Appendix III = 2 pp.
    • Specific Topics to be Covered:
      • Sky coordinates and (u,v) plane
      • FT relationship between visibilities and sky domain
      • Primary beam
      • Resolution
10/19 --- Interferometry II
  1. Basic properties of synthesis arrays
    • Readings for Everyone:
      • VLASS Ch.9, Sections 1,2,5 = 2 pp.
      • Wright 10.3.3 = 2 pp.
      • VLASS Ch.2, Sections 4,5 = 6 pp.
      • NOTE: Wright 10.2.1-2 should probably be here
    • Specific Topics to be Covered:
      • Sensitivity & noise
        • Radiometer equation
      • Fringe rotation
      • Delays
      • Phase center
  2. Aperture Synthesis
    • Readings for Everyone:
      • Wright 10.3.1, 10.3.2 = 5 pp.
    • Additional Readings for Presenters
      • TMS 5.6 = 15 pp.
    • Specific Topics to be Covered:
      • Filling (u,v) plane/maximizing (u,v) coverage
      • Earth-rotation synthesis
      • Synthesized beam
      • Effects of weighting on sensitivity
10/26 --- Interferometry III
  1. Correlators and Phase Switching
    • Readings for Everyone:
      • Wright 10.2.1, 10.2.2 = 2 pp.
      • Wright 10.2.4(b) should be here
      • TMS 8.7 = 16 pp. (email pwilliams@astro.berkeley.edu for access)
    • Additional Readings for Presenters
    • Specific Topics to be Covered:
      • How does the correlator work?
        • Why and how do you channelize your bandwidth?
        • The difference between XF (lag) and FX correlators
      • Why and how do you phase switch? What is a Walshing function?
  2. Calibration
    • Readings for Everyone:
      • Wright 10.2.3 = 2 pp.
      • VLASS Ch.5, Sections 1-5,7 = 21 pp.
      • VLASS Ch.10, Sections 1-4 = 8 pp.
    • Additional Readings for Presenters:
      • VLASS Ch.10, Section 5 = 4 pp.
      • CARMA calibration example 1: Click here for a high-quality CARMA observation, exhibiting T_sys vs. time, gain amplitude and phase vs. time, and bandpass amplitude vs. channel.
      • CARMA calibration example 2: Click here for a CARMA observation that would have been good had it not been for a baseline error, which caused huge phase slopes across the bandpass.
      • CARMA calibration example 3: Click here for your run-of-the-mill failed CARMA observation (failed due to weather). The data are still usable, however.
    • Specific Topics to be Covered:
      • Define the Basic Interferometric Calibrations: phase, delay, baseline (antenna positions), bandpass
        • why do you need to do each?
        • where in the visibility function does each correction appear?
        • time permitting, show a few before and after illustrations of these corrections (or just draw them on the board)
      • Selfcal
        • why do we use selfcal?
        • how does it work?
        • emphasize that selfcal preserves closure quantities (and explain what these are)
11/2 --- Imaging I
  1. Dirty map and weighting
    • Readings for Everyone:
      • TMS 10.2 = 11 pp. (email pwilliams@astro.berkeley.edu for access)
      • Wright, 10.4.1 = 2 pp.
    • Specific Topics to be Covered:
      • Give an overview of the imaging process: grid, weight, FFT
      • What is the dirty map? (show how your map is the convolution of the true sky with the FT of your uv coverage)
      • How does aliasing affect your images?
  2. Deconvolution and MFS
    • Readings for Everyone:
      • Wright 10.4.2 = 3 pp.
      • TMS 11.1-11.3 = 12 pp. (email pwilliams@astro.berkeley.edu for access)
      • TMS 11.7 = 1 p. (email pwilliams@astro.berkeley.edu for access)
    • Additional Readings for Presenters
      • VLASS Ch.8 = 29 pp.
    • Specific Topics to be Covered:
      • Selfcal
        • why do we use selfcal?
        • how does it work?
        • emphasize that selfcal preserves closure quantities (and explain what these are)
      • Deconvolution methods: CLEAN, Maximum Entropy
        • fancier methods: multi-resolution clean
      • Describe multi-frequency synthesis (MFS): taking advantage of spectral uv coverage
11/9 --- Imaging II
  1. Imaging errors and data editing
    • Readings for Everyone:
      • VLASS Ch.5, section 6 = 3 pp.
      • VLASS Ch.17, sections 1.1, 1.2 = 6 pp.
      • VLASS Ch.15 = 23 pages
    • Additional Readings for Presenters
      • Lecture on this topic at VLA Summer School
    • Specific Topics to be Covered:
      • Present examples of imaging errors and how to recognize them:
        • their characteristics
        • their causes
        • errors listed in ch. 15 and time, bandwidth smearing
      • Justify why data editing is acceptable
        • how many datà get edited‽ : a lot
11/16 --- Imaging III: Wide-field Imaging
  1. Non-coplanar imaging
    • Readings for Everyone:
    • Additional Readings for Presenters
      • VLASS Ch. 19 sections 1.1-1.3 = 5 pp.
    • Specific Topics to be Covered:
      • What is the w term and when do you need to worry about it?
      • Describe some methods for handling wide fields:
        • faceted (polyhedron) imaging
        • w-projection
  2. Mosaicking
    • Readings for Everyone:
    • Specific Topics to be Covered:
      • Describe why we use mosaicking and some complications involved
11/18 --- Imaging IV: Spectral Line and Polarization Considerations
  1. Spectral Line
    • Readings for Everyone:
      • VLASS Ch.12, Section 11 = 10 pp.
      • VLASS Ch.12, Section 6 = 9 pp.
    • Specific Topics to be Covered:
      • Describe moment maps
      • What is beam smearing?
      • Describe different methods of continuum subtraction and advantages / disadvantages of each
  2. Polarization
    • Readings for Everyone:
      • TMS 4.8, pp. 112-117 = 5 pp. (email pwilliams@astro.berkeley.edu for access)
      • VLASS Ch.6, Section 7 = 3 pp.
    • Specific Topics to be Covered:
      • How do you calibrate your instrumental polarization?
      • Discuss considerations for imaging polarization products:
        • Q,U,V can be negative
11/30 --- Berkeley radio astronomy; wrap-up
  1. Radio astronomy in the Berkeley community
    • CARMA, ATA, PAPER, and others
  2. Clarification of topics; wrap-up

Class List

Name Department Email
Casey Law Astronomy claw AT astro DOT berkeley DOT edu
Therese Jones Astronomy tjones AT astro DOT berkeley DOT edu
Karol Sánchez Astronomy 0lorak AT gmail DOT com
Meredith Hughes Astronomy a DOT meredith DOT hughes AT gmail DOT com
Terry Filiba EECS tfiliba AT eecs DOT berkeley DOT edu
James McBride Astronomy jmcbride AT astro DOT berkeley DOT edu
Aritoki Suzuki Physics asuzuki AT berkeley DOT edu
Aaron Lee Astronomy alee AT astro DOT berkeley DOT edu
Andrew Siemion Astronomy siemion AT berkeley DOT edu
Christopher Klein Astronomy cklein AT berkeley DOT edu
Steve Croft Astronomy scroft AT berkeley DOT edu
Frank Serduke Astronomy frank AT serduke DOT com
Jim Scala N/A jscala2 AT comcast DOT net
Delia Tosi Physics deliatosi AT gmail DOT com
Katie Silverio Astronomy silverio AT astro DOT berkeley DOT edu
Keaton Burns Math kburns AT berkeley DOT edu
Adam Miller Astronomy amiller AT astro DOT berkeley DOT edu
Nicholas McConnell Astronomy nmcc AT berkeley DOT edu
Alexie Leauthaud LBNL asleauthaud AT lbl DOT gov
Erik Petigura Astronomy epetigura AT berkeley DOT edu
Lorenzo Faccioli LBNL lfaccioli AT lbl DOT gov
Katey Alatalo Astronomy kalatalo AT astro DOT berkeley DOT edu
Gregory Désvignes Astronomy gdesvignes AT astro DOT berkeley DOT edu
Karto Keating Astronomy gkeating AT astro DOT berkeley DOT edu
Imke de Pater Astronomy imke AT berkeley DOT edu
Dan Werthimer BWRC/SSL danw AT ssl DOT berkeley DOT edu
Dick Plambeck Astronomy plambeck AT astro DOT berkeley DOT edu
Mel Wright Astronomy wright AT astro DOT berkeley DOT edu
Dave MacMahon Astronomy davidm AT astro DOT berkeley DOT edu
Carl Heiles (faculty sponsor) Astronomy heiles AT astro DOT berkeley DOT edu
Geoff Bower (faculty sponsor) Astronomy gbower AT astro DOT berkeley DOT edu
Chat Hull (organizer) Astronomy chat AT astro DOT berkeley DOT edu
Jonathan Pober (organizer) Astronomy jpober AT berkeley DOT edu
Statia Luszcz-Cook (organizer) Astronomy statia AT berkeley DOT edu
Amber Bauermeister (organizer) Astronomy amberb AT berkeley DOT edu
Peter Williams (organizer) Astronomy pwilliams AT astro DOT berkeley DOT edu
Organizers Astronomy radio101 AT lists DOT berkeley DOT edu
Class List N/A radio101_f10 AT lists DOT berkeley DOT edu