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Syllabus for

Academic year
RRY131 - Radioastronomical techniques and interferometry
 
Syllabus adopted 2013-02-20 by Head of Programme (or corresponding)
Owner: MPPAS
7,5 Credits
Grading: TH - Five, Four, Three, Not passed
Education cycle: Second-cycle
Major subject: Electrical Engineering, Engineering Physics
Department: 75 - EARTH AND SPACE SCIENCES


Teaching language: English
Open for exchange students
Block schedule: C

Course module   Credit distribution   Examination dates
Sp1 Sp2 Sp3 Sp4 Summer course No Sp
0113 Project 3,0 c Grading: UG   3,0 c    
0213 Examination 4,5 c Grading: TH   4,5 c   19 Dec 2013 pm M,  24 Apr 2014 am V,  26 Aug 2014 am V

In programs

MPPAS PHYSICS AND ASTRONOMY, MSC PROGR, Year 2 (elective)
MPWPS WIRELESS, PHOTONICS AND SPACE ENGINEERING, MSC PROGR, Year 2 (elective)

Examiner:

Forskare  Carina Persson
Professor  John Conway


Replaces

RRY130   Radioastronomical techniques and interferometry


Eligibility:

For single subject courses within Chalmers programmes the same eligibility requirements apply, as to the programme(s) that the course is part of.

Course specific prerequisites

Basic knowledge in electromagnetism.

Aim

The aim of the course is that students to understand radio astronomy techniques and the astrophysical goals motivating radio astronomy measurements. The course shall enable the students to plan an astronomical experiment using either single dish or interferometry, and to determine the required integration time, choice of instrument etc. The course will explain how to go from raw radio astronomy data to final images/spectra. The level of understanding should be such that the students in their profession as engineers or scientists should be able to apply radioastronomical techniques.

Learning outcomes (after completion of the course the student should be able to)

* describe which physical quantities can be measured by radio telescopes

* describe in words different continuum and spectral line radiation mechanisms

* describe how radiation intensity depends on physical parameters for different radiation mechanisms

* from given physical parameters (density, temperature, velocity width etc) in an object at a given distance calculate observed intensity, frequency width, surface brightness (brightness temperature) etc.

* be able to take an Spectral Energy Distribution of a typical object (star, active galaxy etc) and determine which frequency ranges it can be observed by different telescopes

* calculate needed angular resolution for required science needs and resolution available from different telescopes (is an interferometer needed?)

* determine which declinations can be observed from which latitudes on Earth and hence choice of telescope

* describe the basic operation of a radio telescope and its instrumentation

* select an appropriate observational technique (e.g. frequency - beam - position switching, polarization measurements, fast scanning) for a given astronomical object

* estimate needed signal to noise and calculate required integration time

* plan, carry out and evaluate a single dish astronomical observation

* perform basic analysis of single dish data (e.g. single pointing spectral line analysis and identification and mapping)

* determine when interferometric angular resolution is needed to carry out an observation and how resolution depends on baseline length

* determine the needed short spacing coverage of an interferometer to image extended structure

* determine the required uv coverage to image sources of different complexity (source positions and flux density from a single baseline, source sizes from several baselines and complex images needing very full uv coverage)

* determine which of the available interferometers (VLA, MERLIN, LOFAR, ALMA etc has the right frequency, resolution, uv coverage for a given type of observation)

* understand concepts of point source and surface brightness sensitivity. Calculate required integration time for an interferometric observation

* visualise a simple two element ('non-tracking') interferometer observing at the zenith and the output responses due to point sources at different positions and strength

* describe to other students what is meant by 'spatial frequency' in connection with 2D Fourier transforms

* show via diagrams how a tracking interferometer measures a given spatial frequency depending on the projected baseline length as seen from the source

* write computer programs showing that a single interferometer baseline samples an ellipse in the u,v plane

* explain how the dirty image is made and show mathematically that it is the convolution of true source with dirty beam

* understand the need for deconvolution and explain the CLEAN algorithm sufficiently well that it could be coded by someone else

* explain how closure phases are used to recover experiment phase in redundant arrays and how 'self-calibration' can converge

* be able reduce simple interferometry data, going from amplitude calibrated continuum visibility data to a final image using CLEAN and self-calibration

* describe mathematically the operation of a spectral line interferometer

Content

The course contains the following parts:

* Single dish radioastronomy.
* Fundamental concepts.
* Basic antenna theory.
* Receiver and signal processing.
* Observational methods.
* Radioastronomical objects.
* Spectral line analysis.
* Planning a single dish observation.
* Observing with the Onsala 20m telescope.
* Single dish data reduction.

* The 2-element non-tracking interferometer.
* The tracking interferometer.
* The 2D Fourier transform.
* 'uv' coverage for example interferometers.
* The dirty map and dirty beam.
* Noise in interferometry images.
* Properties of the main interferometric radio telescopes one can propose to.
* Planning an interferometer observation.
* Deconvolution methods.
* Phase errors and their recovery using closure phase and self-calbration.
* Interferometric data reduction.
* Spectral line interferometry.
* Applications of the interferometry technique in other disciplines (i.e. geodetic VLBI).
* Design of future ratio telescope (e.g SKA) and use of aperture arrays.

Organisation

Lectures, problem classes, practical observations, and computer excercises.

Literature

Lecture notes and Tools of Radioastronomy by K. Rohlfs and T.L. Wilson, Springer Verlag, last edition (available as a web book for those with Chalmers library card).

Examination

Written exam plus hand in assignments.


Page manager Published: Mon 28 Nov 2016.