The aim of this course, which comprises nominally of 22 hour lectures, is to give a general introduction to optical and infrared observational astronomy, emphasizing the instrumentation and techniques used. This includes discussion of basic telescope optics and design, active and adaptive optics, techniques for light detection and the principles and practices employed in photometry, spectroscopy and polarimetry. Particular emphasis is given to real instrumentation used at the Sutherland observatory site of the SAAO, including the Southern African Large Telescope (SALT) and its instruments.
Illustrated examples are given of the different types of science achieved by various astronomical instruments and techniques. Practicalities of observing and reducing astronomical data are also introduced in the course. The concept of the Virtual Observatory (VO) is presented, which includes a tutorial session in the NASSP computer laboratory using various VO tools. Similarly, how users apply for observing time with SALT and define their observational requirements using the various observation simulation software tools, is presented together as well as conducting a hands-on tutorial session.
A project, comprising 40% of the assessment for the course, will be completed over ~ 6 weeks. The project will include a written report and oral presentation.
A tutorial based on Virtual Observatory exercises will comprise 10% of the assessment.
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Observing Basics (2 lectures, DB)
Astronomical coordinate systems; spherical trigonometry; precession & nutation; parallax; proper motions; stellar aberration; atmospheric diffraction and dispersion; time systems.
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Telescopes (2 lectures, DOD; 3 lectures, DB)
Basic optics; aberration theory; telescope parameters and configurations; telescope lenses, mirrors, tubes, mounts, domes and enclosures; mirror coatings; active and adaptive optics (A-O); optical nature of the Earth’s atmosphere, Fried parameter and structure parameters; Optical and Modulation Transfer Functions; Strehl ratio; science with AO; modern large telescopes; the Southern African Large Telescope (SALT).
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Detectors (4 lectures, DB + SAAO workshop visit)
The human eye; the magnitude scale; photographic techniques; photoelectric effect; photomultiplier tubes; image tubes; microchannel plates; semi-conductor basics; CCD principles; CCD design and operation; noise sources and signal to noise equation; cosmetic defects; practicalities of CCD data reductions; demonstration of CCD operation
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Photometry (2 lectures, DB)
Absolute and bolometric magnitudes; colour index; blackbodies; filters and photometric systems; spectral energy distributions; two-colour diagrams; dust extinction and reddening; line blanketing; colour-magnitude (C-M) diagrams; atmospheric extinction, absorption and emission; reducing photometric data; differential photometry; Fourier theory and period analysis; case studies: Whole Earth Telescope (WET) and SALTICAM observations; drift scanning.
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Spectroscopy Principles (2 lectures, DB)
Early history; dispersion and prisms; objective prism spectroscopy; diffraction gratings, the grating equation and grating parameters; échelle gratings; grisms; volume phase holographic gratings (VPHGs); spectrometer design, collimators and cameras; spectrograph examples including the SALT RSS; slit effects; CCD gain and digitization; signal to noise calculations; sky background.
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Spectrographs and Applications (2 lectures, DB)
Échelle spectrographs; échelle spectrograph examples: GIRAFFE and the SALT HRS; novel VPH gratings; imaging spectroscopy; multi-fibre spectroscopy; Fabry-Perot (F-P) spectroscopy; RSS F-P mode example; Integral Field Unit (IFU) spectroscopy; lenslet arrays; astrophysical insights from spectroscopy; stellar spectral types & luminosity classes; the M-K classification system; temperature and luminosity effects on spectra; other spectral classes; H-R and C-M diagrams; examples of spectra; brown dwarfs; non-stellar spectra; radial velocity measurements.
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Virtual Observatory (1 lecture, SB)
Definition of the VO; VO tools; VO examples.
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Near Infrared Techniques (1 lecture, PAW)
Challenges posed by observing at infrared wavelengths and how they are dealt with; infrared detectors and photometers and their use on the various telescopes at Sutherland. A detailed discussion of why we bother with observing at infrared wavelengths, given how difficult it is.
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Polarimetry (2 lectures, SBP)
Polarization; Stokes parameters; observing methods and data analysis; HIPPO: the new SAAO polarimeter; spectropolarimetry
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Variable Stars as Observational Examples (2 lectures, PM)
Types of variable stars; naming conventions; spectroscopic and eclipsing binaries; reflection effect; limb darkening; gravity brightening; the binary pulsar; eruptive variables; radial and non-radial pulsations; driving mechanisms; the Baade-Wesselink method; types of pulsating stars: Cepheids, RR Lyrae, δ Suti, γ Doradus, White Dwarf pulsators.