Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Hubble Space Telescope wikipedia , lookup
Spitzer Space Telescope wikipedia , lookup
Arecibo Observatory wikipedia , lookup
International Ultraviolet Explorer wikipedia , lookup
James Webb Space Telescope wikipedia , lookup
CfA 1.2 m Millimeter-Wave Telescope wikipedia , lookup
Leibniz Institute for Astrophysics Potsdam wikipedia , lookup
Allen Telescope Array wikipedia , lookup
Optical telescope wikipedia , lookup
Optical and infrared astronomical telescopes and instruments (L16) Ian Parry Astronomy is an observational science. Our understanding of the universe beyond the Earth comes mostly from interpreting the electromagnetic radiation we see coming from the sky. This course is about the equipment and techniques that we use to collect and measure the optical and near infra-red component of this radiation (approximately 0.3 to 5 microns in wavelength). The material presented will give the student a thorough understanding of how telescopes and their instruments actually work. An important aim of the course is to quantify how well they work leading to an understanding of what defines the state-of-the-art and what its limitations are. Specific topics will be selected from the following list; 1. Introduction: Effects of the Earths atmosphere, transparency, seeing, refraction, dispersion, basic definition of magnitudes. 2. Positional astronomy and coordinate systems: Sidereal time, right ascension, declination, hour angle, aberration of starlight, spherical trigonometry, great circles, small circles, spherical triangles, cosine and sine rules, tangent plane. 3. Optics: geometrical optics, lens-makers equation, principle planes, focal length, f-number, aberrations, paraxial approximation, ray-tracing, image planes, pupil planes, conjugate planes, simple lens design, achromatic lenses, the Petzval lens, methods of designing complex optical systems, tendue, physical optics, quantum optics, Fourier treatment of wave propagation. 4. Telescopes. Refractors, reflectors, parabolic reflectors, Ritchey-Chretien telescopes, 3mirror anastigmats, the Schmidt telescope, ground-based telescopes, telescope mounts, space-based telescopes. 5. Detectors: photo-electrons, useful semiconductor types, readout architectures, image intensifiers, linearity, dynamic range, quantum efficiency, pixel-to-pixel variations, readout noise, dark-current, sensitivity to cosmic rays, defects, charge transfer, artefacts. 6. Adaptive Optics: wavefront sensors, deformable mirrors, control algorithms, Kolmogorov turbulence, Zernike polynomials. 7. Imagers: eyepieces, the eye, magnification, collimators, cameras, detector matching, image scale, field of view, filters, magnitude systems. Fabry Perot interferometers, polarimetry. 8. Coronagraphs: Fourier modelling, speckles, occulters, lyot-stop, apodization, 9. Spectrographs: Dispersive spectrometers (long-slit, multi-slit, multi-fibre, echelle, integral field), disperser types, grating equation, spectro-polarimetry, Fourier-transform spectrometers. 10. Interferometers:, Stellar interferometry: Fizeau-Stephan interferometer, Michelson stellar interferometer, closure-phase, non-redundant masks. 11. Signal-to-noise ratio: exposure time, Poisson noise, systematic errors, beam-switching, cryogenics. 12. Future projects: E-ELT, LSST, JWST, HDST. 1 Pre-requisites This course is self-contained. Literature 1. Roy, A.E., & Clarke, D., Astronomy Principles and Practice, 4th ed., Institute of Physics, 2003. 2. Kitchin, C.R.: Astrophysical Techniques, 4th ed., Institute of Physics, 2003. 3. Smart, W.M., Spherical Astronomy, 6th ed., Cambridge University Press, 1977. 4. Saha S. K., Diffraction-limited imaging with large and moderate telescopes, World Scientific, New Jersey, 2007. 5. Born & Wolf, Principles of Optics, 7th ed., Cambridge University Press, 2002 6. Optics : E.Hecht 7. Speckle Phenomenon in Optics : J.W.Goodman 8. Astronomical Optics : D.J.Shroeder 9. Astronomical Techniques : W.A.Hiltner 10. Optical Detectors for Astronomy : J.W.Beletic & P.DAmico Additional support Three examples sheets will be provided and three associated examples classes will be given. There will be a one-hour revision class in the Easter Term. 2