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ASTR 567: Observational Techniques in Astronomy

ASTR 567: Observational Techniques in Astronomy. Grading Scheme. Start of lecture quizzes………………….. 10% Homeworks ……………………………………..25% Highest of two midterm grades……….25% Telescope Proposal………………………….15% Final Exam……………………………………….25%. Gathering Data in Astronomy.

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ASTR 567: Observational Techniques in Astronomy

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  1. ASTR 567: Observational Techniques in Astronomy

  2. Grading Scheme • Start of lecture quizzes………………….. 10% • Homeworks……………………………………..25% • Highest of two midterm grades……….25% • Telescope Proposal………………………….15% • Final Exam……………………………………….25%

  3. Gathering Data in Astronomy • What are some ways we gather information about the cosmos?

  4. Gathering Data in Astronomy In Situ Particles with Mass Cosmic rays Neutrinos Meteorites Solar wind Solar system probes Apollo lunar landings Massless Particles Gravitons Photons

  5. AST563: Astroparticle Physics • Offered in spring semester • Covers neutrinos, cosmic rays, dark matter, gravitational waves

  6. AST562: High Energy Astrophysics • Offered this semester: Prof. Lyutikov • Physics of exotic objects: neutron stars, white dwarfs, supernovae, black holes, magnetars

  7. Electromagnetic Radiation • Light exhibits wave-particle duality: • Massless light quanta: photons, carry a specific energy: E = hν = hc/λ h = Planck’s constant = 6.6261 × 10-34 m2 kg / s c = speed of light = 299 792 458 m / s • Light can also reflect, refract, diffract, polarize, andinterferewith itself.

  8. Production of E/M Waves • Electromagnetic waves are created by accelerating a charged particle E/M radiation emitted from a vertically oscillating magnetic dipole

  9. Production of E/M Waves • In the quantum view, a photon is created when an electron jumps to a lower energy state or a free electron binds to an atom.

  10. Production of E/M Waves • Other types of quantum transitions that produce photons: Electron spin flip in hydrogen Vibration & Rotation Modes

  11. Production of E/M Waves • Nuclear processes can also produce photons: • electron+positron annihilation • nuclear fission and fusion • radioactive decay

  12. E/M Wave Structure • E/M wave requires no medium (‘ether’) • E and B fields oscillate  to each other, sustaining the wave • In a vacuum, wave travels in a straight line (geodesic) at constant speed c = λν

  13. E/M Bands • Divisions between bands are approximate: none are officially standardized. • Sub-divisions are common e.g., near-IR, far-UV, soft X-ray • near, soft : longer λ • far, hard : shorter λ

  14. Astronomical Techniques All photon-based astronomical measurements can be classified as one or more of: • Photometry • Spectroscopy • Polarimetry • Astrometry • Imaging • All of these exploit the wave and/or particle properties of E/M radiation

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