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Supporting material for Lecture 1: Role of atmosphere in astronomical observations

Supporting material for Lecture 1: Role of atmosphere in astronomical observations Definition of angular resolution Optical, radio, X-ray telescopes. Atmospheric absorption. Telescopio Nazionale Galileo (3.5m). Hubble Space Telescope (2.4m). 2.5m Mount Wilson telescope.

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Supporting material for Lecture 1: Role of atmosphere in astronomical observations

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  1. Supporting material for Lecture 1: Role of atmosphere in astronomical observations Definition of angular resolution Optical, radio, X-ray telescopes

  2. Atmospheric absorption

  3. Telescopio Nazionale Galileo (3.5m) Hubble Space Telescope (2.4m) 2.5m Mount Wilson telescope

  4. Resolution or minimum resolvable distance is the minimum distance between distinguishable objects in an image Sources with angular size larger than the resolution are called Extended, otherwise their are point-like, i.e., their angular Extent does not exceed the point spread function The resolution of ground-based optical images is limited by the Atmospheric seeing (about 1-2 arcseconds on average). How can one overcome the atmospheric limitation in optical? By using adaptive optics By using interferometry By putting a telescope in space (HST)

  5. Adaptive optics use wavefront sensors to adapt a deformable mirror to variations of the local seeing Adaptive optics at Gemini telescope

  6. Luminous infrared galaxy IRAS 18293-3413 (79 Mpc) Comparison of NTT/SOFI and VLT/NACO images Angular size of each image: 16.5” x 11.5”

  7. INTERFEROMETRY With an ARRAY of telescopes I can combine the wave trains (aperture synthesis) and improve the resolution Very Large Telescope: Four 8.2m telescopes Resolution = /B B = Baseline

  8. VLTI/AMBER discovers a companion to HD 87643 By image synthesis

  9. VLT NACO Comparison of ground-based optical and HST Images of the Homunculus Nebula around Eta Carinae. The Larger axis of the nebula is about 30 arcseconds HST-WFPC2

  10. Radiotelescopes Natural concavities favour Screening from human-related Radio-interference Resolution: ~10 arcmin Parabola in Medicina, Bologna (32m) Arecibo (100m)

  11. Radiointerferometry: Aperture synthesis Croce del Nord (Medicina) Angular resolution: ~1 arcsec Very Large Array (New Mexico)

  12. Very Long Baseline Interferometry (ang. Res.: milliarcsecond) European VLBI Network (EVN) Very Long Baseline Array (VLBA)

  13. The VLBI Space Observatory Program (VSOP) HALCA: Japanese 8m Antenna orbiting the Earth Ang. Res: milli-to-microarcsec 30000 km Halca Relativistic jet Of the active galaxy Mkn501 (z = 0.033)

  14. X-ray telescopes: grazing incidence

  15. X-ray observations of Eta Carinae Chandra XMM-Newton ASCA

  16. X-ray: 0.1 - 100 keV The history of X-ray astronomy started in the 1960s: R. Giacconi 2003: Nobel Lecture: The dawn of x-ray astronomy Reviews of Modern Physics 75, 995 In 40 years the X-ray flux sensitivity has improved by 10 orders of magnitudes, comparable to the improvement in optical instruments sensitivity in the last 400 years! First high-energy baloon experiments: about e-08 erg/s/cm2 Chandra (launched 1999): e-18 erg/s/cm2

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