1. Chapter 3 Telescopes

2. Gemini North Telescope, Mauna Kea, Hawaii

3. Optical telescopes Light buckets Reflectors and refractors Advantages of reflectors Reflecting telescope designs

4. Reflection and Refraction Reflection - the bouncing of light (or EM radiation) off of a shiny surface Refraction - the bending of light as it travels from one transparent substance to another

5. Figure 3.1 - Reflecting Mirror

6. Figure 3.1 Analogy - Light Bucket

7. Figure 3.2 - Refracting Lens

8. Figure 3.3 - Image Formation

9. Figure 3.4 - Reflectors and Refractors

10. Reflecting Telescope Advantages No chromatic aberration No UV or IR absorption Supported at back (lenses supported at edges) Only has one optical surface

11. Figure 3.5 - Reflecting Telescopes

12. Figure 3.6 Keck Telescope

13. Discovery 3-1 The Hubble Space Telescope

15. Detectors Photographic film Charge-coupled devices or CCDs CCDs more efficient (75% vs. 5%) CCDs collect data in digital format

16. Figure 3.7acd CCD Chip

17. Figure 3.7b CCD Chip

18. Figure 3.8 - Image Processing a) ground based, b) HST flawed, c) image processed, d) HST fixed

19. Light-gathering power Depends on collecting area of mirror Area  diameter 2

20. Figure 3.9 Sensitivity Same Exposure time, but (b) taken with twice the size telescope as (a)

21. Figure 3.10 - Mauna Kea Observatory a) Aerial view, b) Subaru telescope one piece mirror

22. Figure 3.11 - VLT Observatory - Paranal Observatory, Atacama, Chile

23. Resolving power Ability to see fine detail Larger diameter mirror resolves finer detail More detail at shorter wavelengths Limited by diffraction

24. Figure 3.12 - Resolution (a) 10’ (b) 1’ (c) 5” (d) 1”

25. Figure 3.13 - Diffraction

26. Seeing Atmospheric blurring Seeing disk - circle over which star’s light is spread Stars twinkle Planets don’t

27. Figure 3.14 - Atmospheric Turbulence

28. New telescope designs Active optics - control environment and mechanics of telescope Adaptive optics - control mirror shape in real time to remove effects of atmosphere

29. Figure 3.15 - Active Optics (a) without (b) with active optics

30. Figure 3.16 - Adaptive Optics

31. Figure 3.17 - Radio Telescope

32. DirecTV dish at far southern latitudes Large size Low angle El Chalten, Argentina

33. Figure 3.18 - Arecibo Observatory

34. Figure 3.19 - Radio Galaxy

35. Interferometer Telescopes in an array Combine signals Increases resolving power Resolving power determined by array size Photon-gathering power determined by total area of reflectors

36. Figure 3.20 - VLA Interferometer

37. Figure 3.21 - Interferometry

38. Figure 3.22 - Radio-optical Comparison

39. Figure 3.23 - Optical Interferometry

40. Figure 3.24 Infrared Telescope

41. Figure 3.25 - Infrared Images

42. Figure 3.26 Ultraviolet Images

43. Figure 3.27 - X-ray Telescope Reflection at grazing angles

44. Figure 3.28 Chandra (X-ray) Observatory

45. Figure 3.29 X-Ray Image of Supernova Remnant

46. Figure 3.30 - Gamma-ray Image Gamma-ray blazar in 3C279

47. Table 3-1 Astronomy at Many Wavelengths Table 3.1

48. Figure 3.31 Milky Way Galaxy at Multiple Wavelengths