The Chandra gamma (and x-ray) observatory: Named after 1983 Nobel laureate Subrahmanyan Chandrasekhar. Example: Very Large Array In New Mexico Slide 25 Very Long Baseline Array: Worlds largest aperture Slide 26 Satellites: necessary for most infrared, x-ray, gamma ray, micro-wave, UV. Slide 24 Interferometry: using two telescopes or more and time delays on computer to simulate on large telescope. Resolution-the angle of separation at which two objects merge and look like one. Magnification-m = F/f (F focal length of objective, f focal length of eyepiece) Slide 23 3. Light gathering power-proportional to the area of objective. Slide 17 The Keck Twin Telescopes in Hawaii compensate for turbulence by mechanically bending component mirrors. Atmospheric turbulence-why stars twinkle. Slide 16 Seeing-the following conditions interfere with clear viewing: 1. Distance between lenses is a little more than the sum of the two focal lengths. Slide 15 Refracting telescope (refractor): A large objective lens (usually converging) focuses an image and a small eyepiece lens magnifies it. Slide 14 A large curved objective mirror focuses an image, a small eyepiece lens magnifies it. Slide 13 Telescopes Reflecting or Newtonian telescope (reflector): Equatorial Mount. Uhuru-xray satellite discovered first black hole. Satellites: necessary for most infrared, x-ray, gamma ray, micro-wave, UV. Interferometry: using two radio telescopes or more and time delays to simulate on large telescope. Magnification-m = F/f (F focal length of objective, f focal length of eyepiece) 3. Seeing-the following conditions interfere with clear viewing: 1. Refracting telescope (refractor): A large objective lens (usually converging) focuses an image and a small eyepiece lens magnifies it. Slide 12 NOTES: Telescopes Reflecting or Newtonian telescope (reflector): A large curved objective mirror focuses an image, a small eyepiece lens magnifies it. Slide 11 The images are real or virtual: Real images are formed by light rays virtual images are notthey are optical illusions. Slide 10 Lenses make images: We can use ray diagrams with three principal rays to determine where they are. Different colors (wavelengths) have different speeds of light, and diffract over different angles. Slide 9 Problem: lenses suffer from chromatic aberration. Converging or convex lens Diverging or concave lens Note: rays from a distant object come in nearly parallel. Slide 8 This principle is used in lenses. Slide 7 The speed of light is smaller in glass or water than in air. This is because the speed of the wave is smaller in shallow water. They change their path when coming in at an angle. Slide 6 This is similar to waves on the ocean. Slide 5 Principle of refraction: light bends when it passes at an angle between two media with different speeds of light like air and glass. (Note: each ray Is reflected at an angle = to its angle of incidence.) A parabolic mirror focuses rays to a point Slide 4 but a spherical mirror does NOT! Most cheap telescope mirrors are spherical, but the distortion is minimal. Slide 3 The Focal length of a mirror is the distance from the mirror parallel rays hitting it focus to a point. Slide 2 Principle of reflection: the angle of incidence equals the angle of reflection -for all mirrors, flat or curved. A concave or diverging lens is curved inward on both sides. A convex or converging lens is curved outward on both sides. Rays from a distant object may be considered to be parallel rays. Lenses The Focal length of a lens is the distance parallel rays entering the lens focus to a point. Principle of refraction: light bends when it passes at an angle between two media with different speeds of light like air and glass-lenses utilize this principle to focalize images. Spherical mirrors (cheaper to make) work only close to the axis. A parabolic mirror creates an image with no distortion. NOTES: Reflection and Refraction Principle of reflection: the angle of incidence equals the angle of reflection-for all mirrors.
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