ASTRcheatsheet2 - NOTES Telescopes Refractor (lenses)...

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NOTES Telescopes Refractor (lenses) Reflective (mirrors) – object flips - parabola = optimal shape - advantages: no chromatic aberration don’t block any λ s heaviest piece at bottom of scope only have to clean one surface Types of reflectors: Prime focus (big scopes) Newtonian Cassegrain Nasmyth/Coudé Hybrids (spherical mirror + lens) - Schmidt scopes Detectors: Photographic plates (1920’s-70’s) 2% CCDs 50-95% efficiency; $$$ Spectro-graph/scopy Disperser – prism, grating Reflection, transmission Relief , VPH Detector – plates, CCDs Scope size: light gathering power area - 5m gathers 25x more light than 1m ( π r^2) - biggest in Chile + Hawaii Resolving Power: smaller scopes blur more light Atmospheric blurring/seeing - air pockets in atms diff temps/densities - blue λ s scatter easily -> blue sky ~1” w/o adaptive optics Active Optics – good design considerations - ex. Mirror shape + temp, dome airflow Adaptive Optics – use guide star - rapidly moving small mirror + rapid imaging/computing UNC scopes: Morehead, SOAR (4m), SALT (11/9m), PROMPT, Skynet Radio Astronomy (BIG); NRAO - UV thru gamma blocked by O3 - IR blocked by H2O, CO2 - Green Bank, WVA (140’, 300’, Tatel) Interferometry: multiple radio scopes, compare wave interference (ex. VLA) - great angular res. (eq. baseline = diam.) Space-based scopes: Spitzer (IR), Hubble (near IR – UV) -> Webb, Chandra (X-Rays, imaging), Newton
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This note was uploaded on 02/13/2012 for the course ASTR 101 taught by Professor Christiansen during the Fall '08 term at UNC.

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ASTRcheatsheet2 - NOTES Telescopes Refractor (lenses)...

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