Telescopes continued… Why is bigger better? Two reasons…
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Transcript of Telescopes continued… Why is bigger better? Two reasons…
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Telescopes continued…
Why is bigger better?
Two reasons…
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(1) Light-gathering power
• Depends on the area of the objective mirror (or lens)
• Compare 16-inch to our 10-inch scopes:
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(2) Resolution of telescopes• Angular resolution depends on telescope
diameter (D) and signal wavelength (λ):
Rayleigh criterion: Θmin ~ λ / D
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Some numbers …For optical wavelengths, Θ in arc-seconds, and D in inches it
works out to Θmin ~ 4.5 / D
Example: for your 10-inch telescopes,
Θmin ~ 4.5/ 10 = 0.45 arc-sec
(note garage sale signs…)
Above for diffraction-limited situations like space telescopes. Our atmospheric limits actual results.
Overcome atmospheric limits with active optics.
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Mayal 4-m
McMath solar telescope
Wynn
•Near Tucson
•Tax supported with other consortia, too
•Nice public program
•Tucson: good lighting
Kitt Peak National Observatory
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Mayal 4-meter
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McMath solar telescope
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Originally separate mirrors as shown here
Whole building rotates
Operated by the Smithsonian Institution, founded with funds from British scientist James Smithson, who bequeathed his fortune to America for the creation of an institute for the “increase and diffusion of knowledge.” Now looks like ….
The MMT (Mt. Hopkins, SE AZ)
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New MMT 6.5-meter
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Also on Hopkins: LBT
• Large Binocular Telescope
• Twin 8.4-m mirrors
• Optical interferometry
• Will image extrasolar planets
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And: VATT & SMT
• Vatican Advanced Technology Telescope
• Univ. Arizona Sub-Millimeter Telescope
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Mauna Kea , Hawaii – Keck, Gemini, Suabaru, NASA, and others
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Gemini (North) 8-m Telescope …
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8-meter spin-cast mirror
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Twin Keck 10-m Telescopes
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Keck segmented primary mirror
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European Southern Observatory (Chile)
Why the shift to southern hemisphere?
VLT four 8-m’s
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European Southern Observatory 3.6-m
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Cerro Tololo nearby with the Blanco 4-m, a twin to Kitt Peak 4-m
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DuPont 2.5-m also there
Supporting this closed Mt. Wilson 100-inch
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Gemini South and SOAR on nearby Cerro Pachỏn
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Gemini South
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SOAR = Southern Observatory for Astrophysical Research
How’s it coming?...
UNC-CH (17%) and others
PROMPT …