Galileo, Brahe, and Kepler

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Future Telescopes
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Areas of Telescope Advancement

• Gather more light
• Larger mirrors (or many smaller ones)
• Sharper images
• Larger mirrors or arrays of mirrors
• Correct for blurring of atmosphere (adaptive
  optics)
• Space satellites (e.g., Hubble)
• Images of larger areas
• Specially-designed telescope optics
• Cameras with large detector arrays
• More sophisticated instruments
• High spectral resolution
• Multi-object spectroscopy
• Adaptive optics

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Day
Night
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The largest single mirrors are currently 8 m in
diameter. Rather than use larger mirrors, future
telescopes will contain arrays of mirrors.
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Smaller mirrors are easier and cheaper to build,
so larger telescopes often use segmented mirrors
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The largest optical/IR telescopes currently have
mirror diameters of 10 m. The next generation of
telescopes should reach 30-100 m
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Improvement in resolution from 1 to 100 m
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Large Synoptic Survey Telescope (LSST)
LSST is a 8.4 telescope that will use a
wide-field camera to image 2/3 of the sky 1000
times at optical wavelengths from 2016-2026. The
primary goals are the discovery of all large
near-Earth asteroids (gt100 m) and measurements of
dark energy.
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LSST camera
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Searching for Asteroids with LSST
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Imaging through a perfect telescope

• With no turbulence, FWHM is diffraction limit of
  telescope, ? l / D
• Example
• l / D 0.02 for l 1 mm, D 10 m
• With turbulence, image size gets much larger
  (typically 0.5 - 2)

FWHM l/D
in units of l/D
Point Spread Function (PSF) intensity profile
from point source
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How does adaptive optics work?
Measure details of blurring from guide star
near the object you want to observe
Calculate (on a computer) the shape to apply to
deformable mirror to correct blurring
Light from both guide star and astronomical
object is reflected from deformable mirror
distortions are removed
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Comparison of normal seeing and AO
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Neptune with AO on Keck (10 m)
normal seeing
Keck AO
2.3 arc sec
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Neptune with Hubble and Keck AO
HST
Keck AO
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Limitations of AO

• most AO systems are restricted to IR very
  difficult in optical
• AO correction applies to only a very small patch
  of sky
• need bright star near target for wavefront
  correction, although lasers can be used to create
  artificial stars

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Stratospheric Observatory for IR Astronomy (SOFIA)
SOFIA is a 2.5 m IR telescope that will soon be
deployed on a modified 747.
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SOFIA will observe at wavelengths that are
blocked by the atmosphere for telescopes on the
ground
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Example of a SOFIA flight path
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Example of a SOFIA flight path
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James Webb Space Telescope (JWST)
JWST is a 6.5 m IR telescope that will be
launched in 2014. Because of its large mirror, it
will over much better sensitivity and spatial
resolution than any previous IR telescope. It
will focus on the first stars and galaxies, as
well as planets around other stars.
Spitzer
JWST
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Orbit of JWST
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Atacama Large Millimeter/submillimeter Array
(ALMA)
ALMA will be an array of 54m and 12m
millimeter-wave dishes on a high plain (5000 m)
in Chile. It will provide 0.02 resolution at
1mm, which is comparable to JWST. Like JWST,
ALMA will focus on the first galaxies and the
formation of planets.
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The ALMA site
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ALMA science
disk gap created by 5 AU gas giant at 100 pc
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ALMA science
Hubble
Nearby galaxies
Distant galaxies
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ALMA science
ALMA
Nearby galaxies
Distant galaxies
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Square Kilometer Array (SKA)
SKA will be an array of thousands of radio dishes
with a total collecting area of 1 km2 and a
baseline of 3000 km. It will be built in either
Australia or Africa and should begin operations
in 2020. SKA will offer both sharp images (lt0.1)
and a huge field of view (1 deg), as well as 100x
the sensitivity of VLA. SKA will study
interstellar gas from soon after the Big Bang and
the formation of planets.
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SKA design