Download Angular resolution

Telescopes continued…
Why is bigger better?
Two reasons…
(1) Light-gathering power
• Depends on the area of the objective
mirror (or lens)
• Compare 16-inch to our 10-inch scopes:
(2) Resolution of telescopes
• Angular resolution depends on telescope
diameter (D) and signal wavelength (λ):
Rayleigh criterion: Θmin ~ λ / D
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.
Kitt Peak National Observatory
Mayal 4-m
Wynn
•Near Tucson
•Tax supported
with other
consortia, too
•Nice public
program
•Tucson: good
lighting
McMath solar
telescope
Mayal 4-meter
McMath solar telescope
The MMT (Mt. Hopkins, SE AZ)
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 ….
New MMT 6.5-meter
Also on Hopkins: LBT
• Large Binocular
Telescope
• Twin 8.4-m
mirrors
• Optical
interferometry
• Will image
extrasolar
planets
And: VATT & SMT
• Vatican Advanced
Technology
Telescope
• Univ. Arizona SubMillimeter
Telescope
Mauna Kea , Hawaii – Keck, Gemini, Suabaru, NASA,
and others
Gemini (North) 8-m Telescope
…
8-meter spin-cast mirror
Twin Keck 10-m Telescopes
Keck segmented primary mirror
European Southern Observatory (Chile)
VLT four 8-m’s
Why the shift to southern hemisphere?
European Southern
Observatory 3.6-m
Cerro Tololo nearby with the Blanco 4-m, a twin to Kitt Peak 4-m
DuPont 2.5-m
also there
Supporting this closed Mt. Wilson
100-inch
Gemini South and SOAR on nearby Cerro Pachỏn
Gemini South
SOAR = Southern Observatory for Astrophysical
Research
UNC-CH (17%)
and others
How’s it coming?...
PROMPT …