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Telescopes

Jon HoltzmanNMSU Astronomy

Telescopes are light buckets: bigger buckets collect more light, and faint (far away) objects don’t produce much light!

Why build bigger telescopes?

In principle, bigger telescopes make sharper images:

Why build bigger telescopes?

But, in practice, this doesn’t usually work, because as light comes in through the Earth’s atmosphere, motions and inhomgeneties in our atmosphere blur out images: once you get bigger than several inches in diameter, images don’t get sharper!

So how big do telescopes get? Consider NMSU telescopes:

• The telescopes in the domes are 12 inches (0.3m) in diameter

• The telescope outside is 16 inches (0.4m) in diameter: it collects about twice as much light

Tortugas Mt. Telescope

• Also 24” inches (0.6m) in diameter

• Used a lot in 70’s & 80’s to monitor planets, but hasn’t been used much in last 20 years

• We’re working to renovate and start getting it used again!

Apache Point Observatory

• Observatory operated by NMSU for the Astrophysical Research Corporation

• Four telescopes on site:• 0.5m ARCSAT• 1.0m NMSU• 2.5m SDSS• 3.5m ARC• Small visitor center at nearby National Solar Observatory

ARC 3.5m collects more than 100x the light of the campus observatory telescopes!

Other “medium-sized” telescopes5.0m Hale Palomar Mountain, California4.2 William Herschel Canary Islands, Spain SOAR Cerro Pachon, Chile LAMOST Xinglong Station, China 4.0 Victor Blanco Cerro Tololo, Chile Vista Cerro Paranal, Chile 3.9 AAT NSW, Australia 3.8 Mayall Kitt Peak, Arizona UKIRT Mauna Kea, Hawaii 3.7 AEOS Maui, Hawaii 3.6 "360" Cerro La Silla, Chile. Canada-France-Hawaii Mauna Kea, Hawaii Telescopio Nazionale Galileo, Canary Islands 3.5 MPI-CAHA Calar Alto, Spain New Technology Cerro La Silla, Chile

ARC A pache Point, New Mexico WIYN , Kitt Peak NM

Bigger telescopes: single BIG mirrors

8.3 Subaru Mauna Kea, Hawaii 4100 m NAOJ 8.2 FOUR VLT telescopes Cerro Paranal, Chile 8.1 Gillett Mauna Kea, Hawaii aka Gemini North8.1 Gemini South Cerro Pachon, Chile 6.5 MMT Mt. Hopkins, Arizona 6.5  Walter Baade La Serena, Chile aka Magellan I6.5 Landon Clay aka Magellan II 6.0 Bolshoi Teleskop Azimutalnyi Nizhny Arkhyz, Russia

Bigger telescopes: no longer single pieces of glass!

10.4 Gran Telescopio Canarias La Palma, Canary Islands, 10.0 Keck Mauna Kea, Hawaii ~10 SALT South African Astronomical Observatory 9.2 Hobby-Eberly Mt. Fowlkes, Texas 8.4 -> 12 Large Binocular Telescope Mt. Graham

What about getting sharper images?

Remember, bigger telescope collect more light, but they don’t generally give sharper images because images are blurred as light from objects passes through the Earth’s atmosphere

So what can we do?

Telescopes in Space!Hubble Space Telescope: 2.4m diameter (so not so big), but above the atmosphere sharp images!-> also can observe in ultraviolet light

Another cool idea: “deblur” the atmosphere

New technology uses small “bendable” mirrors to take the atmospheric blur out of the picture.Blur changes fast, so mirrors need to move fast!But need to measure what the blur is first – need a nearby bright starThere aren’t enough bright stars in the sky! So what can you do make your own star!

Telescopes of the future: bigger and sharper!!