{ Telescopes Jon Holtzman NMSU 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” telescopes 5.0mHale Palomar Mountain, California 4.2 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 NAOJSubaruNAOJ 8.2 FOUR VLT telescopes Cerro Paranal, ChileCerro Paranal 8.1 Gillett Mauna Kea, Hawaii aka Gemini NorthGillett 8.1 Gemini South Cerro Pachon, ChileCerro Pachon 6.5 MMT Mt. Hopkins, ArizonaMMT 6.5 Walter Baade La Serena, Chile aka Magellan I6.5 Landon Clay aka Magellan IIWalter Baade6.5 Landon Clay 6.0 Bolshoi Teleskop Azimutalnyi Nizhny Arkhyz, RussiaBolshoi Teleskop Azimutalnyi

Bigger telescopes: no longer single pieces of glass! 10.4 Gran Telescopio Canarias La Palma, Canary Islands, 10.0 Keck Mauna Kea, HawaiiGran Telescopio CanariasKeckMauna Kea ~10 SALT South African Astronomical ObservatorySALTSouth African Astronomical Observatory 9.2 Hobby-Eberly Mt. Fowlkes, TexasHobby-Eberly 8.4 -> 12 Large Binocular Telescope Mt. GrahamLarge Binocular TelescopeMt. 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 star There aren’t enough bright stars in the sky! So what can you do  make your own star!

Telescopes of the future: bigger and sharper!!