astronomy

Large Binocular Telescope

Large Binocular Telescope is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Large Binocular Telescope rather than just read about it. In short: The Large Binocular Telescope (LBT) is an optical telescope for astronomy located on 10,700-foot (3,300 m) Mount Graham, in the Pinaleno Mountains of southeastern Arizona, United States. It is a part of the Mount Graham International Observatory.

Key takeaways

Large Binocular Telescope belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Large Binocular Telescope to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Large Binocular Telescope from memory before moving on to harder problems.

Reference excerpt

The Large Binocular Telescope (LBT) is an optical telescope for astronomy located on 10,700-foot (3,300 m) Mount Graham, in the Pinaleno Mountains of southeastern Arizona, United States. It is a part of the Mount Graham International Observatory. When using both 8.4 m (330 inch) wide mirrors, with centres 14.4 m apart, the LBT has the same light-gathering ability as an 11.8 m (464 inch) wide single circular telescope and the resolution of a 22.8 m (897 inch) wide one. The LBT mirrors individually are the joint second-largest optical telescope in continental North America, next to the Hobby–Eberly Telescope in West Texas. It has the largest monolithic, or non-segmented, mirror in an optical telescope. Strehl ratios of 60–90% in the infrared H band and 95% in the infrared M band have been achieved by the LBT.

Project The LBT was originally named the "Columbus Project". It is a joint project of these members: the Italian astronomical community represented by the Istituto Nazionale di Astrofisica, the University of Arizona, University of Minnesota, University of Notre Dame, University of Virginia, the LBT Beteiligungsgesellschaft in Germany (Max Planck Institute for Astronomy in Heidelberg, Landessternwarte in Heidelberg, Leibniz Institute for Astrophysics Potsdam (AIP), Max Planck Institute for Extraterrestrial Physics in Munich and Max Planck Institute for Radio Astronomy in Bonn); Ohio State University; and the Research Corporation for Science Advancement based in Tucson, Arizona, USA. The cost was around 100 million euro. The telescope design has two 8.4 m (330 inch) mirrors mounted on a common base, hence the name "binocular". LBT takes advantage of active and adaptive optics, provided by Arcetri Observatory. The collecting area is two 8.4 meter aperture mirrors, which works out to about 111 m2 combined. This area is equivalent to an 11.8-meter (460 in) circular aperture, which would be greater than any other single telescope, but it is not comparable in many respects since the light is collected at a lower diffraction limit and is not combined in the same way. Also, an interferometric mode will be available, with a maximum baseline of 22.8 meters (75 ft) for aperture synthesis imaging observations and a baseline of 15 meters (49 ft) for nulling interferometry. This feature is along one axis with the LBTI instrument at wavelengths of 2.9–13 micrometres, which is the near infrared. The telescope was designed by a group of Italian firms, and assembled by Ansaldo in its Milanese plant.

Mountain controversy

The choice of location sparked considerable local controversy, both from the San Carlos Apache Tribe, who view the mountain as sacred, and from environmentalists who contended that the observatory would cause the demise of an endangered subspecies of the American red squirrel, the Mount Graham red squirrel. Environmentalists and members of the tribe filed some forty lawsuits – eight of which went before a federal appeals court – but the project ultimately prevailed after an act of the United States Congress. The telescope and mountain observatory survived two major forest fires in thirteen years, the more recent in the summer of 2017. Likewise the squirrels continue to survive. Some experts now believe their numbers fluctuate dependent upon nut harvest without regard to the observatory.

First light

The telescope was dedicated in October 2004 and saw first light with a single primary mirror on October 12, 2005, which viewed NGC 891. The second primary mirror was installed in January 2006 and became fully operational in January 2008. The first light with the second primary mirror was on September 18, 2006, and for the first and second together it was on January 11–12, 2008. The first binocular light images show three false-color renditions of the spiral galaxy NGC 2770. The galaxy is 88 million light years from the Milky Way galaxy, a relatively close neighbor. The galaxy has a flat disk of stars and glowing gas tipped slightly toward Earth's line of sight. The first image taken combined ultraviolet and green light, and emphasizes the clumpy regions of newly formed hot stars in the spiral arms. The second image combined two deep red colors to highlight the smoother distribution of older, cooler stars. The third image was a composite of ultraviolet, green and deep red light and shows the detailed structure of hot, moderate and cool stars in the galaxy. The cameras and images were produced by the Large Binocular Camera team, led by Emanuele Giallongo at the Rome Astrophysical Observatory. In binocular aperture synthesis mode LBT has a light-collecting area of 111 m2, equivalent to a single primary mirror 11.8-meter (39 ft) in diameter, and will combine light to produce the image sharpness equivalent to a single 22.8-meter (75 ft) telescope. However, this requires a beam combiner that was tested in 2008, but has not been a part of regular operations. It can take images with one side at 8.4 m aperture, or take two images of the same object using different instruments on each side of the telescope.

Adaptive optics

In the summer of 2010, the "First Light Adaptive Optics" (FLAO) – an adaptive optics system with a deformable secondary mirror rather than correcting atmospheric distortion further downstream in the optics – was inaugurated. Using one 8.4 m side, it surpassed Hubble sharpness (at certain light wavelengths), achieving a Strehl ratio of 60–80% rather than the 20–30% of older adaptive optic systems, or the 1% typically achieved without adaptive optics for telescopes of this size. Adaptive optics at a telescope's secondary (M2) was previously tested at MMT Observatory by the Arcetri Observatory and University of Arizona team.

In the media The telescope has made appearances on an episode of the Discovery Channel TV show Really Big Things, National Geographic Channel Big, Bigger, Biggest, and the BBC program The Sky At Night. The BBC Radio 4 radio documentary The New Galileos covered the LBT and the James Webb Space Telescope.

Discoveries and observations LBT, with the XMM-Newton, was used to discover the galaxy cluster 2XMM J083026+524133 in 2008, over 7 billion light years away from Earth. In 2007 the LBT detected a 26th magnitude afterglow from the gamma ray burst GRB 070125. In 2017, LBT observed the OSIRIS-REx spacecraft, an uncrewed asteroid sample return spacecraft, in space while it was en route.

Instruments

Some current or planned LBT telescope instruments:

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Large Binocular Telescope

Start with the simplest possible case. Write down what Large Binocular Telescope claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Large Binocular Telescope before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Large Binocular Telescope ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Large Binocular Telescope

In research: Large Binocular Telescope appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Large Binocular Telescope in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Large Binocular Telescope is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2004 establishments in Arizona, Astronomical observatories in Arizona, Buildings and structures in Graham County, Arizona, so understanding it makes those chapters shorter.
In everyday life: Look for Large Binocular Telescope outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Large Binocular Telescope in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Large Binocular Telescope means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Large Binocular Telescope out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Large Binocular Telescope in simple terms?

Why does Large Binocular Telescope matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Large Binocular Telescope?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Large Binocular Telescope.