Can the Keck Observatory be improved with a third telescope?

Can the Keck Observatory be improved with a third telescope?

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Can the Keck Observatory resolution be improved by adding a third telescope? I imagine that that would be cheaper than building a completely new telescope?

Original Overview

The Keck telescopes mainly work independently of one another. Therefore, adding a third telescope wouldn't really have much of a point (aside from the benefits of having a telescope on top of a mountain with low light pollution and excellent atmospheric conditions). In the past, this might have been a slightly more appealing idea, because the Keck Interferometer (KI) ran from 2003 to 2012, and was a combination of the two telescopes (an effective increase from two 10-meter telescopes to one 85-meter telescope).

KI had some problems, though, that prevented it from living up to its full potential. For instance, four secondary "outrigger" telescopes to improve the interferometer were never built, even though they were an important part of early plans. It was eventually "mothballed" after several of the main scientific objectives were completed. Obviously, the interferometer could be reactivated, but you'd have to make a strong case for doing so. If you could get that to happen, and get permission to build another telescopes, many might choose to use the funds for these outriggers, rather than a whole new instrument.

Finally, building telescopes on Mauna Kea is controversial because of possible environmental impacts, as well as arguments that it endangers Hawaiian cultural and religious sites. There are objections enough over the planned Thirty Meter Telescope, never mind another Keck (which would, admittedly, probably be cheaper, although the two would use different wavelengths).

In short, a third telescope would help only if the interferometer was brought back on line - and even then, you'd have to make a case for both building a new telescope and for choosing it over the original outriggers.


The angular resolution for a single telescope, to an order of magnitude, is $$ hetasimfrac{lambda}{D} ag{1}$$ where $lambda$ is the wavelength of observations and $D$ is the diameter of the dish (adaptive optics, by the way, can make things a bit better). Each Keck telescope has a diameter of $10 ext{ m}$ and observes at the optical and near-infrared ranges - so about $4 imes10^{-7}$ to $4 imes10^{-6} ext{ m}$. This approximation yields angular resolutions of about $0.0083$ to $0.083$ arcseconds. This approximation is accurate to within an order of magnitude.

Likewise, for an interferometer with two telescopes separated by a baseline of distance $b$, the angular resolution is approximately $$ hetasimfrac{lambda}{b}$$ The Keck interferometer had a baseline of $85 ext{ m}$ and observed at wavelengths of $2.2 imes10^{-6}$ to $10^{-5} ext{ m}$. The approximation gives us resolutions of $0.0053$ to $0.024$ arcseconds - pretty close to the actual values.

What if we add a third telescope, identical to the other two and placed in a line next to them, $85 ext{ m}$ from the closer one and $170 ext{ m}$ from the farther one? The longest baseline is now $2 imes85=170 ext{ m}$, twice the baseline of the two-dish setup. We've now made the angular resolution twice as small as before. That's excellent. At $2.2 imes10^{-6} ext{ m}$, the resolution is $1.3 imes10^{-8}$ radians.

Let's think about observations at $2.2 imes10^{-6} ext{ m}$, at the shortest wavelengths the interferometer used. Assume we want to build another telescope with the same angular resolution. Rearranging $(1)$ gives us $$Dsimfrac{lambda}{ heta}$$ Plugging in our numbers ($lambda=2.2 imes10^{-6} ext{ m}$ and $ heta=1.3 imes10^{-8}$ radians), we find that $D$ should be about $170 ext{ m}$ - which is of course the longest baseline of the three-dish interferometer. This is simply implausible at these sort of wavelengths. The largest single-dish optical telescope - observing in shorter wavelengths than this by a factor of about three - is the Gran Telescopio Canarias, at $10.4 ext{ m}$ (although the Large Binocular Telescope is slightly better - $11.8 ext{ m}$).

If you want to use the interferometer at optical wavelengths, you've still looking at a $sim55 ext{ m}$ dish, and that's currently maybe feasible. There are several extremely large telescopes being planned, notably, the Thirty Meter telescope I mentioned earlier and the European Extremely Large Telescope (E-ELT), coming in at around $40 ext{ m}$. The E-ELT should be online as soon as 2-24 (!), which would be fantastic, and would have a comparable resolution to this three-dish interferometer.


Let's look at how much all of this might cost. The E-ELT is expected to cost a little over one billion euros (1.083 billion, to be precise), which comes out to around $1-$1.25 billion, in US dollars (that sounds like a lot, but space-based telescopes can be up to ten times that - though often with higher-quality images). Let's assume that our putative $sim55 ext{ m}$ optical telescope costs $1.5-$2 billion to build.

The cost of the instruments for the Keck Observatory ran about $80 million. This includes the telescopes proper, as well as the cameras and other equipment needed to actually capture the images. Making improvements and other developments has run the total project to about $200 million (not counting observing costs) We can be generous and say that building a third telescope - identical to the other two - and getting the interferometer system up and running might cost $50-$60 million. Maybe that's off, but it certainly can't be wrong by over an order of magnitude. At that point, the entirety of this new Keck Observatory has cost only about one tenth of what a single dish would cost.

Yes, it's likely that I'm wrong somewhere above - that I've made an error in the size of the single-dish telescope, or in estimating the total cost. But the discrepancy is still extraordinary.

Here's the problem, though: Nightly observing costs are high. One night using on Keck telescope costs $54,000. The interferometer uses both telescopes, and, as an article I cited earlier notes,

it's complicated and expensive to link the giant eyes through a system of optical pathways for just a few dozen nights each year.

Interferometry isn't as simply as looking at an object with two different telescopes. It's complicated and costly. If we assume that operating the interferometer would cost around $200,000 per night (is that gratuitous?), we find yearly operating costs of $sim$$73 million - assuming that it's used every night, which isn't likely. But even accounting for all the nights when the interferometer wouldn't be in use, that's probably still more than the estimated yearly costs for the E-ELT (50 million euros, or $54.33 million). The single-dish telescope - again, operating a shorter wavelengths than Keck - would probably cost less per night than the new Keck Interferometer.

Perhaps the relatively low construction costs of the third telescope would offset all of this in the short-term (it likely would).

Here's the really obvious thing, however, that I've been ignoring: More dish means more light. An interferometer with an $170 ext{ m}$ baseline is not the same as a single dish telescope of the same diameter. The three dishes are much, much smaller than the single one. While the resolutions are the same, the size of the dishes really does matter.

A dish with a diameter of $10 ext{ m}$ has an area of $25pi ext{ m}^2$. A dish with a diameter of $170 ext{ m}$ has an area of $7225pi ext{ m}^2$ - a difference of a factor of 289! If you want to make true comparisons between the new interferometer and a large telescope, you'll need more than three dishes. And that will make costs skyrocket.

Just for fun, imagine that we end up having 50 total dishes, with a baseline. If each costs $30 to $40 million to build (and here I'm being generously low), we quickly find that building 48 more dishes runs us to $1.9 billion, or at least the cost of building our $55 ext{ m}$ optical telescope.

Okay, so let's again assume that I made an error somewhere, and this figure is too high. Also, if you ended up building this interferometer (Where would you put it, by the way? Mauna Kea's crowded enough!), you could probably make each dish simpler than Keck I or Keck II. You still have to deal with high nightly operating costs - really high operating costs.


So, why isn't the interferometer up and running? According to NASA, it's because the interferometer's main target, observing certain circumstellar disks, is done:

NASA's primary goal in developing and operating the two 10-m telescope KI was the characterization of faint dust disks around nearby main sequence stars.

For an overview, see Millan-Gabet (2011). As the authors note in section 3, the interferometer's primary observing wavelengths (about $10^{-6}$ to $10^{-7} ext{ m}$, the micrometer range) encompass the peak emission wavelengths of circumstellar dust. Additionally, the resolution at these wavelengths can resolve features of circumstellar disks.

As we determined before, it's hard to build a telescope of comparable resolution operating in the near-infrared. Remember, our single-dish telescope operates largely in the optical range, although it would of course have near-infrared capabilities, to an extent. Therefore, an interferometer like the Keck Interferometer is our best choice - and perhaps our only choice, in the foreseeable future. However, it's certainly possible to build extremely large telescopes operating at slightly shorter wavelengths, with roughly the same angular resolution (to an order of magnitude, really). Plus, they'll gather more light, and - as I found shortly before posting this, in an excellent answer by Rob Jeffries - limitations of interferometer instruments and atmospheric issues makes them less versatile than large, single-dish telescopes.


There are a few takeaways here:

  • Adding a third telescope would give you a resolution unmatched at those wavelengths by any other land-based telescopes.
  • This would likely be a lot cheaper.
  • However, you'd gather only a small fraction of the light that a much larger telescope would.
  • To gather more light, costs would skyrocket - as would technical problems.

So, economically and technically, it's really not feasible to add a third disk to Keck - at least, compared to building a single extremely large telescope.

This is a pretty long answer, and I'm guessing I made an error somewhere. I'll go back and do one more check in the next day or so. If anyone finds one, do let me know!

Third Observatory to Close on Sacred Hawaiian Mountain

A British-built observatory located on Hawaii's tallest mountain announced last week that it would be closing, meeting the request of Hawaii's Gov. David Ige to shut down 25 percent of the telescopes on the mountain, in order to facilitate the construction of the Thirty-Meter Telescope (TMT).

The UKIRT observatory, located on the dormant volcano Mauna Kea, "had already been identified in the Mauna Kea management plan … as one of the telescopes that will not be recycled after the end of its productive life," Guenther Hasinger, director of the Institute for Astronomy at the University of Hawaii, which runs the telescope, told by email.

"This process has been advanced to fulfill Gov. Ige's request for a visibly improved stewardship of the mountain." [Keck Observatory: Cosmic Photos from Hawaii's Mauna Kea]

Done with 'utmost care'

Located on the island of Hawaii, Mauna Kea's high altitude and dry environment make it one of the best sites in the world for astronomical observation. Since the 1960s, 13 observatories have been built on and around the mountaintop.

However, many people in the region also consider Mauna Kea sacred. During the TMT's 2014 groundbreaking ceremony, the telescope attracted significant controversy, and construction was halted earlier this year due to protests, several of which resulted in arrests.

In May, Ige announced a plan to enhance the stewardship of the mountain, calling for the removal of at least 25 percent of the telescopes by the time TMT is ready for operations.

The Caltech Submillimeter Observatory has since closed down operations, while the University of Hawaii at Hilo has initiated the decommissioning process for its Hoku Kea telescope. UKIRT marks the third instrument to announce its closure, meeting the governor's goal.

Formerly known as the United Kingdom Infrared Telescope, UKIRT began operation in 1979. Ownership was transferred to the University of Hawaii in 2014.

"Over the past several years, UKIRT has become one of the most productive telescopes on the globe," Hasinger said. The measurement of productivity is based on the number of publications using UKIRT data and those papers' corresponding impact.

Hasinger said he attributed UKIRT's productivity to a set of very large, specialized imaging sky surveys performed by the telescope that a significant number of researchers use. The telescope has also discovered some of the most distant objects in the universe, the most notable of which is the most distant known quasar, a supermassive black hole that emitted an incredible amount of light when the universe was less than 1 billion years into its total age of 13.8 billion years.

The instrument won't be shut down immediately. Hasinger said that the plan will start some time after the other two telescopes have been decommissioned.

"The general decommissioning process for observatories is outlined in the Office of Mauna Kea Management's Comprehensive Management Plan to ensure that the decommissioning is handled properly and in a culturally and environmentally respectful manner," the University of Hawaii said in a statement.

UKIRT will continue to operate for several years until it is time to begin the shutdown process, which will involve a site deconstruction and removal plan, and a site-restoration plan.

"The whole process needs to be done with utmost care and with public input," Hasinger said.

W. M. Keck Observatory

At Swinburne, we have a remote operations facility in Melbourne that allows our astronomers to remotely control the Keck Obsevatory telescopes from over 9,000 kms away on Mauna Kea, Hawaii. This is the farthest distance from which a telescope of this class has been remotely controlled in real time and is the only such Keck facility outside the mainland of the U.S.A.

Swinburne is the only Australian university with guaranteed access to the world's largest and most productive optical/infra-red telescopes — the twin Keck Observatory telescopes located near the summit of Mauna Kea, Hawaii.

We have an agreement with the California Institute of Technology giving our astronomers unprecedented access to the twin 10-metre Keck Observatory telescopes. Located 4,200 metres above sea level on the dormant volcano Mauna Kea, the Keck telescopes have provided some of the most spectacular views of the universe ever obtained.

The telescopes are the largest and most productive optical/infrared telescopes in the world. Each telescope mirror is made from 36 hexagonal segments 1.8 metres in diameter. The enormous mirror structure weighs in at over 14,000 kg but is extremely well balanced and can be pointed towards objects in the night sky with incredible precision.

To demonstrate the size and iconic hexagonal shape of the Keck mirrors the Centre for Astrophysics and Supercomputing team and students mark out the size of one Keck mirror, with an artist's impression of the footprint.

Keck Observatory instruments

Both Keck I and II offer a wide range of instruments, including:

The Swinburne Time Assignment Committee for Keck (STACK) grants access to the Keck telescopes.

Following a call for proposals, Swinburne astronomers apply to use the telescopes in order to complete their specific astronomy research program. The STACK reviews the applications and grants access to successful applicants.

Most Keck observing runs involve PhD students and some of the data collected forms part of their PhD thesis. Swinburne University of Technology was the first university in Australia to have access to the Keck telescopes. Our PhD students have been using the facility since 2009 for research and training.

“Our unique access to the Keck Observatory has allowed the Centre for Astrophysics & Supercomputing to attract top astronomers, postdoctoral researchers and students from all over the world. CAS is using the Keck Telescopes to push the boundaries of the observable Universe by discovering some of the first galaxies to have formed while also determining how they evolved into the galaxies we see today.

Keck Observatory

Our editors will review what you’ve submitted and determine whether to revise the article.

Keck Observatory, in full W.M. Keck Observatory, astronomical observatory located near the 4,200-metre (13,800-foot) summit of Mauna Kea, a dormant volcano on north-central Hawaii Island, Hawaii, U.S. Keck’s twin 10-metre (394-inch) telescopes, housed in separate domes, constitute the largest optical telescope system of the burgeoning multi-observatory science reserve located on Mauna Kea.

Construction of the Keck Observatory was funded primarily by the W.M. Keck Foundation, a philanthropic organization established by William Myron Keck, founder of Superior Oil Company. The first Keck telescope, Keck I, was completed in 1992 and the second, Keck II, in 1996. The observatory is operated as a consortium led by the California Institute of Technology and the University of California, which created the California Association for Research in Astronomy to maintain and operate the facility. Since 1996 the National Aeronautics and Space Administration (NASA) has participated as a full partner. With the University of Hawaii, which manages the Mauna Kea reserve, they share the use of the facility.

Of Keck Observatory’s overall design, the 10-metre primary mirrors were the most technically challenging components to develop, and their fabrication broke new ground in telescope making. Each mirror consists of 36 hexagonal segments of a special zero-expansion (very low thermal expansion) glass-ceramic material fabricated by Schott Glassworks in Mainz, Germany, and polished by Itek Optical Systems in Lexington, Massachusetts. The individual 1.8-metre- (71-inch-) diameter segments form a mosaic, with each segment continually positioned by three highly precise, computer-controlled actuators such that the entire mirror surface conforms to a hyperboloid with a focal length of 17.5 metres (689 inches). To shape the asymmetrical surface of each off-axis element, Itek opticians developed a technique called stressed mirror polishing, in which the element is deformed in a vise as it is polished when the stress is removed, the element assumes the desired asymmetrical figure.

Each of the telescope optical systems at Keck is mounted in a lightweight, rigid, open-truss framework that moves in altitude and azimuth together to follow the diurnal motion of the heavens. The extremely compact design of the telescopes helped to reduce the size and cost of the domes that house them.

The Keck telescopes embody the kinds of innovations in technology, funding, and management that, beginning in the 1960s, transformed the way large optical instruments are conceived, designed, built, and operated. A system of adaptive optics to counteract the blurring effects of the atmosphere was installed in 1999, and an interferometer that links the light paths of the two telescopes became operational in 2001. With this instrumentation in place the optically integrated telescopes have the resolving power of a single telescope with a mirror 85 metres (3,350 inches) in diameter.

Among the significant discoveries made with the Keck telescopes were the transits of HD 209458 b, the first planet to be seen eclipsing its star. Infrared observations of stars orbiting around the centre of the Milky Way Galaxy demonstrated the presence of a black hole with a mass equivalent to 3,600,000 Suns. Dysnomia, the moon of the dwarf planet Eris, was discovered with the Keck telescopes, and subsequent observations of its orbit showed that Eris is the largest dwarf planet.

Keck Observatory successfully deploys laser system improving resolution and clarity

Image from the launching point of the telescope looking up into the night sky. The central hole in the beam is due to the secondary mirror obscuration on the laser beam launch telescope and is used to align the laser beam. Credit: W. M. Keck Observatory

Hawaii's W. M. Keck Observatory has successfully deployed a $4 million laser system that provides a marked increase in the resolution and clarity of what are already the most scientifically productive telescopes on Earth. The new laser was projected on the sky for the first time on the evening of December 1, 2015 and will allow scientists from around the world to observe the heavens above Maunakea in unprecedented detail.

"The Next Generation Laser System is the third generation of lasers at Keck Observatory, which has been pioneering Laser Guide Star Adaptive Optics on big telescopes since 2001," said Jason Chin, the project manager for the new laser at Keck Observatory.

The first Laser Guide Star Adaptive Optics system on a large telescope was commissioned on the Keck II telescope in 2004 and, among many other firsts, helped reveal the black hole at the center of the Milky Way – one the most significant astronomical discoveries. The second laser system was installed in 2011 on the Keck I telescope, propelling Keck Observatory's lead as the premiere Adaptive Optics research facility in the world. To date more than 240 science results from these laser systems have been published in astronomical journals.

Keck Observatory's Laser Guide Star systems create an artificial star in the earth's mesosphere, at an altitude of roughly 60 miles, by energizing a naturally occurring layer of sodium atoms, causing them to spontaneously emit light (or glow like a star). The adaptive optics system uses this artificial laser guide star to measure the aberrations introduced by turbulence in the earth's atmosphere. A six-inch diameter deformable mirror with 349 actuators is then used to correct for these aberrations at a rate of 1,000 times per second, effectively taking the twinkle out of the stars and providing near-perfect detail for planets, stars and galaxies. Combined with the 10-meter diameter primary mirror, Keck Observatory can offer images with five times the resolution of even the Hubble Space Telescope.

The new laser is the result of a collaboration between Keck Observatory and the European Southern Observatory to develop a more efficient and powerful facility class, commercial laser for astronomy. The new laser, fabricated by TOPTICA in Germany and MPBC in Canada meets both goals handily: the power consumption on the new system is down to 1.2 kW from the previous 80 kW used by the former dye laser system while performance has increased by a factor of ten. Further, the new laser can transition from off to an operational state in five minutes – a dramatic improvement over the five to six hours for the dye laser, which was decommissioned in October to make room for the new laser.

These plots show the symmetry of the artificially created guide star in the mesosphere. Credit: W. M. Keck Observatory

Perhaps most significantly, this is first of the new generation of lasers that all future telescopes are planning on and are looking to Hawaii's findings to build their systems.

Funding for the project came from the Gordon and Betty Moore Foundation, the W. M. Keck Foundation and Friends of Keck Observatory. Initial seed funding was provided by the National Science Foundation.

More than one-third of the budget was spent in Hawaii designing and installing the systems and related infrastructure to support and operate the new laser. The remaining budget was spent on the laser itself – more than $2.5 million. The project also provided infrastructure for adding two additional lasers to support laser tomography in order to determine the distribution of atmospheric turbulence versus altitude. Once funded, the additional lasers can be easily added to the system and would allow a much larger area of the sky to be sampled with even better correction of the atmospheric turbulence.

The W. M. Keck Observatory operates the largest, most scientifically productive telescopes on Earth. The two, 10-meter optical/infrared telescopes near the summit of Maunakea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrographs and world-leading laser guide star adaptive optics systems.

Technique reveals galaxy as it appeared 2 billion years after the Big Bang

Astronomers at the California Institute of Technology (Caltech) and their colleagues used a rare cosmic alignment and modern adaptive optics to image a distant galaxy with similar exquisite resolution promised by the future Thirty Meter Telescope (TMT). This achievement provided detailed insight into the nature of a young star-forming galaxy as it appeared only two billion years after the Big Bang, and determined how that galaxy may eventually evolve to become a system like our own Milky Way.

The team made their observations by coupling two techniques, gravitational lensing --which makes use of an effect first predicted by Albert Einstein in which the gravitational field of massive objects, such as foreground galaxies, bends light rays from objects located a distance behind, thus magnifying the appearance of distant sources -- and laser-assisted guide star (LGS) adaptive optics (AO) on the 10-meter Keck Telescope in Hawaii. Adaptive optics corrects for the blurring effects of Earth's atmosphere by real-time monitoring of the signal from a natural or artificial guide star.

Gravitational lensing enlarged the distant galaxy in angular size by a factor of about eight in each direction. Together with the enhanced resolution using adaptive optics, this allowed the team to determine the internal velocity structure of the remote galaxy, located 11 billion light-years from Earth, and hence its likely future evolution.

The researchers found that the distant galaxy, which is typical in many respects to others at that epoch, shows clear signs of orderly rotation. The finding, in association with observations conducted at millimeter wavelengths, which are sensitive to cold molecular gas (an indicator of galactic rotation), suggests that the source is in the early stages of assembling a spiral disk with a central nucleus similar to those seen in spiral galaxies at the present day.

The research, described in the October 9 issue of the journal Nature, provides a remarkable demonstration of the likely power of the future TMT, the first of a new generation of large telescopes designed to exploit AO.

"This is the most detailed view we have yet seen of a young, early-epoch galaxy, and it has given us unique insight into how such systems begin to take on the familiar characteristics of spiral galaxies like our own Milky Way," said Richard Ellis, Steele Professor of Astronomy at Caltech, co-author of the Nature paper, and a member of the TMT science advisory committee. &ldquoIt is an exciting discovery that heralds the kind of science that will be routine when the Thirty Meter Telescope comes on-line.&rdquo

When completed in the latter half of the next decade, TMT's giant primary mirror and improved optics will produce images with an angular resolution three times better than the 10-meter Keck and 12 times better than the Hubble Space Telescope, at similar wavelengths. Because of the spectacular improvement in angular resolution provided by AO, the TMT will be able to study the internal properties of small distant galaxies, seen as they were when the Universe was young.

Likewise, the Atacama Large Millimeter Array (ALMA), a large interferometer being completed in Chile, will provide a huge step forward in mapping the extremely faint emission from cold hydrogen gas -- the principal component of young, distant galaxies and a clear marker of cold molecular gas -- compared to the coarser capabilities of present facilities. In their recent research, the Caltech-led team has provided an impressive glimpse of what can be done with the superior performance expected of TMT and ALMA.

Using the Hubble Space Telescope, the team located a distinctive galaxy dubbed the "Cosmic Eye" because its form is distorted into a ring-shaped structure by the gravitational field of a foreground galaxy.

"Gravity has effectively provided us with an additional zoom lens, enabling us to study this distant galaxy on scales approaching only a few hundred light-years. This is ten times finer sampling than hitherto possible," explains Postdoctoral Research Scholar Dan Stark of Caltech, leader of the study. "As a result, we can see, for the first time, that a typical-sized young galaxy is spinning and slowly evolving into a spiral galaxy much like our own Milky Way," he says.

The key spectroscopic observations were made with the OSIRIS instrument, developed specifically for the Keck AO system by astrophysicist James Larkin and collaborators at the University of California, Los Angeles. Stark and his co-workers used the OSIRIS instrument to map the velocity across the source in fine detail, allowing them to demonstrate that it has a primitive rotating disk.

To aid in their analysis, the researchers combined data from the Keck Observatory with data taken at millimeter wavelengths by the Plateau de Bure Interferometer (PdBI) located in the French Alps. This PdBI instrument is sensitive to the distribution of cold gas that has yet to collapse to form stars. These observations give a valuable glimpse of what will soon be routine with the ALMA telescope.

"Remarkably, the cold gas traced by our millimeter observations shares the rotation shown by the young stars seen in the Keck observations. The distribution of gas seen with our amazing resolution indicates we are witnessing the gradual build up of a spiral disk with a central nuclear component," explains co-investigator Mark Swinbank of Durham University, who was involved in both the Keck and PBI observations.

This breakthrough demonstrates how important angular resolution has become in ensuring progress in extragalactic astronomy. This will be the key gain of both the TMT and ALMA facilities.

"For decades, astronomers were content to build bigger telescopes, arguing that light-gathering power was the primary measure of a telescope's ability," explains Ellis. "However, adaptive optics and interferometry are now providing ground-based astronomers with the additional gain of angular resolution. The combination of a large aperture and exquisite resolution is very effective for studying the internal properties of distant and faint sources seen as they were when the Universe was young. This is the exciting future we can expect with TMT and ALMA and, thanks to the magnification of a gravitational lens, we have an early demonstration here in this study," he says.

The W. M. Keck Observatory operates twin 10-meter telescopes located on the summit of Mauna Kea. The Observatory, made possible by grants from the W. M. Keck Foundation totaling over $138 million, is managed as a non-profit corporation whose board of directors includes representatives from Caltech and the University of California.

The TMT is currently in the final stages of its design phase. The plan is to initiate construction in 2010 with &lsquofirst light&rsquo in early 2018. This project is a partnership among the California Institute of Technology, the University of California, and ACURA, an organization of Canadian universities. The Gordon and Betty Moore Foundation has provided $50 million for the design phase of the project and has pledged an additional $200 million for the construction of the telescope. ACURA committed an additional $17.5 million for the design and development of TMT. Co-authors on the paper, "The formation and assembly of a typical star-forming galaxies at redshift z

3," are Simon Dye of Cardiff University in Cardiff, Wales Ian R. Smail of Durham University in Durham, England and Johan Richard of Caltech.

Astronomers detect the farthest galaxy yet with Keck telescope

Galaxy EGS8p7, as seen from the Hubble Space Telescope (wide and top right) and Spitzer Space Telescope (inset, bottom right), taken in infrared. Credit: I. Labbé (Leiden University), NASA/ESA/JPL-Caltech

A team of Caltech researchers that has spent years searching for the earliest objects in the universe now reports the detection of what may be the most distant galaxy ever found. In an article published August 28, 2015 in Astrophysical Journal Letters, Adi Zitrin, a NASA Hubble postdoctoral scholar in astronomy, and Richard Ellis—who recently retired after 15 years on the Caltech faculty and is now a professor of astrophysics at University College, London—describe evidence for a galaxy called EGS8p7 that is more than 13.2 billion years old. The universe itself is about 13.8 billion years old.

Earlier this year, EGS8p7 had been identified as a candidate for further investigation based on data gathered by NASA's Hubble Space Telescope and the Spitzer Space Telescope. Using the multi-object spectrometer for infrared exploration (MOSFIRE) at the W.M. Keck Observatory in Hawaii, the researchers performed a spectrographic analysis of the galaxy to determine its redshift. Redshift results from the Doppler effect, the same phenomenon that causes the siren on a fire truck to drop in pitch as the truck passes. With celestial objects, however, it is light that is being "stretched" rather than sound instead of an audible drop in tone, there is a shift from the actual color to redder wavelengths.

Redshift is traditionally used to measure distance to galaxies, but is difficult to determine when looking at the universe's most distant—and thus earliest—objects. Immediately after the Big Bang, the universe was a soup of charged particles—electrons and protons—and light (photons). Because these photons were scattered by free electrons, the early universe could not transmit light. By 380,000 years after the Big Bang, the universe had cooled enough for free electrons and protons to combine into neutral hydrogen atoms that filled the universe, allowing light to travel through the cosmos. Then, when the universe was just a half-billion to a billion years old, the first galaxies turned on and reionized the neutral gas. The universe remains ionized today.

Prior to reionization, however, clouds of neutral hydrogen atoms would have absorbed certain radiation emitted by young, newly forming galaxies—including the so-called Lyman-alpha line, the spectral signature of hot hydrogen gas that has been heated by ultraviolet emission from new stars, and a commonly used indicator of star formation.

Because of this absorption, it should not, in theory, have been possible to observe a Lyman-alpha line from EGS8p7.

"If you look at the galaxies in the early universe, there is a lot of neutral hydrogen that is not transparent to this emission," says Zitrin. "We expect that most of the radiation from this galaxy would be absorbed by the hydrogen in the intervening space. Yet still we see Lyman-alpha from this galaxy."

They detected it using the MOSFIRE spectrometer, which captures the chemical signatures of everything from stars to the distant galaxies at near-infrared wavelengths (0.97-2.45 microns, or millionths of a meter).

"The surprising aspect about the present discovery is that we have detected this Lyman-alpha line in an apparently faint galaxy at a redshift of 8.68, corresponding to a time when the universe should be full of absorbing hydrogen clouds," Ellis says. Prior to their discovery, the farthest detected galaxy had a redshift of 7.73.

One possible reason the object may be visible despite the hydrogen-absorbing clouds, the researchers say, is that hydrogen reionization did not occur in a uniform manner. "Evidence from several observations indicate that the reionization process probably is patchy," Zitrin says. "Some objects are so bright that they form a bubble of ionized hydrogen. But the process is not coherent in all directions."

"The galaxy we have observed, EGS8p7, which is unusually luminous, may be powered by a population of unusually hot stars, and it may have special properties that enabled it to create a large bubble of ionized hydrogen much earlier than is possible for more typical galaxies at these times," says Sirio Belli, a Caltech graduate student who worked on the project.

"We are currently calculating more thoroughly the exact chances of finding this galaxy and seeing this emission from it, and to understand whether we need to revise the timeline of the reionization, which is one of the major key questions to answer in our understanding of the evolution of the universe," Zitrin says.

Keck Discoveries and Observations

More than 25 percent of observations made by US astronomers are done at the Keck Observatory and many of them approach and even surpass the view from the Hubble Space Telescope (which does its observing from high above Earth's atmosphere).

Keck Observatory allows viewers to study objects in visible light and then beyond, into the infrared. That wide range of observation "space" is what makes Keck so scientifically productive. It opens up a realm of interesting objects to astronomers that can't be observed in visible light.

Among them are starbirth regions similar to the familiar Orion Nebula and hot young stars. Not only do the newborn stars glow in visible light, but they heat up the clouds of material that formed their "nests." Keck can peer into the stellar nursery to see the processes of starbirth. Its telescopes allowed observations of one such star, called Gaia 17bpi, a member of a class of hot young stars called "FU Orionis" types. The study helped astronomers gather more information about these newborn stars still hidden in their birth clouds. This one has a disk of material that "falls into" the star in fits and starts. That causes the star to brighten every once in a while, even as it is growing.

At the other end of the universe, the Keck telescopes have been used to observe an extremely distant cloud of gas that existed shortly after the birth of the universe, some 13.8 billion years ago. This distant clump of gas isn't visible to the naked eye, but astronomers could find it using specialized instruments on the telescope to observe a very distant quasar. Its light was shining through the cloud, and from the data, astronomers discovered that the cloud was made of pristine hydrogen. That means it existed at a time when other stars had not yet "polluted" space with their heavier elements. It's a look at conditions back when the universe was only 1.5 billion years old.

Another question that Keck-using astronomers want to answer is "how did the first galaxies form?" Since those infant galaxies are very far away from us and are part of the distant universe, observing them is difficult. First, they are very dim. Second, their light has been "stretched" by the expansion of the universe and, to us, appears in the infrared. Yet, understanding them can help us see how our own Milky Way formed. Keck can observe those distant early galaxies with its infrared-sensitive instruments. Among other things, they can study the light being emitted by hot young stars in those galaxies (emitted in the ultraviolet), which is re-emitted by clouds of gas surrounding the youthful galaxy. This gives astronomers some insight into conditions in those distant stellar cities at a time when they were mere infants, just starting to grow.

Can the Keck Observatory be improved with a third telescope? - Astronomy

The University of California, Berkeley, is part of a new, $20 million project that promises to make ground-based telescopes as powerful as orbiting observatories while dramatically improving the diagnosis and treatment of eye disease and vision correction techniques.

The project proposal, approved July 29 by the National Science Foundation's governing body, the National Science Board, establishes a Center for Adaptive Optics at the University of California, Santa Cruz.

The multi-institutional center, which expects to begin operation in November, is one of five Science and Technology Centers approved for the NSF this year. NSF program guidelines allow for financial commitments of up to $20 million over five years for each center, but the final awards under these cooperative agreements are subject to negotiations between NSF and the lead institutions.

"In astronomy, our needs are for increasingly complex and sophisticated systems, whereas in vision science, the emphasis is likely to be on miniaturization and creating more human-friendly systems for use in health care," said Jerry Nelson, director of the Center for Adaptive Optics and professor of astronomy and astrophysics at UCSC. While at Lawrence Berkeley National Laboratory in the 1980s he designed the twin Keck Telescopes at the W. M. Keck Observatory in Hawaii and is a leading expert on the technology of large telescopes, optics, and instrumentation.

UCSC's 27 partner institutions in the Center for Adaptive Optics will include UC Berkeley, UC San Diego, UCLA, UC Irvine, the University of Chicago, the California Institute of Technology, the University of Rochester, the University of Houston, Indiana University, Lawrence Livermore National Laboratory, and 17 other national laboratory, industry, and international partners.

Adaptive optics is a method to actively compensate for changing distortions that cause blurring of images. It is used in astronomy to correct for the blurring effect of turbulence in the earth's atmosphere and in vision science to compensate for aberrations in the eye that affect vision and impede efforts to study the living retina.

"Up to now astronomers and vision scientists have been working independently on adaptive optics: astronomers to remove the distortion caused by the astmosphere, and optometrists and ophthalmologists to remove distortion caused by the inner parts of the eye," said Marc Davis, professor of astronomy and physics at UC Berkeley. "Now hopefully we can work togeher to develop the next generation of adaptive optics technology."

Other members of the UC Berkeley team are astronomy professors Imke de Pater and James Graham, professor of physics Bernard Sadoulet, and professor of electrical engineering and computer sciences Richard Muller, an expert on MEMS (microelectromechanical systems).

An adaptive optics (AO) system requires several highly advanced technologies, including precision optics, sensors, and deformable mirrors, plus high-speed computers to integrate and control the whole system. Basically, the AO system uses a point source of light as a reference beacon to measure precisely the distortion created by the atmosphere (or by internal imperfections and fluids in the eye) then an "adaptive optical element," usually a deformable mirror, is used to cancel the effect by applying an opposite distortion. For astronomy, the system must measure atmospheric distortion and apply a correction hundreds of times per second.

First-generation adaptive optics systems have been installed on the 3-meter Shane Telescope at Lick Observatory and the 10-meter Keck II Telescope in Hawaii. Although these systems have yielded impressive results, AO is not yet in routine use, Nelson said.

"Adaptive optics is enormously complex, and to bring this technology to maturity and make AO systems practical tools for scientists will require a coherent national program that brings together scientists and engineers with diverse areas of expertise," Nelson said.

"As far as we've come in adaptive optics, we've only just begun to realize its potential," said Joseph Miller, director of UCO/Lick.

For astronomers, adaptive optics can give ground-based telescopes the same clarity of vision that space telescopes achieve by orbiting above earth's turbulent atmosphere.

"This is the gateway to an unimaginable future," said UCSC astronomer Sandra Faber. "Adaptive optics makes the Keck Telescope 20 times sharper, so it's like bringing the universe 20 times closer," she said.

With adaptive optics, the Keck Telescopes, currently the largest optical telescopes in the world, can achieve four times the resolution of the Hubble Space Telescope in the near-infrared wavelengths, noted Claire Max, who heads the group at Lawrence Livermore National Laboratory (LLNL) that helped developed the AO systems for the Keck and Lick Observatories.

Max said she expects most of the large ground-based telescopes will have AO systems within the next few years. Very few astronomers, however, have any experience using adaptive optics, she said. "One goal of the center is to bring adaptive optics to the broader astronomical community through conferences and workshops," said Max, who is director of university relations for LLNL.

In vision science, adaptive optics has made it possible to obtain images of the living human retina with unprecedented resolution, enabling researchers to see the individual receptors involved in vision, said David Williams, director of the Center for Visual Science at the University of Rochester. Williams and his coworkers recently used AO to obtain images showing how the three types of cones involved in color vision are arranged in the human retina.

"We've also just begun to explore the potential of adaptive optics for looking at retinal diseases," Williams said. "In addition, by measuring aberrations in the eye better than before, we may be able to develop better contact lenses or better laser surgery procedures. So this technology has a lot of potential for improving vision."

While astronomy and vision science use similar AO technology, they have different needs for future technology development, Nelson said. "In astronomy, our needs are for increasingly complex and sophisticated systems, whereas in vision science the emphasis is likely to be on miniaturization and creating more human-friendly systems for use in health care," he said.

The Center for Adaptive Optics will provide the sustained effort needed to bring adaptive optics from promise to widespread use. The center will conduct research, educate students, develop new instruments, and disseminate knowledge about adaptive optics to the broader scientific community. The center will concentrate on astronomical and vision science applications and will reach out to scientists in other fields to share technologies.

The center will also develop a range of science education and outreach programs, which will be coordinated with UCSC's existing programs through the campus's Educational Partnership Center. Partnerships are planned with local public schools and with institutes such as the Chabot Observatory and Science Center in Oakland, which operates a planetarium, after-school science programs for youth, training for teachers, and summer science camps. In the Chicago area, the center will work with similar programs through the Adler Planetarium and the Yerkes Observatory.

"Everyone involved in the center will devote some of their time to education and outreach programs," Nelson said.

Industry partnerships will be important for developing practical new devices and implementing adaptive optics applications in health care and other fields. Bausch and Lomb, ERIM International, and Lucent Technologies will be among the center's industrial partners.

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