Category: Observatories

Today, the world of astronomy meets the science fiction world of Isaac Asimov’s “I, Robot” with the commissioning of a new robotic telescope. While it lacks the humanoid qualities of the movie version, this robot will aid in humanity’s quest to understand the early universe by observing the most distant and powerful explosions known.

Located at the Fred L. Whipple Observatory on Mt. Hopkins, Arizona, the Peters Automated Infrared Imaging Telescope (PAIRITEL) is the first fully “robotic” infrared telescope in North America dedicated to observing transient astronomical events. The telescope, used for several years in a major all-sky survey (2MASS), has been refurbished to work autonomously. It will operate in tandem with NASA’s new gamma-ray burst satellite “Swift,” to be launched on November 8 from Kennedy Space Center.

With PAIRITEL, a team of astronomers led by Dr. Joshua Bloom of the Harvard Society of Fellows, Harvard-Smithsonian Center for Astrophysics (CfA) and UC Berkeley, hopes to pinpoint the gamma-ray burst explosions from the first and most distant stars in the universe. A gamma ray burst (GRB) is a quick flash of gamma-ray radiation lasting about a minute, accompanied by an afterglow emission of X-rays, visible, infrared, and radio light. The afterglow may be observable for days to weeks afterward. The majority of GRBs are believed to be due to massive stars that explode violently and release tremendous blasts of energy.

“Innovatively exploring the night sky in the time domain – seeing how things change from night to night, and even from minute to minute – is the next big frontier in astronomy,” said Bloom. “PAIRITEL was optimized to study cosmic events like GRBs that are here today and gone tomorrow.”

Peering back to a time when the universe was less than 1 billion years old is the holy grail of observational astronomy. So far, only energetic galaxy cores known as quasars have been used to probe the early universe. But gamma-ray burst afterglows, if astronomers are able to image them quickly, hold clear advantages over quasars. For up to one hour after the burst, afterglow brightnesses can reach up to 1000 times that of the brightest known quasar in the universe.

Also, explained Bloom, “The stars that create GRBs likely formed before the black holes that create quasars. So by looking for the youngest and most distant GRBs, we can study the earliest epochs of the universe.”

A key feature of PAIRITEL that will allow the location of distant GRBs is its rapid response time. PAIRITEL will receive signals from Swift and automatically move, in under 2 minutes, to the part of the sky where a GRB has appeared.

“My ultimate vision is to have astronomy robots talking to robots, deciding what to observe and how, with no human intervention,” said Bloom. “As it is, PAIRITEL only e-mails us when it’s found a particularly interesting source, or when something goes wrong and it needs help!”

Another key feature of PAIRITEL is its sensitivity at infrared wavelengths, setting this system apart from the bevy of visible-light robotic telescopes already in existence. Images taken with infrared filters (about twice the wavelength of visible light) are indispensable: visible light emitted from more than 12 billion light-years away is completely extinguished for observers on Earth. Bloom explained, “Forget about the dimming due to the extreme distances: the hydrogen gas between us and the explosions makes it like searching for a firefly behind a thick London fog. In the infrared we can peer through the shroud to the good stuff.” In addition, the unique camera on PAIRITEL takes pictures simultaneously at three different wavelengths of light, allowing for instantaneous full-color snapshots.

The Swift spacecraft will find GRBs at a rate 10 to 20 times higher than currently feasible, and should find more bursts in 6 months than all well-studied bursts to date. Bloom said he is most excited about using Swift and PAIRITEL “together to find the golden needle in the haystack – a high-redshift GRB that’s farther away than the most distant known galaxy or quasar.”

When PAIRITEL is not chasing down GRBs, it will be used to make precision measurements of supernovae to help determine the few fundamental parameters that dictate the expansion of the universe. Among other projects, Dr. Michael Pahre (CfA) will use PAIRITEL to study the near-infrared light of nearby galaxies to compare it with mid-infrared light in images obtained with NASA’s Spitzer Space Telescope. Harvard graduate student Cullen Blake, who has written software for the project, will also use PAIRITEL to try to find Earth-mass planets around brown dwarfs. Other PAIRITEL team members include: Prof. Mike Skrutskie (Univ. of Virginia), Dr. Andrew Szentgyorgyi (CfA), Prof. Robert Kirshner (Harvard University/CfA), Dr. Emilio Falco (CfA), Dr. Thomas Matheson (NOAO), and Dan Starr (Gemini Observatory, Hawaii). The staff of Mt. Hopkins-Wayne Peters, Bob Hutchins, and Ted Groner-worked on the automation of the telescope.

PAIRITEL, nearly 2 years after the inception of the project, is being dedicated today to the late Jim Peters, who worked for the Smithsonian Astrophysical Observatory, first on satellite tracking and then as a telescope operator on Mt. Hopkins for 25 years. His widow and son will be in attendance at the ceremony.

The project was funded by a grant from the Harvard Milton Fund. The telescope is owned by the Smithsonian Astrophysical Observatory and the infrared camera is on loan from the University of Virginia.

Additional information about Swift and PAIRITEL is available online at:

http://swift.gsfc.nasa.gov/docs/swift/swiftsc.html
http://pairitel.org/

Original Source: CfA News Release

European and US radio astronomers have demonstrated a new way of observing the Universe – through the Internet!

Using cutting-edge technology, the researchers have managed to observe a distant star by using the world’s research networks to create a giant virtual telescope. The process has allowed them to image the object with unprecedented detail, in real-time; something which only a few years ago would have been impossible. The star chosen for this remarkable demonstration, called IRC+10420, is one of the most unusual in the sky. Surrounded by clouds of dusty gas and emitting strongly in radio waves, the object is poised at the end of its life, heading toward a cataclysmic explosion known as a ‘supernova’.

These new observations give an exciting glimpse of the future of radio astronomy. Using research networks, not only will radio astronomers be able to see deeper into the distant Universe, they’ll be able to capture unpredictable, transient events as they happen, reliably and quickly.

Astronomers are always seeking to maximise the resolution of their telescopes. Resolution is a measure of the amount of detail it can pick out. The bigger the telescope, the better the resolution. VLBI (or Very Long Baseline Interferometry) is a technique used by radio astronomers to image the sky in supreme detail. Instead of using a single radio dish, arrays of telescopes are linked together across whole countries or even continents. When the signals are combined in a specialised computer, the resulting image has a resolution equal to that of a telescope as large as the maximum antenna separation.

In the past, the VLBI technique was severely hampered because the data had to be recorded onto tape and then shipped to a central processing facility for analysis. Consequently, radio astronomers were unable to judge the success of their endeavours until many weeks, even months, after the observations were made. The solution, to link the telescopes electronically in real-time, enables astronomers to analyse the data as it happens. The technique, naturally called e-VLBI, is only possible now that high-bandwidth network connectivity is a reality.

The recent 20-hour long observations, performed on 22nd September using the European VLBI Network (EVN), involved radio telescopes in the UK, Sweden, the Netherlands, Poland and Puerto Rico. The maximum separation of the antennas was 8200 km, giving a resolution of at least 20 milliarcseconds (mas); this is about 5 times better than the Hubble Space Telescope (HST). This level of detail is equivalent to picking out a small building on the surface of the moon! The inclusion of the antenna at Arecibo, in Puerto Rico, also increased the sensitivity of the telescope array by a factor of 10. Even so, observing at a frequency of 1612 MHz, the signal from the distant star was more than a billion billion times weaker than a typical mobile phone handset!

Each telescope was connected to its country’s National Research and Education Network (NREN), and the data routed at 32 Mbits/second per telescope through GEANT, the pan-European research network, to SURFnet, the Dutch network. The data were then delivered to the Joint Institute for VLBI in Europe (JIVE), the central processing facility for the EVN in the Netherlands. There, the 9 Terabits of data were fed in real-time into a specialised supercomputer, called a ‘correlator’, and combined. The same research networks were then used to deliver the final data product directly to the astronomers who formed the image. Until the network infrastructure provided GEANT became available, astronomers were unable to transfer the huge amounts of data required for e-VLBI across the Internet. In a very real sense, the Internet itself acts like a telescope, performing the same job as the curved surfaces of the individual radio dishes. Dai Davies, General Manager of DANTE who operate GEANT, said “e-VLBI performed successfully on an intercontinental basis demonstrates in the clearest possible terms the importance of data communications networks to modern science. Research networking is fundamental to this new radio astronomy technique and it is very satisfying indeed to see the benefits that are now resulting from it”.

Although the scientific goals of the experiment were modest, these e-VLBI observations of IRC+10420 open up the possibility of watching the structures of astrophysical objects as they change. IRC+10420 is a supergiant star in the constellation of Aquila. It has a mass about 10 times that of our own Sun and lies about 15,000 light years from Earth. One of the brightest infrared sources in the sky, it is surrounded by a thick shell of dust and gas thrown out from the surface of the star at a rate of about 200 times the mass of the Earth every year. Radio astronomers are able to image the dust and gas surrounding IRC+10420 because one of the component molecules, hydroxyl (OH), reveals itself by means of strong ‘maser’ emission. Essentially, the astronomers see clumps of gas where radio emission is strongly amplified by special conditions. With the zoom lens provided by e-VLBI, astronomers can make images with great detail and watch the clumps of gas move, watch masers being born and die on timescales of weeks to months, and study the changing magnetic fields that permeate the shell. The results show that the gas is moving at about 40 km/s and was ejected from the star about 900 years ago. As Prof. Phil Diamond, one of the research team at Jodrell Bank Observatory (UK), explained, “the material we’re seeing in this image left the surface of the star at around the time of the Norman Conquest of England”.

It is believed IRC+10420 is rapidly evolving toward the end of its life. At some point, maybe thousands of years from now, maybe tomorrow, the star is expected to blow itself apart in one of the most energetic phenomena known in the Universe – a ‘supernova’. The resulting cloud of material will eventually form a new generation of stars and planetary systems. Radio astronomers are now poised, with the incredible power of e-VLBI, to catch the details as they happen and study the physical processes that are so important to the structure of our Galaxy and to life itself.

The emergent technology of e-VLBI is set to revolutionise radio astronomy. As network bandwidths increase, so too will the sensitivity of e-VLBI arrays, allowing clearer views of the furthest and faintest regions of space. Dr Mike Garrett, JIVE Director, commented, “These results provide a glimpse of the enormous potential of e-VLBI. The rapid progress in global communications networks should permit us to connect together the largest radio telescopes in the world at speeds exceeding tens of Gigabits per second over the next few years. The death throes of the first massive stars in the Universe, the emerging jets of matter from the central black-holes of the first galaxies, will be revealed in exquisite detail.”

Original Source: Jodrell Bank News Release

Thirty Metre Optical and Infrared ground-based telescopes should be seeing first light in about 2011, and be fully operational by 2015. Four such instruments are in the works, CalTech?s TMT, Gemini?s GSMT, Canada?s VLOT, and Europe?s ELT. With 100 times the speed of Hubble, and three times the resolution of the Keck instruments, these tools will help unlock some new keys to our understanding the cosmos.

Earth-based thirty-metre telescopes are being funded, and designed now. Caltech’s TMT project will undergo design reviews in 2006 and 2007 with full construction funding scheduled to be given by the Gordon and Betty Moore Foundation in July 2008. Gordon Moore [of Moore?s Law fame] was the founder of Intel. His foundation supplied a 17 million dollar grant to design the TMT in October 2003. In total the instrument is expected to cost about 800 million dollars.

Adaptive optics have proved a tremendous success, and are one reason that there will be no replacement for the Hubble telescope as a space based tool for covering the optical and near infrared part of the spectrum. These three instruments will be getting first light with some segments about the same time that the 6.5 metre James Webb Space Telescope will begin its science mission in 2011-2.

Robert Gilmozzi?s OverWhelmingly Large Telescope [OWL project] is also trying to get first light by 2015, but faces more financial and technical obstacles than the 30-meter instruments. If the OWL doesn?t get built in this go-around, similar designs will likely be used for the following decade.

These instruments will be able to perform many tasks that the current generation of instruments either can?t do, or would require prohibitive amounts of observing time to accomplish including the following:

• Map the density and heavy element content of the intergalactic media from nearby to beyond z=1.5 by measuring the details absorption spectra of 100,000 QSOs.
• Observe the galaxy formation process by studying the movement of ionized gas clouds from z=3 to 8. Note these instruments can discern sources as close as 150 parsecs apart at z=3.
• Chart the distortion of images of background galaxies when looking through galactic clusters to map the presence of dark matter to an unprecedented level of detail.
• Chart the star populations of nearby galaxies observing element abundances, and determining formation histories.
• Observe planet formation around the nearest thousand new stars. This instrument will be able to resolve to 0.4AU when looking at objects 33 light-years away.
• Detect and characterize mature planets around nearby stars.

Caltech just put up a job posting for an Observatory Scientist for the TMT project. The Thirty metre telescopes are on their way.

Written by John A. Cross

Australian researchers have shown that a ground-based telescope in Antarctica can take images almost as good as those from the Hubble Space Telescope, at a fraction of the cost.

“It represents arguably the most dramatic breakthrough in the potential for ground-based optical astronomy since the invention of the telescope,” says University of New South Wales Associate Professor Michael Ashley, who co-authored the Nature paper. “The discovery means that a telescope at Dome C on the Antarctic plateau could compete with a telescope two to three times larger at the best mid-latitude observatories, with major cost-saving implications. Dome C could become an important ‘test-bed’ for experiments and technologies that will later be flown as space missions. Indeed, for some projects, the site might be an attractive alternative to space based astronomy.”

Astronomical observations made by Australian astronomers at Dome C on the Antarctic Plateau, 3250 m above sea-level, prove that the site has less “star jitter” than the best mid-latitude observatories in Hawaii, Chile and the Canary Islands. While Antarctica has long been recognised as having characteristics that make it a potentially excellent site for astronomy, seeing conditions at the South Pole itself (latitude 90 degrees south) are poor due to atmospheric turbulence within 200 – 300 m of the ground.

By contrast, Dome C, located at latitude 75 degrees south, has several atmospheric and site characteristics that make it ideal for astronomical observations. The site’s atmospheric characteristics include low infrared sky emission, extreme cold and dryness, a high percentage of cloud free time, and low dust and aerosol content – features that confer significant benefits for all forms of astronomy, especially infrared and sub-millimetre.

Dome C is 400 m higher than the South Pole and further inland from the coast. Being a “dome” – a local maximum in the elevation of the terrain – it experiences much lower peak and average wind speeds, which has a profound beneficial effect on the performance of astronomical instruments. Like other regions on the Antarctic plateau, it shares the advantages of a lack of seismic activity and low levels of light pollution.

A key issue in considering where to locate new generation ground-based optical telescopes is to choose a site with excellent ‘seeing’. Seeing is defined as the amount of star jitter or sharpness of astronomical images, which is affected by atmospheric conditions close to Earth.

“The sharpness of the astronomical images at Dome C is two to three times better than at the very best sites currently used by astronomers, including those in Chile, Hawaii and the Canary Islands,” says A/Prof Ashley. “This implies a factor of ten increase in sensitivity. Put another way, an 8 metre infrared telescope on the Antarctic Plateau could achieve the sensitivity limits of a hypothetical 25 metre telescope anywhere else.

“It means there’s now a fantastic opportunity now for Australian astronomers to build world-beating telescopes at the site. I expect the romance and adventure of this combination of astronomy and Antarctica will inspire the next generation of young scientists.”

The observations at Dome C represent a stunning technical achievement, according to the paper’s lead author, Dr Jon S. Lawrence, a University of New South Wales Postdoctoral Fellow.

“We set up a self contained robotic observatory called AASTINO (Automated Astronomical Site Testing International Observatory) at Dome C in January 2004. Powered by two engines, the facility has heat and electrical power that allowed us to communicate with site testing equipment, computers and telescopes via an Iridium satellite network. The entire experiment was controlled remotely — we didn’t turn the telescope on until we returned home,” says Dr Lawrence. “When we left there in February we said goodbye to it knowing all that we could do was communicate with it by the phone and the Internet. If we’d needed to press a reset button on a computer or something, there was no way to do so, and the entire experiment could have failed.

“As it turns out, we’ve made some exceptional findings and published a paper in Nature before even returning to the site. We’re pretty thrilled about it.”

Original Source: UNSW News Release

The project plans are being developed by a consortium of institutions headed up by Cornell, and funded by the National Science Foundation among others. The SKA plans are loosely based on the ideas being implemented by the Allen Telescope Array (ATA). The ATA is an array of 350 six meter dishes funded by Microsoft philanthropist Paul Allen specifically for SETI research. Note that the science and technology for using interferometers for radio has now reached a stage where this instrument can be built. While this transcontinental technique may be employable for microwaves in the decades ahead, infrared, optical, and x-ray interferometers (several connected telescopes) still require a short direct path of the light to follow, so that the images can be combined using optical, not electronic, means.

The 1.4 billion dollar SKA project should have a final design, and locations defined by 2007, with construction beginning by 2010, and it should be complete and operational by 2015. The array itself will have a core central array of 3300 dishes, and 160 outlying stations of about 7 dishes each covering a broad area of North and Central America.

When complete this tool will have the sensitivity of a single dish, 800 meters in diameter, which is on the order of a hundred times more sensitive than any steerable dish on the planet today. It is also about ten times the sensitivity of the giant dish at Arecibo, which is also operated by Cornell. At its shortest wavelength, the array will be able to image sources to a scale of 500 micro-arcseconds, which is about 15 light-years at the Andromeda galaxy [M31], or a few hundred AU when mapping nearby molecular clouds in our own galaxy.

With all this new detection capability will come a great deal of new science. This month, peer review journals and other sources are getting ready to print numerous papers proposing work that can be done with this instrument. Some of the science goals will help us observe the universe before the first stars formed, and will answer detailed questions about an epoch much earlier than will be seen by the upcoming James Webb Space Telescope. Among the science goals are: Mapping the star formation history and large-scale structure of the Universe, tracing the star formation history over cosmological time, and studying of the Sunyaev-Zel’dovich effect at high redshifts, which some say may have contaminated observed Cosmic Microwave background radiation, and altered the apparent age and dark matter density of the universe. Many of these observations will be done looking at the highly redshifted 21-cm line from neutral hydrogen.

Other science goals include tracing out the magnetic field structure in parsec to Megaparsec jets, in normal galaxies and in distant clusters of galaxies, as well as locate distant (z > 2) clusters, probing strong gravitational fields and the cosmological evolution of super-massive black holes, identifying radio transients 100 times fainter than we can now see, probing the scintillating universe and exploiting super-resolution phenomena, identifying the overall structure, discrete components, and turbulent and magnetic properties of the Milky Way and nearby galaxies, a Milky Way census of faint old pulsars and other compact objects, searching for brown dwarfs in the local Galactic environs and mapping thermal emission from nearby stars, as well as inventorying and tracking solar system debris such as asteroids, comets, and KBOs.

A recent paper points out that the SKA can be used to receive data rates hundreds of times faster than the current Deep Space Network from very distant space probes for short periods, such as from the ESA?s proposed tiny Pluto Orbiter Probe, or NASA?s New Horizons mission to the Kuiper belt.

The SKA will be a versatile instrument with capabilities far beyond what are available in today?s instruments. For radio astronomy, the SKA is the shape of things to come.

Links:
SKA site
SKA Design strawman paper
Allen Telescope Array website

Author: John A. Cross

British astronomers are celebrating a world first that could revolutionise the future of astronomy. They have just begun a project to operate a global network of the world’s biggest robotic telescopes, dubbed ‘RoboNet-1.0’ which will be controlled by intelligent software to provide rapid observations of sudden changes in astronomical objects, such as violent Gamma Ray Bursts, or 24-hour surveillance of interesting phenomena. RoboNet is also looking for Earth-like planets, as yet unseen elsewhere in our Galaxy.

Progress in many of the most exciting areas of modern astronomy relies on being able to follow up unpredictable changes or appearances of objects in the sky as rapidly as possible. It was this that led astronomers at Liverpool John Moores University (LJMU) to pioneer the development of a new generation of fully robotic telescopes, designed and built in the UK by Telescope Technologies Ltd.. Together the Liverpool Telescope (LT) and specially allocated time on the Faulkes North (FTN), soon to be joined by the Faulkes South (FTS), make up RoboNet-1.0.

Commenting on the need for a network of telescopes RoboNet Project Director, Professor Michael Bode of LJMU said “Although each telescope individually is a highly capable instrument, they are still limited by the hours of darkness, local weather conditions and the fraction of the sky each can see from its particular location on planet Earth.”

Prof. Bode added “Astronomical phenomena are however no respecters of such limitations, undergoing changes or appearances at any time, and possibly anywhere on the sky. To understand certain objects, we may even need round-the-clock coverage – something clearly impossible with a single telescope at a fixed position on the Earth’s surface.”

Thus was born the concept of “RoboNet” – a global network of automated telescopes, acting as one instrument able to search anywhere in the sky at any time and (by passing the observations of a target object from one telescope to the next in the network) being able to do so continuously for as long as is scientifically important.

The first mystery RoboNet will examine is the origin of Gamma Ray Bursts (GRBs). Discovered by US spy satellites in the late 1960’s, these unpredictable events are the most violent explosions since the Big Bang, far more energetic than supernova explosions. Yet they are extremely brief, lasting from milliseconds to a few minutes, before they fade away to an afterglow lasting a few hours or weeks. Their exact cause is still unknown, although the collapse of supermassive stars or the coalescence of exotic objects such as black holes and neutron stars are prime candidates. To study GRBs, telescopes need to be pointed at the right area of the sky extremely quickly.

In October this year, NASA will launch a new satellite named Swift, in which the UK has a major involvement, and which will pinpoint the explosions of GRBs on the sky more accurately and rapidly than ever before. The co-ordinates of each burst will be relayed to telescopes on the Earth, including those of RoboNet, within seconds of their occurrence, at the rate of one event every few days. Telescopes within the UK’s new RoboNet network are designed to respond automatically within a minute of an alert from Swift. It is in the first few minutes after the burst that observations are urgently required to enable astronomers to really understand the cause of these immense explosions, but until now such observations have been extremely difficult to secure.

RoboNet’s second major aim is to discover Earth-like planets around other stars. We now know of more than 100 extra-solar planets. However, all of these are massive planets (like Jupiter) and many are too near to their parent star, and hence too hot, to support life. RoboNet will take advantage of a phenomenon called gravitational microlensing (where light from a distant star is bent and amplified around an otherwise unseen foreground object) to detect cool planets. When a star that is being lensed in this way has a planet, it causes a short ‘blip’ in the light detected, which rapid-reacting telescopes such as the RoboNet network can follow up. In fact, the network stands the best chance of any existing facility of actually finding another Earth due to the large size of the telescopes, their excellent sites and sensitive instrumentation.

The Particle Physics and Astronomy Research Council (PPARC) have funded the establishment of RoboNet-1.0, based around using the three giant robotic telescopes at their sites across the globe. The “glue” that holds all this together is software developed by the LJMU-Exeter University “eSTAR” project, allowing the network to act intelligently in a co-ordinated manner.

Dr Iain Steele of the eSTAR project says “We have been able to use and develop new Grid technologies, which will eventually be the successor to the World Wide Web, to build a network of intelligent agents that can detect and respond to the rapidly changing universe much faster than any human. The agents act as “virtual astronomers” collecting, analysing and interpreting data 24 hours a day, 365 days a year, alerting their flesh-and-blood counterparts only when they make a discovery.”

If successful, RoboNet could be expanded to the development of a larger, dedicated global network of up to six robotic telescopes.

Professor Michael Bode of Liverpool John Moores University adds “We have led the world in the design and build of the most advanced robotic telescopes and now with RoboNet-1.0 we are set to lead the way in some of the most challenging and exciting areas of modern astrophysics”.

Original Source: PPARC News Release

What is the biggest telescope in the world?

The Nearby Supernova Factory, an international collaboration of astronomers and astrophysicists, has announced that SNIFS, the Supernova Integral Field Spectrograph, achieved “first light” during the early morning hours of Tuesday, June 8, when the new instrument acquired its first astronomical target, a Type Ia supernova designated SN 2004ca. Type Ia supernovae are the kind used by astronomers to measure the expansion of the universe.

Analysis of the initial data, plus a separate observation of the newly discovered supernova SN 2004cr on Sunday, June 20th, confirm that SNIFS ? while still in its commissioning phase ? is meeting its design goals as a remarkable new tool for observing supernovae.

SNIFS, which was recently mounted on the University of Hawaii’s 2.2-meter telescope atop Mauna Kea on the island of Hawaii, is an innovative instrument designed to track down the idiosyncrasies and precise distances of Type Ia supernovae by simultaneously obtaining over 200 spectra of each target, its home galaxy, and the nearby night sky.

SNIFS is a crucial element in the international Nearby Supernova Factory (SNfactory), initiated at the Department of Energy’s Lawrence Berkeley National Laboratory. The SNfactory’s goal is to find and study over 300 nearby Type Ia supernovae in order to reduce uncertainties about these foremost astronomical “standard candles,” whose measurement led to the discovery that the expansion rate of the universe is increasing.

“Better knowledge of these extraordinarily bright and remarkably uniform objects will make them even better tools for measuring the cosmos,” says astronomer Greg Aldering of Berkeley Lab’s Physics Division, who leads the SNfactory collaboration. “Type Ia supernovae are the key to understanding the mysterious dark energy that’s causing the universe to expand ever faster.”

The body of the SNIFS instrument was built by the SNfactory’s French collaborators, members of the Laboratoire de Physique Nucl?aire et de Haute Energies (LPNHE) in Paris, the Centre de Recherche Astronomique de Lyon (CRAL), and the Institut de Physique Nucl?aire de Lyon (INPL), supported by the Institut National de Physique Nucl?aire et de Physique des Particules (CNRS/IN2P3) and the Institut National des Sciences de l’Univers (CNRS/INSU). Berkeley Lab, with help from Yale University, developed the cameras used to detect the light from SNIFS, while the University of Chicago developed instruments to monitor the performance of SNIFS.

The SNIFS instrument produces a spectrum at each position within a six- by six-arc-second region around the target supernova, including its home galaxy and surrounding sky, by using an “integral field unit” consisting of an array of individual lenslets. Light is extracted from the telescope’s field of view by a small prism and directed to either blue-sensitive or red-sensitive, eight-megapixel, astronomical CCD cameras. Together these cameras collect all the optical light from each supernova.

A separate photometry camera, running in parallel with the spectrograph under identical observing conditions, allows spectra to be corrected for variables like thin cloud cover. A guide camera keeps the spectrograph precisely aligned on target by measuring the position of a guide star within the telescope’s wider field of view once each second, adjusting the aim if necessary.

Flown to Hilo in March and assembled in working order at sea level, SNIFS was taken apart, carried to the 4,245-meter (nearly 14,000-foot) summit of Mauna Kea, and reassembled on the University of Hawaii’s 2.2-meter telescope on April 6.

“At sea level we made sure everything was in order and also rehearsed the assembly,” says Aldering. “When you get to 14,000 feet things get tricky. Everybody carries a ‘dumb list’ so they don’t start off to do something and then forget what it was.”

Two months of engineering to align and calibrate the instrument on the telescope preceded SNIFS observation of its first new Type Ia supernova, SN 2004ca, on June 8th, in the constellation Cygnus, the swan. This was followed by the observation of SN 2004cr in the constellation Cepheus, the king, on June 20th. Shortly routine observations of SNfactory-discovered supernovae will begin.

“Now that SNIFS is in regular operation,” Aldering says, “our daily lives have changed dramatically.” After years of planning and long-distance meetings, including monthly videoconferences, “the activity level has escalated ? every day we have to react instantly as our new supernova data come pouring in.”

A full schedule ahead
The SNfactory strategy has two “pipelines,” the first being a supernova search using automated wide-field sky surveys. Data are provided by the QUEST-II 160-megapixel camera, built by Yale University and Indiana University and operated at Palomar Observatory by the QUEST-II group, as well as by the Jet Propulsion Laboratory’s Near Earth Asteroid Tracking team and the California Institute of Technology. The data are transmitted by the High-Performance Research and Education Network to the National Energy Research Scientific Computing Center (NERSC) at Berkeley Lab for identification of likely supernova candidates.

The ideal candidate is a recently exploded Type Ia supernova that is near enough for accurate measurement of its spectrum and light curve (its rising and falling brightness) but far enough away to be “in the smooth Hubble flow” ? meaning that its redshift is mostly due to the expansion of the universe alone, unaffected by the motion of its home galaxy through space.

The SNfactory’s search phase has been operating for over a year, although not at full capacity. “The search will now be going full steam,” Aldering says. “We’ll be getting a few candidates each night of the year ? more than the entire current worldwide rate of discovery.”

SNIFS is mounted on the University of Hawaii’s 2.2-meter telescope atop Mauna Kea on the island of Hawaii.

The second SNfactory pipeline passes the search candidates on to SNIFS, where the type and redshift of each supernova are determined and the most promising are selected and scheduled for more detailed study. The SNfactory uses the University of Hawaii’s telescope three times a week for half a night ? the half beginning at midnight, as a courtesy to local observers ? with SNIFS available to other projects at other times.

Eventually SNIFS will operate fully automatically. Remote control of the telescope and spectrograph was first done from Hilo, Hawaii and is now being done from Berkeley Lab and France.

SNIFS can determine a given Type Ia’s specific physical characteristics including, for example, whether or not it is unusually energetic or how much its light may have been dimmed by dust in its home galaxy. Such unparalleled spectrographic and photometric detail makes it possible to take advantage of a unique characteristic of Type Ia supernovae: that “they can be calibrated individually, not simply statistically,” Aldering says. “We’ll be able to measure the luminosity with confidence. Knowing the luminosity, we can tell you the distance with precision.”

By collecting large numbers of Type Ia supernovae in the Hubble flow, SNfactory scientists will be able to pin down the low-redshift end of the luminosity-redshift diagram upon which measures of the universe’s expansion rate are based. This, plus detailed understanding of the physical factors that cause small variations in Type Ia spectra and light curves, will improve the accuracy of the high-redshift measurements crucial to choosing among the many competing theoretical models of dark energy.

Members of the Nearby Supernova Factory team include Greg Aldering, Peter Nugent, Saul Perlmutter, Lifan Wang, Brian C. Lee, Rollin Thomas, Richard Scalzo, Michael Wood-Vasey, Stewart Loken, and James Siegrist from Berkeley Lab; Jean-Pierre Lemonnier, Arlette Pecontal, Emmanuel Pecontal, Christophe Bonnaud, Lionel Capoani, Dominique Dubet, Francois Heunault, and Blandine Lantz from CRAL; Gerard Smadja, Emmanuel Gangler, Yannick Copin, Sebastien Bongard, and Alain Castera from INPL; Reynald Pain, Pierre Antilogus, Pierre Astier, Etienne Barrelet, Gabriele Garavini, Sebastien Gilles, Luz-Angela Guevara, Didier Imbault, Claire Juramy, and Daniel Vincent from LPNHE; and Rick Kessler and Ben Dilday from the University of Chicago. Recently the astrophysics group at Yale University, under the leadership of Charles Baltay, has joined the Nearby Supernova Factory.

The Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California. Visit our website at http://www.lbl.gov.

Original Source: Berkeley Lab News Release

Image credit: Gemini
To investors looking for the next sure thing, the silver coating on the Gemini South 8-meter telescope mirror might seem like an insider’s secret tip-off to invest in this valuable metal for a huge profit. However, it turns out that this immense mirror required less than two ounces (50 grams) of silver, not nearly enough to register on the precious metals markets. The real return on Gemini’s shiny investment is the way it provides unprecedented sensitivity from the ground when studying warm objects in space.

The new coating-the first of its kind ever to line the surface of a very large astronomical mirror-is among the final steps in making Gemini the most powerful infrared telescope on our planet. “There is no question that with this coating, the Gemini South telescope will be able to explore regions of star and planet formation, black holes at the centers of galaxies and other objects that have eluded other telescopes until now,” said Charlie Telesco of the University of Florida who specializes in studying star- and planet-formation regions in the mid-infrared.

Covering the Gemini mirror with silver utilizes a process developed over several years of testing and experimentation to produce a coating that meets the stringent requirements of astronomical research. Gemini’s lead optical engineer, Maxime Boccas who oversaw the mirror-coating development said, “I guess you could say that after several years of hard work to identify and tune the best coating, we have found our silver lining!”

Most astronomical mirrors are coated with aluminum using an evaporation process, and require recoating every 12-18 months. Since the twin Gemini mirrors are optimized for viewing objects in both optical and infrared wavelengths, a different coating was specified. Planning and implementing the silver coating process for Gemini began with the design of twin 9-meter-wide coating chambers located at the observatory facilities in Chile and Hawaii. Each coating plant (originally built by the Royal Greenwich Observatory in the UK) incorporates devices called magnetrons to “sputter” a coating on the mirror. The sputtering process is necessary when applying multi-layered coatings on the Gemini mirrors in order to accurately control the thickness of the various materials deposited on the mirror’s surface. A similar coating process is commonly used for architectural glass to reduce air-conditioning costs and produce an aesthetic reflection and color to glass on buildings, but this is the first time it has been applied to a large astronomical telescope mirror.

The coating is built up in a stack of four individual layers to assure that the silver adheres to the glass base of the mirror and is protected from environmental elements and chemical reactions. As anyone with silverware knows, tarnish on silver reduces the reflection of light. The degradation of an unprotected coating on a telescope mirror would have a profound impact on its performance. Tests done at Gemini with dozens of small mirror samples over the past few years show that the silvered coating applied to the Gemini mirror should remain highly reflective and usable for at least a year between recoatings.

In addition to the large primary mirror, the telescope’s 1-meter secondary mirror and a third mirror that directs light into scientific instruments were also coated using the same protected silver coatings. The combination of these three mirror coatings as well as other design considerations are all responsible for the dramatic increase in Gemini’s sensitivity to thermal infrared radiation.

A key measure of a telescope’s performance in the infrared is its emissivity (how much heat it actually emits compared to the total amount it can theoretically emit) in the thermal or mid-infrared part of the spectrum. These emissions result in a background noise against which astronomical sources must be measured. Gemini has the lowest total thermal emissivity of any large astronomical telescope on the ground, with values under 4% prior to receiving its silver coating. With this new coating, Gemini South’s emissivity will drop to about 2%. At some wavelengths this has the same effect on sensitivity as increasing the diameter of the Gemini telescope from 8 to more than 11 meters! The result is a significant increase in the quality and amount of Gemini’s infrared data, which allows detection of objects that would otherwise be lost in the noise generated by heat radiating from the telescope. It is common among other ground-based telescopes to have emissivity values in excess of 10%

The recoating procedure was successfully performed on May 31, and the newly coated Gemini South mirror has been re-installed and calibrated in the telescope. Engineers are currently testing the systems before returning the telescope to full operations. The Gemini North mirror on Mauna Kea will undergo the same coating process before the end of this year.

Why Silver?
The reason astronomers wish to use silver as the surface on a telescope mirror lies in its ability to reflect some types of infrared radiation more effectively than aluminum. However, it is not just the amount of infrared light that is reflected but also the amount of radiation actually emitted from the mirror (its thermal emissivity) that makes silver so attractive. This is a significant issue when observing in the mid-infrared (thermal) region of the spectrum, which is essentially the study of heat from space. ?The main advantage of silver is that it reduces the total thermal emission of the telescope. This in turn increases the sensitivity of the mid-infrared instruments on the telescope and allows us to see warm objects like stellar and planetary nurseries significantly better,? said Scott Fisher a mid-infrared astronomer at Gemini.

The advantage comes at a price however. To use silver, the coating must be applied in several layers, each with a very precise and uniform thickness. To do this, devices called magnetrons are used to apply the coating. They work by surrounding an extremely pure metal plate (called the target) with a plasma cloud of gas (argon or nitrogen) that knocks atoms out from the target and deposits them uniformly on the mirror (which rotates slowly under the magnetron). Each layer is extremely thin; with the silver layer only about 0.1 microns thick or about 1/200 the thickness of a human hair. The total amount of silver deposited on the mirror is approximately equal to 50 grams.

Studying Heat Originating from Space
Some of the most intriguing objects in the universe emit radiation in the infrared part of the spectrum. Often described as “heat radiation,” infrared light is redder than the red light we see with our eyes. Sources that emit in these wavelengths are sought after by astronomers since most of their infrared radiation can pass through clouds of obscuring gas dust and reveal secrets otherwise shrouded from view. The infrared wavelength regime is split into three main regions, near- , mid- and far-infrared. Near-infrared is just beyond what the human eye can see (redder than red), mid-infrared (often called thermal infrared) represents longer wavelengths of light usually associated with heat sources in space, and far-infrared represents cooler regions.

Gemini’s silver coating will enable the most significant improvements in the thermal infrared part of the spectrum. Studies in this wavelength range include star- and planet-formation regions, with intense research that seeks to understand how our own solar system formed some five billion years ago.

Original Source: Gemini News Release

Image credit: ESA
An agreement between ESA and seven Member States to jointly build a major part of the MIRI instrument, which will considerably extend the capability of the James Webb Space Telescope (JWST), was signed, 8 June 2004.

This agreement also marks a new kind of partnership between ESA and its Member States for the funding and implementation of payload for scientific space missions.

MIRI, the Mid-Infrared Instrument, is one of the four instruments on board the JWST, the mission scheduled to follow on the heritage of Hubble in 2011. MIRI will be built in cooperation between Europe and the United States (NASA), both equally contributing to its funding. MIRI?s optics, core of the instrument, will be provided by a consortium of European institutes. According to this formal agreement, ESA will manage and co-ordinate the whole development of the European part of MIRI and act as the sole interface with NASA, which is leading the JWST project.

This marks a difference with respect to the previous ESA scientific missions. In the past the funding and the development of the scientific instruments was agreed by the participating ESA Member States on the basis of purely informal arrangements with ESA. In this case, the Member States involved in MIRI have agreed on formally guaranteeing the required level of funding on the basis of a multi-lateral international agreement, which still keeps scientists in key roles.

Over the past years, missions have become more complex and demanding, and more costly within an ever tighter budget. They also require a more and more specific expertise which is spread throughout the vast European scientific community. As a result, a new management procedure for co-ordination of payload development has become a necessity to secure the successful and timely completion of scientific space projects. ESA?s co-ordination of the MIRI European consortium represents the first time such an approach has been used, which will be applied to the future missions of the ESA long-term Science Programme ? the ?Cosmic Vision?. The technology package for LISA (LTP), an ESA/NASA mission to detect gravitational waves, is already being prepared under the same scheme.

Sergio Volonte, ESA Co-ordinator for Astrophysics and Fundamental Physics Missions, comments: ?I?m delighted for such an achievement between ESA and its Member States. With MIRI we will start an even more effective co-ordination on developing our scientific instruments, setting a new framework to further enhance their excellence.?

The James Webb Space Telescope (JWST), is a partnership between ESA, NASA and the Canadian Space Agency. Formerly known as the Next Generation Space Telescope (NGST), it is due to be launched in August 2011, and it is considered the successor of the NASA/ESA Hubble Space Telescope. It is three times larger and more powerful than its predecessor and it is expected to shed light on the ‘Dark Ages of the Universe’ by studying the very distant Universe, observing infrared light from the first stars and galaxies that ever emerged.

MIRI (Mid-Infrared Camera-Spectrograph) is essential for the study of the old and distant stellar population; regions of obscured star formation; hydrogen emission from previously unthinkable distances; the physics of protostars; and the sizes of ?Kuiper belt? objects and faint comets.

Further to the contribution to MIRI, Europe through ESA is contributing to JWST with the NIRSPEC (Near-Infrared multi-object Spectrograph) instrument (fully funded and managed by ESA) and, as agreed in principle with NASA, with the Ariane 5 launcher. The ESA financial contribution to JWST will be about 300 million Euros, including the launcher. The European institutions involved in MIRI will contribute about 70 million Euros overall.

The European institutions who signed the MIRI agreement with ESA are: the Centre Nationale des Etudes Spatiales (CNES), the Danish Space Research Institute (DSRI), the German Aerospace Centre (DLR), the Spanish Ministerio de Educaci?n y Ciencia (MEC), the Nederlandse Onderzoekschool voor Astronomie (NOVA), the UK Particle Physics and Astronomy Research Council (PPARC) and the Swedish National Space Board (SNSB).

Four European countries, Belgium, Denmark, Ireland and Switzerland contribute to MIRI through their participation into ESA?s Scientific Experiment Development programme (PRODEX). This is an optional programme, mainly used by smaller countries, by which they delegate to ESA the management of funding to develop scientific instruments.

The delivery to NASA of the MIRI instrument is due for March 2009.

Original Source: ESA News Release

Image credit: Cornell
The Arecibo Observatory telescope, the largest and most sensitive single dish radio telescope in the world, is about to get a good deal more sensitive.

Today (Wednesday, April 21) the telescope got a new “eye on the sky” that will turn the huge dish, operated by Cornell University for the National Science Foundation, into the equivalent of a seven-pixel radio camera.

The complex new addition to the Arecibo telescope was hauled 150 meters (492 feet) above the telescope’s 1,000-foot-diameter (305 meters) reflector dish starting in the early morning hours. The device, the size of a washing machine, took 30 minutes to reach a platform inside the suspended Gregorian dome, where ultimately it will be cooled and then connected to a fiber optic transmission system leading to ultra-high speed digital signal processors. The new instrument is called ALFA (for Arecibo L-Band Feed Array) and is essentially a camera for making radio pictures of the sky. ALFA will conduct large-scale sky surveys with unprecedented sensitivity, enabling astronomers to collect data about seven times faster than at present, giving the telescope an even broader appeal to astronomers.

The ALFA receiver was built by the Australian research group, Commonwealth Scientific & Industrial Research Organisation, under contract to the National Astronomy and Ionosphere Center (NAIC) at Cornell, in Ithaca, N.Y. Development of ALFA was overseen by the observatory’s technical staff. The rest of the ALFA system, including ultra-fast data processing machines, are under development at NAIC.

Radio telescopes traditionally have been limited to seeing just one spot — a single pixel — on the sky at once. Pictures of the sky have been built up by painstakingly imaging one spot after another. But ALFA lets the telescope see seven spots — seven pixels — on the sky at once, slashing the time needed to make all-sky surveys. Steve Torchinsky, ALFA project manager at Arecibo Observatory, says the new device will make it possible to find many new fast-spinning, highly dense stars called pulsars and will improve the chances of picking up very rare kinds of systems — for instance, a pulsar orbiting a black hole.

It also will map the neutral hydrogen gas in our galaxy, the Milky Way, as well as in other galaxies. Hydrogen is the most abundant element in the universe. “A whole range of science is planned for ALFA, ” says Torchinsky. “Arecibo’s large collecting area is particularly well-suited to pulsar studies.”

NAIC commissioned CSIRO to build ALFA following the success of a ground-breaking “multibeam” instrument it had designed and built for the Parkes radio telescope in eastern Australia. That instrument increased the Parkes telescope’s view 13-fold, making it practical for the first time to search the whole sky for faint and hidden galaxies.

Original Source: Cornell News Release