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Scheduled for launch in February 2005, the instruments on Astro-E2 will provide powerful tools to use the Universe as a laboratory for unraveling complex, high-energy processes and the behavior of matter under extreme conditions. These include the fate of matter as it spirals into black holes, the nature of supermassive black holes found at the center of quasars, the 100 million degree gas that is flowing into giant clusters of galaxies, and the nature of supernova explosions that create the heavier elements, which ultimately form planets.
NASA will provide the core instrument, the high resolution X- Ray Spectrometer (XRS). The XRS will be the first X-ray microcalorimeter array to be placed in orbit. It measures the heat created by individual X-ray photons.
The XRS operates at a temperature of 65 mK, which is about - -459.6 F, only 1/10 degree above absolute zero, and is held at this temperature by a three stage cooling system developed jointly by NASA's Goddard Space Flight Center, Greenbelt, MD, and the Institute of Space and Astronautical Science in Japan. The cryogenic system is capable of maintaining the temperature of the microcalorimeter array for about two years in orbit.
Japan will provide the other instruments on Astro-E2, a set of four X-ray cameras and a high-energy X-ray detector. NASA will also provide the five X-ray telescopes required to focus X- rays on the XRS and the X-ray cameras.
"This increased precision for measuring X-rays should allow fundamental breakthroughs in our understanding of essentially all types of X-ray emitting sources," said Dr. Richard Kelley, principal investigator for the U.S. participation of Astro-E2 at Goddard. "This will be especially true of matter very close to black holes and the X-ray emitting gas in clusters of galaxies."
For more additional information on the World Wide Web about Astro-E, visit:
NASA's Earth-orbiting Hubble Space Telescope took the picture on June 26, when Mars was approximately 43 million miles (68 million km) from Earth -- the closest Mars has ever been to Earth since 1988. Hubble can see details as small as 10 miles (16 km) across. The colors have been carefully balanced to give a realistic view of Mars' hues as they might appear through a telescope.
Especially striking is the large amount of seasonal dust storm activity seen in this image. One large storm system is churning high above the northern polar cap [top of image], and a smaller dust storm cloud can be seen nearby. Another large dust storm is spilling out of the giant Hellas impact basin in the Southern Hemisphere [lower right].
Hubble has observed Mars before, but never in such detail. The biennial close approaches of Mars and Earth are not all the same. Mars' orbit around the Sun is markedly elliptical; the close approaches to Earth can range from 35 million to 63 million miles.
Astronomers are interested in studying the changeable surface and weather conditions on Mars, in part, to help plan for a pair of NASA missions to land rovers on the planet's surface in 2004.
The Mars opposition of 2001 serves as a prelude for 2003 when Mars and Earth will come within 35 million miles of each other, the closest since 1924 and not to be matched until 2287.
Image Credit: NASA and the Hubble Heritage Team (STScI/AURA) Acknowledgment: J. Bell (Cornell U.), P. James (U. Toledo), M. Wolff (Space Science Institute), A. Lubenow (STScI), J. Neubert (MIT/Cornell)
NOTE TO EDITORS: For additional information, please contact Dr. James Bell, Cornell University, Department of Astronomy, 402 Space Sciences Building, Ithaca, NY 14853-6801, (phone) 607-255-5911, (fax) 607-255-5907, (email) jfb8@cornell.edu or
Dr. Philip James, Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (phone) (fax) (email) pbj@physics.utoledo.edu or
Dr. Keith Noll, Hubble Heritage Team, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, (phone) 410-338-1828, (fax) 410-338-4579, (e-mail) noll@stsci.edu.
Electronic images and additional information are available at:
http://heritage.stsci.edu and
http://oposite.stsci.edu/pubinfo/pr/2001/24 and via links in
http://oposite.stsci.edu/pubinfo/latest.html
http://oposite.stsci.edu/pubinfo/pictures.html
http://hubble.stsci.edu/go/news
The Space Telescope Science Institute (STScI) is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), for NASA, under contract with the Goddard Space Flight Center, Greenbelt, MD. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA).
Each day, NASA's Hubble Space Telescope collects enough information and images to fill five encyclopedias. Now, anyone with access to a computer and the World Wide Web can see the most exciting pictures captured by the world's first space-based optical telescope.
A new web site, "Hubble Space Telescope: New Views of the Universe," highlights the unique contributions to astronomy by this tireless observatory. The exhibition was developed by the Space Telescope Science Institute (STScI), Baltimore, MD, in collaboration with the Smithsonian Institution.
The new Internet portal seeks to simulate the experience of visiting the Smithsonian exhibition, which is now touring the country. Support for developing this exhibition was provided by NASA and the Lockheed-Martin Corporation.
Since its launch in 1990, the orbiting Hubble Space Telescope has provided unprecedented views of the Universe. Using spectacular Hubble images, the exhibition and its companion web site take visitors on a fascinating exploration of Martian weather, colliding galaxies, the tumultuous life cycles of stars, very distant celestial objects, and even a comet colliding with Jupiter.
The web site shares many of the physical exhibition's features, such as videos, a roadmap of how long the light from different objects in space takes to reach us here on Earth and virtual reality activities, which gives users a true hands-on experience of the orbiting observer.
"Hubble Space Telescope: New Views of the Universe" is a special feature of HubbleSite, Hubble's official online home and the web's most comprehensive source of Hubble news, pictures, information, and educational resources. Both web sites were developed by STScI, which manages the science program for the Hubble Space Telescope and is operated by the Association of Universities for Research in Astronomy, Inc. for NASA, under contract with NASA's Goddard Space Flight Center, Greenbelt, MD.
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency.
To experience the new "Hubble Space Telescope: New Views of the Universe," visit:
The Hubble's official online science web site is located at:
(Reported by Linda Schweizer at Carnegie Observatories to Lori Stiles, UA News Services)
Pasadena, California -- "First Light!" suddenly rang through the air in the darkened and eerily tense control room, crowded with astronomers, engineers and telescope operators.
The phenomenon known as "first light" had just been achieved for one of the twin Magellan 6.5-meter telescopes of the Carnegie Observatories.
The Magellan Project is a partnership between the Carnegie Institution of Washington, the University of Arizona, Harvard University, the Massachusetts of Technology, and the University of Michigan. These partners have been designing and constructing the unique Southern Hemisphere telescopes since 1993.
"First light" is achieved only after all of the optical elements of a telescope are placed in the mount and aligned. On September 15, two days after stormy weather, the slit of the dome atop Cerro Las Campanas was opened, and the giant 6.5-meter (22-foot diameter) mirror was uncovered and pointed towards NGC 6809, a star cluster 20,000 light years away. The stellar light streamed for the first time onto the primary mirror, then the secondary, then the tertiary, finally making its mark on the CCD (charge-coupled device) camera. Magellan Project Scientist Steve Shectman was at the controls, tweaking the focus and adjusting the thermal system, when the first image was recorded.
The small, round images of the stars indicated an extraordinarily fine optical system that could take advantage of the unusually good "seeing" at Las Campanas Observatory.
"The completion of the telescopes is a phenomenal collaborative achievement," notes Dr. Augustus Oemler, Jr., Director of Carnegie Observatories. "They will enable us to observe faint objects near the edge of the universe that are seen far back in time."
"The telescope will completely change the way we do science," commented John Mulchaey, an astronomer at Carnegie Observatories. "We can now do studies that we couldn't even dream of doing just a few years ago."
Each partner of the Magellan Project has its own scientific agenda for the new telescopes. The large apertures will facilitate observations of distant, high-redshift objects and the uniquely wide fields mean that entire clusters of galaxies can be observed at one time. Consortium astronomers hope to understand our origins by studying the chemical history of the first stars in our Galaxy, as well as the first galaxies to form near the edge of the universe. They will search for objects orbiting black holes, investigate fiery galaxy collisions, and map out the large-scale structure of the universe.
Since the time of Galileo, the need to peer deeper into the universe has driven astronomers to build ever larger and more capable telescopes. Most of these telescopes are situated in the Northern Hemisphere, but only from the Southern Hemisphere can we observe the center of our own Galaxy and our nearest neighboring galaxies, the Clouds of Magellan. The clear, dark skies of the Chilean Andes are unsurpassed anywhere on earth. The Magellan telescopes will comprise the majority of the access to the Southern sky for U.S. astronomers.
A suite of instruments, including spectrographs and cameras, will help the astronomers explore the unknown with these new giant telescopes. One of the most intriguing new instruments is aptly named MAGIC and will enable astronomers to take advantage of "targets of opportunity," such as gamma-ray bursts and supernovae, which occur suddenly and without notice. MAGIC is being built at MIT's Space Sciences Laboratory.
The Magellan mirrors are a radical departure from the conventional solid-glass mirrors used in the past. They are honeycombed on the inside, and made out of Pyrex glass that is melted, molded, and spun into shape in a specially designed rotating oven. The paraboloid mirrors were cast and polished by the University of Arizona Mirror Lab.
Matt Johns, Magellan Project Manager, and members of the Magellan team will commission the telescope over the next few months so that it will be ready for scientific observations in February 2001. The Magellan Project is named after Ferdinand Magellan, the Portuguese explorer who first circumnavigated the earth.
The 50-foot-high, 150-ton telescopes slew and point with the accuracy of a Swiss watch. In order to achieve the smooth, near-frictionless motion required for tracking astronomical objects, the telescopes float on a film of high pressure oil only two-ten-thousandths-of-an-inch thick. They are so well balanced that a tiny child pushing on the telescope could move all 150 tons.
"People don't think of Los Angeles as a location where scientific instruments of this magnitude are fabricated," according to David Chivens, one of the owners of L & F Industries, where the twin telescopes' alt-azimuth mounts were fabricated.
Science instrument commissioning will take a break in December when the dedication of the Magellan facility at Las Campanas Observatory is scheduled to take place.
The Canada-France-Hawaii Telescope has taken very detailed images that reveal that many of the stars in the Pleiades are binary. Also accessible at this site is a summary of legends about the Pleiades.
http://www.cfht.hawaii.edu/Science/Astros/Imageofweek/ciw130300.html
The U.S. Postal Service issued a set of 5 postage stamps to celebrate the 10th anniversary of the Hubble Space Telescope. They include images of the Eagle Nebula, the Ring Nebula, the Lagoon Nebula, the Egg Nebula, and the galaxy NGC 1316. They are "water-activated" rather than self-stick stamps.
Astro-E, a Japanese-U.S. X-ray mission designed to measure the energies of individual X-rays with increased precision, was apparently lost following launch from the Kagoshima Space Center in Japan at 8:30 p.m. EST Wednesday, Feb. 9, 2000.
The prime instrument on Astro-E was the X-ray Spectrometer (XRS), developed jointly by NASA's Goddard Space Flight Center, Greenbelt, Md. and Japan's Institute of Space and Astronautical Science (ISAS). The XRS measures heat created by individual X-ray photons.
Along with the XRS were four X-ray Imaging Spectrometer (XIS) instruments, a collaboration among Japanese universities and institutions and the Massachusetts Institute of Technology Center for Space Research, and the Hard X-ray Detector (HXD), built by the University of Tokyo and ISAS.
Due to a problem with the first stage of the M-5 rocket, Astro-E did not reach orbit. Astro-E was to join the recently launched European X-ray Multi-Mirror Mission (XMM) satellite and NASA's Chandra X-ray Observatory to ring in a new era of X-ray astronomy. The NASA cost for instrument development was $44.9 million.
In terms of science, the loss of Astro-E leaves a void in the understanding of higher-energy X-ray sources, such as galaxy clusters and supernova remnants and of supermassive black holes, which reveal their secrets in the iron atom emissions that Astro-E would have resolved so clearly.
Astro-E was also the test bed for the X-ray calorimeter, a key component in future X-ray missions. The X-ray calorimeter (the sensor part of XRS) is a new technology that measures the heat deposited by incoming X-ray photons. This technology has been tested on balloons. Astro-E was to be the first long-term test in the harsh environment of space.
Scientists involved in the X-Ray Multi Mirror mission - a European Space Agency (ESA) observatory with contributions from American scientists - reported today that checkout of the spacecraft's three instruments is complete and the science program can begin.
"XMM has finished its commissioning period and is now ready to be turned over to the scientists for observations," said U.S. hardware co-investigator, Dr. France Cordova from the University of California at Santa Barbara (UCSB).
Cordova and co-workers at UCSB, Los Alamos (N.M.) National Laboratory and Sandia National Laboratories in Albuquerque, N. M., contributed to the construction of one of the European instruments. Additionally they provided the data processing unit, the digital electronics modules, software and science support for the Optical Monitor instrument, a conventional but very sensitive optical and ultraviolet telescope.
"The instrument performed well during its checkout," said Cordova, "and, after 10 years of development on the ground, it's a great relief to be seeing stars." The Optical Monitor will observe the same part of the sky as the X-ray telescopes but in the ultraviolet and optical wavelengths.
Another U.S. team, led by Professor Steven Kahn from Columbia University in New York City with collaborators at the Lawrence Livermore (Calif.) National Laboratory and the University of California at Berkeley, provided two reflection grating assemblies, data analysis software and science support for the Reflection Grating Spectrometer (RGS), one of the two main X-ray instruments on the spacecraft. "The instrument checked out beautifully," said Kahn. "The resolution is even higher than we were expecting." The RGS will analyze the incoming rays and indicate in more detail the presence of Individual elements, such as oxygen and iron.
At a press conference held today in Villafranca, Spain, ESA presented the first light commissioning observations with XMM, the largest scientific telescope that the European Space Agency has launched. Included are deep X-ray images of a portion of the Large Magellanic Cloud, the nearest galaxy to our own, and a small group of more distant galaxies, as well as a high resolution X-ray spectrum of a nearby star, named HR1099. "This is the highest quality X-ray spectrum ever obtained for an astrophysical source," said Kahn. "The data show enormous detail."
ESA announced that official scientific observations with the observatory will begin in mid to late March with first results expected in March - April of this year. The Guest Observer Program, which will allow other scientists not involved with the hardware teams to make observations with the spacecraft, will begin in June. As a result of a competitive selection process, U.S. scientists will receive about one fifth of the observing time during its first two years in orbit.
XMM is an X-ray satellite designed to provide high quality X-ray spectra of X-ray sources from black holes to very hot objects in the universe. Scientists expect XMM will address a number of cosmic mysteries, ranging from the nature of black holes to the origin of the universe. XMM will investigate faint, faraway galaxies, supernova remnants, accreting neutron stars, magnetically active flare stars and more.
NASA's involvement in the mission includes the contribution of critical components for two of the spacecraft's three science instruments and participation in the science-observing program. Mission scientists Prof. Richard Griffiths from Carnegie Mellon University in Pittsburgh, and Goddard scientist, Dr. Richard Mushotzky provided science oversight and advice to the ESA project. Mushotzky is also the U.S. project scientist for XMM.
XMM was launched Dec. 10 1999 from French Guyana on an Ariane 5 launch vehicle.
===================================================================
Cambridge, MA--NASA's Chandra X-ray Observatory opened a new era in astronomy Saturday, August 28, by making the most precise measurements ever recorded of the energy output from the 10 million degree corona of a star. Last weekend's observations came after the successful activation of an instrument developed by MIT that will allow a one-thousand-fold improvement in the capability to measure X-ray spectra from space.
The new measurements, made with the High Energy Transmission Grating Spectrometer, join spectacular images taken last week by Chandra of the aftermath of a gigantic stellar explosion. The spectrometer is one of four key instruments aboard Chandra, and the second to be activated. The others will be turned on over the next two weeks.
The spectrometer activated yesterday spreads the X-rays from Chandra's mirrors into a spectrum, much as a prism spreads light into its colors. The spectrum then can be read by Chandra's imaging detectors like a kind of cosmic bar code from which scientists can deduce the chemical composition and temperature of the corona. A corona is a region of hot gas and magnetic loops that extend hundreds of thousands of miles above the star's visible surface and is best studied with X-rays.
"The success of the new spectrometer is definitely a major milestone for modern astronomy," said MIT Professor Claude R. Canizares, principal investigator for the instrument and associate director of the Chandra X-ray Observatory Center (CXC). "Within the first hour we had obtained the best X-ray spectrum ever recorded for a celestial source. We can already see unexpected features that will teach us new things about stars and about matter at high temperatures."
The spectrometer measured X-rays from the star Capella, which is 40 light years away in the constellation Auriga. Capella is actually two stars orbiting one another and possibly interacting in ways that pump extra heat into the corona, which appears more active than that of the sun. How a star manages to heat its corona to temperatures a thousand times higher than its own surface is still a puzzle, which astronomers hope can be solved by observations like this one. Other prime targets for Chandra's spectrometers over the next few months include black holes, quasars and supernova explosions.
The grating spectrometer consists of hundreds of gold gratings, each about the size of a postage stamp. The surface of each grating resembles a precise picket fence, with microscopic gold pickets 500 times thinner than a human hair. These are spaced every 2000 angstroms, or less than half the wavelength of visible light. The instrument was developed at MIT's Center for Space Research, which Professor Canizares directs, by adapting techniques usually used to make computer chips. Some of these adaptations have found their way back as improvements in the chip-making industry.
The grating spectrometer is one of two such devices carried by Chandra. The other, a low-energy grating built by a Dutch-German team, will be activated next week. Chandra also contains two detectors. One, built by researchers at Pennsylvania State University and MIT, was turned on two weeks ago and has recorded all the images and spectra seen so far. The second, built by the Smithsonian Astrophysical Observatory, is being activated this week.
Dr. Stephen Murray of the Harvard-Smithsonian Center for Astrophysics summarized the expected impact of Chandra's high resolution X-ray spectroscopy with these words: "A picture is worth a thousand words, a spectrum is worth a million."Capella's spectrum and further information about Chandra's High Energy Transmission Grating Spectrometer may be found at: http://space.mit.edu/CSR/hetg_info.html
The Chandra X-ray Observatory Center was named in honor of the late Nobel laureate Subrahmanyan Chandrasekhar. NASA's Marshall Space Flight Center manages the Chandra program. TRW, Inc., Redondo Beach, CA, is the prime contractor for the spacecraft. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science and flight operations from Cambridge, MA. The first Chandra images and more information on the Chandra X-ray Observatory Center are available at: http://chandra.harvard.edu and http://chandra.nasa.gov
Extraordinary first images from NASA's Chandra X-ray Observatory trace the aftermath of a gigantic stellar explosion in such stunning detail that scientists can see evidence of what may be a neutron star or black hole near the center. Another image shows a powerful X-ray jet blasting 200,000 light years into intergalactic space from a distant quasar.
Released today, both images confirm that NASA's newest Great Observatory is in excellent health and its instruments and optics are performing up to expectations. Chandra, the world's largest and most sensitive X-ray telescope, is still in its orbital check-out and calibration phase.
"When I saw the first image, I knew that the dream had been realized," said Dr. Martin Weisskopf, Chandra Project Scientist, NASA's Marshall Space Flight Center, Huntsville, AL. "This observatory is ready to take its place in the history of spectacular scientific achievements."
"We were astounded by these images," said Harvey Tananbaum, Director of the Smithsonian Astrophysical Observatory's Chandra X- ray Center, Cambridge, MA. "We see the collision of the debris from the exploded star with the matter around it, we see shock waves rushing into interstellar space at millions of miles per hour, and, as a real bonus, we see for the first time a tantalizing bright point near the center of the remnant that could possibly be a collapsed star associated with the outburst."
After the telescope's sunshade door was opened last week, one of the first images taken was of the 320-year-old supernova remnant Cassiopeia A, which astronomers believe was produced by the explosion of a massive star. Material blasted into space from the explosion crashed into surrounding material at 10 million miles per hour. This collision caused violent shock waves, like massive sonic booms, creating a vast 50-million degree bubble of X-ray emitting gas.
Heavy elements in the hot gas produce X-rays of specific energies. Chandra's ability to precisely measure these X-rays tells how much of each element is present. With this information, astronomers can investigate how the elements necessary for life are created and spread throughout the galaxy by exploding stars.
"Chandra will help to confirm one of the most fascinating theories of modern science -- that we came from the stars," said Professor Robert Kirshner of Harvard University. "Its ability to make X-ray images of comparable quality to optical images will have an impact on virtually every area of astronomy."
Chandra also imaged a distant and very luminous quasar -- a single star-like object -- sporting a powerful X-ray jet blasting into space. The quasar radiates with the power of 10 trillion suns, energy which scientists believe comes from a supermassive black hole at its center. Chandra's image, combined with radio telescope observations, should provide insight into the process by which supermassive black holes can produce such cosmic jets.
"Chandra has allowed NASA to seize the opportunity to put the U.S. back in the lead of observational X-ray astronomy," said Dr. Edward Weiler, Associate Administrator of Space Science, NASA Headquarters, Washington, DC. "History teaches us that whenever you develop a telescope 10 times better than what came before, you will revolutionize astronomy. Chandra is poised to do just that."
The Chandra X-ray observatory was named in honor of the late Nobel laureate Subrahmanyan Chandrasekhar. NASA's Marshall Space Flight Center manages the Chandra program. TRW, Inc., Redondo Beach, CA, is the prime contractor for the spacecraft. The Smithsonian's Chandra X-ray Center controls science and flight operations from Cambridge, MA.
See:
http://chandra.nasa.gov and http://chandra.harvard.edu
NASA Science News for July 23, 1999:
Why launch Chandra late at night? Blame Newton and Kepler: Chandra's beautiful early morning launch will place it into an orbit unlike that of NASA's other Great Observatories. To find out why, see the FULL STORY at URL http://science.nasa.gov/newhome/headlines/ast23jul99_1.htm
Also see: Chandra X-ray Observatory Center Website
NASA will launch a Space Shuttle mission to the Hubble Space Telescope in October so astronauts can replace portions of the spacecraft's pointing system, which has begun to fail. Hubble is operating normally and continuing to conduct its scientific observations, but only three of its six gyroscopes -- which allow the telescope to point at stars, planets and other targets -- are working properly. Two have failed and another is acting abnormally. If fewer than three gyroscopes are operating, Hubble cannot continue its science mission and automatically places itself in a protective "safe mode."
"The Hubble Space Telescope is the crown jewel of NASA's space observatories, and we need to do everything within reason to maintain the scientific output of this national treasure," said Dr. Edward Weiler, Associate Administrator for the Office of Space Science, NASA Headquarters, Washington, DC. "We appreciate the rapid response of the Space Shuttle community to this request."
"When Hubble reached the point of having no back-up gyros, our flight rules said we must look at what we term a 'call-up mission' to correct the situation," said Dr. John H. Campbell, the telescope's Project Director at NASA's Goddard Space Flight Center, Greenbelt, MD. "Since we are already involved in preparations for the scheduled third servicing mission next year, we essentially decided to divide the planned mission into two flights and reduce the workload on each." In addition to replacing all six gyroscopes on the October flight, the crew will replace a guidance sensor and the spacecraft's computer. The new computer will reduce the burden of flight software maintenance and significantly lower costs. A voltage/temperature kit will be installed to protect spacecraft batteries from overcharging and overheating when the spacecraft goes into safe mode. A new transmitter will replace a failed spare currently aboard the spacecraft, and a spare solid state recorder will be installed to allow efficient handling of high- volume data. Both missions will replace telescope insulation that has degraded. The insulation is necessary to control the internal temperature on the Hubble.
The later servicing mission will focus on installing the Advanced Camera for Surveys. With its new imaging capabilities, this camera will be 10 times more powerful than the present Faint Object Camera. New efficient rigid solar arrays will replace the existing solar arrays. Astronauts also will install the Aft- Shroud Cooling System. This new system is designed to carry heat away from the scientific instruments and to allow the instruments to operate better at lower temperatures. The cooling system allows multiple instruments to operate simultaneously, helping the science team maintain the program's high productivity.
In addition, an advanced cooling system will be installed on the Near-Infrared Camera and Multiobject Spectrometer, which became dormant after its solid nitrogen coolant was exhausted in January 1999.
Ground controllers are slowly gaining control of NASA's Wide-Field Infrared Explorer (WIRE), but the entire supply of frozen hydrogen needed to cool its primary scientific instrument has been released into space, ending the scientific mission of the spacecraft.
"We are very disappointed at the loss of WIRE's science program," said Dr. Ed Weiler, NASA's Associate Administrator for Space Science at NASA Headquarters, Washington, DC. "We are establishing a formal anomaly investigation board to find out what happened, which will help us to plan future missions. I'm confident that many of the scientific goals can be accomplished by upcoming missions such as the Space Infrared Telescope Facility, so it will be science delayed rather than science lost."
Spacecraft controllers believe the primary telescope cover was released about three days earlier than planned. As a result sunlight began to fall on the instrument's cryostat, a container of frozen hydrogen designed to cool the instrument. The hydrogen then warmed up and vented into space at a much higher rate than it was designed to do, causing the spacecraft to spin. Controllers do not know what specifically caused the cover to be released.
WIRE's primary instrument is a 30-centimeter aperture (12.5-inch) Cassegrain telescope enclosed inside a solid hydrogen cryostat. The cryostat was designed to cool the telescope's inner workings to minus-430 degrees F -- cold enough so that the telescope's own heat emissions would not mask the infrared light that it is trying to detect in space.
By early Saturday, the spacecraft's rate of spin had stabilized at about 60 revolutions per minute, giving controllers hope they could start the painstaking process of regaining control of the 563-pound spacecraft. On Saturday, ground controllers developed and uploaded a new computer program to WIRE that began imparting small, countering forces using the satellite's onboard magnetic attitude control system to gently slow the spacecraft's spin.
Controllers have been successfully using this approach to slowly regain control of the spacecraft and reduce the spin rate approximately 3 degrees per second per orbit. WIRE is now rotating about 250 degrees per second. The objective is to reduce the spin rate sufficiently that the onboard system will take over and provide full attitude control. Controllers are hopeful this will be accomplished by the end of this week. "The spacecraft was never designed to be controlled in this manner," said Jim Watzin, Small Explorer Project Manager, "so it's slow, tedious work. I'm confident by week's end we will have WIRE in a stable configuration, available for any analysis deemed appropriate."
WIRE was launched March 4 at 9:57 p.m. EST from Vandenberg Air Force Base, CA. When the spacecraft made its second pass over one of the WIRE tracking stations, ground controllers determined that WIRE was spinning instead of maintaining a stable position in orbit, and temperatures for the cryostat and the instrument were warmer than expected.
After the anomaly investigation board completes its work with WIRE, engineers plan to use the spacecraft as an engineering testbed to evaluate advanced attitude control systems, communications, and data handling and operations.
It had long been ESO's intention to provide "real" names to the four VLT Unit Telescopes, to replace the current, somewhat dry and technical designations as UT1 to UT4. Four pregnant names of objects in the sky in the Mapuche language were chosen. This indigeneous people lives mostly in the area south of Santiago de Chile.
A essay contest was arranged in this connection among schoolchildren of the Chilean II Region of which Antofagasta is the capital to write about the implications of these names. It drew many excellent entries dealing with the rich cultural heritage of ESO's host country.
The jury was unanimous in its choice of the winning essay. This was submitted by 17-year old Dora Tejada C. from Chiquicamata near the city of Calama. She received the prize, an amateur telescope, during the Paranal Inauguration.
Henceforth, the four Unit Telescopes will be known as ANTU (UT1; pronounced an-too; The Sun), KUEYEN (UT2; kew-yen; The Moon), MELIPAL (UT3; me-li-pal; The Southern Cross) and YEPUN (UT4; ye-poon; Sirius), respectively. An audio sequence with these names pronounced by a native speaker will become available on the ESO web.
The Wide Field Infrared Explorer (WIRE) was launched on March 4, 1999 after a delay on March 1. WIRE's telescope is a 30- centimeter (12.5-inch) aperture Cassegrain instrument enclosed in a two-stage, solid-hydrogen thermos-like cryostat, which will keep the instrument's mirrors cooled to below -260 Celsius (-436 F). The telescope must be cold so that its own heat emission doesn't overwhelm the light that it is trying to detect from space.
The four-month mission will help answer questions about how and when galaxies formed, and the subsequent history of star- formation in the universe. The WIRE spacecraft will be inserted into an orbit with an altitude of 540 kilometers (340 miles) above the Earth, and will orbit every 90 minutes. The mission is managed by NASA's Goddard Space Flight Center, Greenbelt, MD, and the WIRE science operations center is located at the Infrared Processing and Analysis Center (IPAC), California Institute of Technology, Pasadena, CA.
For more information about the Wide-Field Infrared Explorer,
check the web pages at the following URLs:
Wire Project: http://sunland.gsfc.nasa.gov/smex/wire/
Wire Science: http://www.ipac.caltech.edu/wire/
SWAS Project: http://sunland.gsfc.nasa.gov/smex/swas/
SWAS Science:
http://cfa-www.harvard.edu/cfa/oir/Research/swas.html
An ailing gyroscope on NASA's Hubble Space Telescope that engineers had anticipated would fail since it first started behaving erratically in January 1999, stopped functioning today, April 21, 1999. The powerful telescope continues to operate normally on its three good gyroscopes.
Gyroscope 3 is inoperable. Gyroscopes 1, 2 and 5 are the three working gyroscopes remaining aboard Hubble and are functioning normally. The ailing gyroscope has not been used for pointing purposes since it began acting erratically. Because it was not active in the guiding loop, there is no impact to the science program.
Hubble requires three of its normal complement of six gyros to point accurately the telescope for science observations. The failure of gyroscope 3 means there are no available spares. Any further gyroscope failure will cause the observatory to go into a protective safe mode that gives ground controllers complete control of the telescope, but prevents its use for taking observations of the sky.
Hubble will be visited by a Space Shuttle crew in October during Servicing Mission 3A. Astronauts will replace all the gyroscopes, a fine guidance sensor, a transmitter, a spare solid state recorder and a high voltage/temperature kit for protecting batteries from overheating. Plus, the crew will install an advanced computer.
Servicing Mission 3B, to be conducted in year 2000, will install a new scientific instrument, the Advanced Camera for Surveys, as well as new solar arrays and a new cooling system. Both missions will patch over telescope skin that has degraded over the years.
The Hubble's failing gyros may be forcing an early astronaut visit, late in 1999. Dan Goldin, NASA Administrator, spoke to Congress about the possibility in late February. See http://cnn.com/TECH/space/9902/24/hubble.trouble.reut/
In December 1998, NICMOS on Hubble ran out of coolant, so is not operating any more. It is hoped that an electronic cooler will revive this instrument when it is brought to HST by a space shuttle at the serving mission tentatively scheduled for April 2000. At the same time, an Advanced Camera for Surveys will be put on HST, with a wider field of view and smaller pixels than WFPC2. WFPC2 will remain; the Faint Object Camera will be replaced.
NASA's Advanced X-ray Astrophysics Facility has been renamed the Chandra X-ray Observatory in honor of the late Indian-American Nobel laureate, Subrahmanyan Chandrasekhar. The telescope is scheduled to be launched no earlier than April 8, 1999 aboard the Space Shuttle Columbia mission STS-93, commanded by astronaut Eileen Collins.
Chandrasekhar, known to the world as Chandra, which means "moon" or "luminous" in Sanskrit, was a popular entry in a recent NASA contest to name the spacecraft. The contest drew more than six thousand entries from fifty states and sixty-one countries. The co-winners were a tenth grade student in Laclede, Idaho, and a high school teacher in Camarillo, CA.
The Chandra X-ray Observatory Center (CXC), operated by the Smithsonian Astrophysical Observatory, will control science and flight operations of the Chandra X-ray Observatory for NASA from Cambridge, Mass.
"Chandra is a highly appropriate name," said Harvey Tananbaum, Director of the CXC. "Throughout his life Chandra worked tirelessly and with great precision to further our understanding of the universe. These same qualities characterize the many individuals who have devoted much of their careers to building this premier x-ray observatory."
"Chandra probably thought longer and deeper about our universe than anyone since Einstein," said Martin Rees, Great Britain's Astronomer Royal.
"Chandrasekhar made fundamental contributions to the theory of black holes and other phenomena that the Chandra X-ray Observatory will study. His life and work exemplify the excellence that we can hope to achieve with this great observatory," said NASA Administrator Dan Goldin.
Widely regarded as one of the foremost astrophysicists of the 20th century, Chandrasekhar won the Nobel Prize in 1983 for his theoretical studies of physical processes important to the structure and evolution of stars. He and his wife immigrated from India to the U.S. in 1935. Chandrasekhar served on the faculty of the University of Chicago until his death in 1995.
The Chandra X-ray Observatory will help astronomers worldwide better understand the structure and evolution of the universe by studying powerful sources of X rays such as exploding stars, matter falling into black holes and other exotic celestial objects. X-radiation is an invisible form of light produced by multimillion degree gas. Chandra will provide x-ray images that are fifty times more detailed than previous missions. At more than 45 feet in length and weighing more than five tons, it will be one of the largest objects ever placed in Earth orbit by the Space Shuttle.
Tyrel Johnson, a student at Priest River Lamanna High School in Priest River, Idaho, and Jatila van der Veen, a physics and astronomy teacher at Adolfo Camarillo High School in Camarillo, California, who submitted the winning name and essays, will receive a trip to the Kennedy Space Center in Florida to view the launch of the Chandra X-ray Observatory, a prize donated by TRW.
NASA's newest orbiting telescope, which will study X-rays produced by some of the most violent events in the universe, will carry the name of pioneering University of Chicago astrophysicist Subrahmanyan Chandrasekhar, NASA announced.
A native of India, Chandrasekhar was called Chandra by his friends and colleagues. He died in 1995 at the age of 84 after making major discoveries in astrophysics that spanned more than 60 years. All three of NASA's Great Observatories, including the Hubble Space Telescope and the Compton Gamma Ray Observatory, are named for University of Chicago scientists.
Chandrasekhar received the Nobel Prize in physics in 1983 for his studies on the physical processes important to the structure and evolution of stars. By applying the laws of physics to the universe, Chandrasekhar launched the field of astrophysics, said Michael Turner, Bruce and Diana Rauner Distinguished Service Professor and Chairman of the Department of Astronomy & Astrophysics at the University of Chicago.
"Following in Chandra's path, astrophysicists today use the laws of physics to help understand how the universe began and might end, how stars are born, evolve and die, and the nature of the most interesting objects in the cosmos, including black holes and neutron stars," Turner said. Chandrasekhar's work on the mass limit of white dwarfs set the stage for understanding violent events in the evolution of stars, according to Peter Vandervoort, Professor in Astronomy & Astrophysics at Chicago. "His work lays the foundation for the modern understanding of neutron stars and black holes that will come from the data collected by the Chandra Observatory."
Chandrasekhar's contributions extend over an amazingly broad spectrum of astrophysical research, Vandervoort added. "He had an extraordinary intellect and the rarest kind of scientific integrity. He was a person apart in many respects. We were all in awe of him."
NASA plans to launch the Chandra Observatory no earlier than April 8, 1999 on the Space Shuttle Columbia. The Chandra Observatory, the most powerful X-ray observatory ever built, measures 45 feet long, weighs 5 tons, and costs $1.3 billion. Scientists will use the observatory to examine X-rays emanating from incredibly dense, collapsed objects such as white dwarfs, neutron stars and matter falling into black holes.
"Chandrasekhar's work opened the door to the existence of collapsed objects, either neutron stars with diameters of about 10 miles, or black holes with no physical surface but with characteristic dimensions of less than a mile," said Eugene Parker, the S. Chandrasekhar Distinguished Service Professor Emeritus. At age 19 in 1930, Chandrasekhar worked out that a star whose nuclear fuel is exhausted will remain a star in the form of a slowly cooling white dwarf about the size of Earth, only if the star's mass is less than 1.4 times the mass of the sun.
"If the mass of the star is greater than 1.4 solar masses, now called the Chandraskhar limit, then the burned out star cannot avoid falling in upon itself, vanishing from the realm of ordinary stars," Parker explained. "There are many stars with masses far in excess of 1.4 solar masses, burning out in only a few million years because of their great luminosity. So there must be many stars that have suffered this fate."
NASA sponsored a naming contest for the observatory that attracted more than 6,000 entries. An independent panel selected two winners, who both wrote essays suggesting Chandra's name: Mrs. Jatila van der Veen, a physics and astronomy teacher at Adolfo Camarillo High School in Camarillo, Calif., and Tyrel Johnson, a student at Priest River Lamanna High School in Laclede, Idaho.
"That Chandra's name might be nominated by a panel of elite scientists would not be surprising. But that it was put into nomination from the public, strongly so, is really quite surprising," said Robert M. Wald, Professor in Physics. "Chandra himself did not promote his work or do anything to create a public relations image for it."
Chandrasekhar was more than just one of the century's leading astrophysicists. His commitment to teaching was legendary. In the 1940s, he drove 200 miles round trip each week from Yerkes Observatory in Williams Bay, Wis., to the University to teach a class on stellar atmospheres. One day he insisted on driving from Yerkes to teach the class despite a heavy snowstorm. He ended up teaching a class of only two that day.
The two students -Tsung Dao Lee and Chen Ning Yang-won the Nobel Prize in physics in 1957, obtaining the distinction even before their professor.
"It was important to Chandra to be a teacher and ultimately a role model," Vandervoort said. "He often said that as he got older, his colleagues did not, because he always seemed to be working with people at the beginning of their careers. He often joked that as a general rule he got along better with the children of his colleagues than with the colleagues themselves."
Chandrasekhar was born in Lahore, India, on Oct. 19, 1910. He received his B.A. from Madras University, India, in 1930 and his doctorate from Trinity College, Cambridge University, in 1933. He joined the University of Chicago faculty as a research associate in 1937. Chandrasekhar received the Morton D. Hull Distinguished Service Professorship in 1952.
Chandrasekhar developed his own astonishing style of research that entailed tackling first one field of astrophysics and then another in great depth. He wrote more than half a dozen definitive books describing the results of his investigations on topics ranging from radiative transfer of energy through the atmospheres of stars to the motions of stars within galaxies, and from magnetohyrodynamics to Einstein's theory of general relativity and black holes.
Two of Chandra's colleagues in the Department of Astronomy & Astrophysics, Don Q. Lamb and Robert Rosner, will be among the scientists who will conduct research with the Chandra Observatory. They and University research scientists Peter Freeman and Cole Miller also helped design and test the telescope's data analysis software.
Also involved was Vinay Kashyap, who received his doctorate in astronomy from the University. Kashyap now works at the Harvard-Smithonian Center for Astrophysics, where he serves as a member of the Chandra Observatory science team.
Lamb will use the Chandra Observatory to study the production of X-rays by compact stars, which is related both to Chandrasekhar's earliest work and to some of his later work in general relativity and the mathematical properties of black holes. The telescope's launch comes at an opportune time, Lamb said, because the study of X-ray bursts and other burstlike phenomena now is undergoing a period of great intellectual ferment.
"The Chandra Observatory has wonderful capabilities for advancing our understanding of these incredibly energetic and violent phenomena," he said.
Rosner will use the Chandra Observatory to study X-ray emissions from stars to better understand the sun's X-ray emissions. The research may help answer questions about the sun's interaction with the Earth's atmosphere during their youth and the possible biological effects of high levels of ionizing radiation during this epoch.
NASA's infrared telescope, which is still under construction, is the only Great Observatory that remains unnamed. Together these orbiting observatories will collect data from across most of the electromagnetic spectrum with multiple instruments over a period of years.
The Hubble Space Telescope, launched in 1990, is named for Edwin Powell Hubble, who earned his bachelor's degree at the University in 1910 and his doctorate in 1917. Hubble showed that galaxies besides our own existed in the universe, and that the universe is expanding. These findings form the cornerstone of the Big Bang theory of the universe's origin and opened the field of cosmology.
In 1991 the Compton Gamma Ray Observatory was named for Arthur Holly Compton, who served on the University of Chicago faculty from 1923 to 1945. Compton earned the 1927 Nobel Prize in physics for his scattering experiment, which demonstrated that light has characteristics of both a wave and a particle.
Compton also made major contributions to the understanding of cosmic rays, particles that travel through space at velocities near the speed of light. During World War II, he directed the Metallurgical Laboratory at Chicago where Enrico Fermi and colleagues produced the first controlled nuclear chain reaction.
Nearly 50 "VLT Astronomical Images" are now available. To provide an overview and to facilitate access, an index has been established and subpages have been set up by object category.
The index may be reached at:
http://www.eso.org/outreach/info-events/ut1fl/astroimages.html
The 3rd HST servicing mission (STS-103 Columbia) was on the Space Shuttle manifest for Nov. 1999, but it looks like it will be put off until the spring of 2000 because of the delay in launching AXAF and all the International Space Station activity.
During the servicing mission, the Advanced Camera, NICMOS Cryocooler and two new solar panels will be installed, the telescope will be reboosted into a higher orbit, some of the gyros will be replaced, and thermal patches will be placed on the body of the telescope.
Also, a new 486 spacecraft computer will replace the current DF224 and a spare Solid State Recorder will be installed.
Slides and viewgraphs of the Very Large Telescope Array are available at http://www.eso.org/outreach/epr/slides/set-02/index.html
The Rossi X-Ray Timing Explorer, named for the American space scientist Bruno B. Rossi, is optimized for studying the temporal and spectral variations of bright sources of X-rays on time-scales from years to microseconds (p. 76). This has enabled it to study the turbulent regions near the surfaces of neutron stars and black holes in binary systems, where the emission has been found to flicker at rates up to 1200 times a second. It also monitors the sky for the appearance of new sources as well as studying the long term behavior of known sources.
A summary paper is available .
Incorrect
A Cassegrain telescope has a hole in its secondary mirror.
Correct
A Cassegrain telescope has a hole in its primary mirror; the secondary mirror
reflects light through that hole, where it eventually hits an eyepiece, film,
a CCD, or other detector.
Subaru is the Japanese word for "Pleiades," and has been given to their giant telescope being completed on Mauna Kea, next to the Keck Telescope. Here is a press release:
At the beginning of this month, SUBARU Telescope with the world's largest monolithic optical-infrared primary mirror, passed several important milestones on its way to "first- light" planned for January of 1999. On November 5th, 1998, the telescope's 8.3-meter primary mirror arrived without incident at the summit of Mauna Kea, Hawaii and was formally accepted on the following day by the Director of SUBARU Telescope, Norio Kaifu. Just three days later, on November 8th, 1998, the primary mirror was successfully aluminized for the first time.
We will be providing regular updates at this Website to keep you informed about our progress during this very busy period in our history. This is also where we will be posting results from our "first-light" observations at the end of January.
The European Southern Observatory's Very Large Telescope (VLT)'s first 8.2-m component had first light, and is providing excellent images. The VLT, which will ultimately contain 4 8.2-m telescopes plus three smaller telescopes, is on Cerro Paranal in the Atacama Desert of Chile. The other 8.2-m telescopes are to see first light in March 1999, March 2000, and March 2001, respectively. Ultimately, all the telescopes should be usable together as an interferometer. Each of the 8.2-m mirrors is very thin, only 4-inches from front to back, and is kept in place by pistons in the back. The piston positions are controlled as "active optics" to maintain the mirror shape. Ultimately, "adaptive optics," with feedback 100 times each second, will be installed to compensate for the turbulence that causes seeing and thus to provide images sharper by a factor of perhaps 10.
Following the very successful First Light Event in late May, the first 8.2-m Unit Telescope (UT1) of the ESO Very Large Telescope (VLT) has continued to demonstrate its great potential. These developments are reported on a dedicated webpage with new VLT Information (URL: http://www.eso.org/outreach/info-events/ut1fl).
The VLT and Paranal - a fine combination
The advanced, computerized system that provides total optical control of the telescope has been further optimized and is now operated in a fully active optics closed-loop mode. This implies that the telescope functions automatically (much like a giant autofocus camera). During recent test observations, it continuously corrects the shape of the primary mirror and the positioning of the secondary mirror. The latter, a light-weight Beryllium mirror, is now providing so-called field stabilization at a rate of 10 times per second (10 Hz). This innovative system decisively improves the achievable image quality.
The site of the VLT Observatory, Cerro Paranal, was chosen after more than 8 years of careful testing by ESO, between 1983 and 1991. The meteorological conditions at this isolated spot in the Chilean Atacama desert were found to be among the best on the Earth for astronomical observations. This has been amply confirmed, both in terms of low atmospheric turbulence and high visibility in the infrared spectral region, because of the very low water content in the air over this extremely dry site.
The sharpest images yet
The stable atmosphere above Paranal, in combination with optimized, total control of the VLT UT1 optics, has now allowed some of the sharpest astronomical images to be obtained. In fact, during a period of particularly good conditions, images were recently taken with a quality even better than the excellent ones available at the moment of "First Light".
The present photo is a reproduction of a digital image that was obtained in the early morning of June 6, 1998. It shows the central part of the southern globular cluster Messier 55 (or NGC 6809) in the constellation Sagittarius. The exposure lasted 30 seconds and was made with the VLT Test Camera through an optical filtre isolating mostly red light (570 - 700 nm). It is here shown exactly as it was obtained ("raw image"), without any image processing. The brightness level in the reproduction has been set so that the fainter stars are well visible. The field shown is 83 x 83 arcsec; each pixel measures 0.0455 arcsec.
Images of a large number of stars over the entire field have been measured and consistently show a stunning image quality. The full-width-at-half-maximum (FWHM) is only 0.27 arcsec! Moreover, the images are very nearly round - the measured image elongation is negligible at the 5% level (0.015 arcsec).
This capability used on earth would allow us to clearly see the two headlights of a car at a distance of no less than 1200 kilometres (the distance from Paranal to Santiago de Chile) - an astonishing performance of a ground-based telescope. It confirms that the VLT will be able to take full advantage of moments of particularly good observing conditions at Paranal and may soon begin to look beyond current horizons.
Present work
The UT1 has now entered the "Commissioning Phase" during which all systems are thoroughly tested and further tuned, leading up to "Science Verification" observations in the second half of August 1998. Thereafter, the two main astronomical instruments, FORS and ISAAC, will be mounted at the telescope and thoroughly tested. The UT1 will receive the first "visiting astronomers" for regular observing runs from April 1, 1999. Further images of astronomical objects from the VLT UT1 will be published at irregular intervals.
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This is the caption to ESO PR Photo 15/98 [JPG, 304k]. It is also available in a high-resolution version [JPEG, 1.2Mb]. It may be reproduced, if credit is given to the European Southern Observatory.
ESO Press Information is made available on the World-Wide Web (URL: http://www.eso.org/outreach/press-rel/).
The first of the 8.2-m telescopes of the Very Large Telescope in Chile, a project of the European Southern Observatory, saw its first light in May 1998.
The European Southern Observatory announces that First Light has been achieved with the first VLT 8.2-m Unit Telescope at the Paranal Observatory. Scientifically useful images have been obtained as scheduled, on May 25 - 26, 1998.
A first analysis of these images convincingly demonstrates the exceptional potential of the ESO Very Large Telescope. Just one month after the installation and provisional adjustment of the optics, the performance of this giant telescope meets or surpasses the design goals, in particular as concerns the achievable image quality. Exposures lasting up to 10 minutes confirm that the tracking, crucial for following the diurnal rotation of the sky, is very accurate and stable.
It appears that the concept developed by ESO for the construction of the VLT, namely an actively controlled, single thin mirror, yields a very superior performance.
In fact, the angular resolution achieved even at this early stage is unequalled by any large ground-based telescope.
The combination of large area and fine angular resolution will ultimately result in a sensitivity for point sources (e.g. stars), which is superior to any yet achieved by existing telescopes on Earth.
The present series of images demonstrate these qualities and include some impressive first views with Europe's new giant telescope. After further optimization of the optical, mechanical and electronic systems, and with increasing operational streamlining, this telescope will be able to deliver unique astronomical data of the highest quality. The commissioning and science verification phases of the complex facility including instruments will last until April 1, 1999, at which time the first visiting astronomers will be received.
The full significance of this achievement for astronomy will take time to assess.
For Europe, this is a triumph of the collaboration between nations, institutions and industries. For the first time in almost a century, European astronomers will have at their disposal the best optical/infrared telescope in the world.
We can now look forward with great expectations to the realization of many exciting research projects.
The First Light Images
Images of various celestial objects were obtained with the VLT CCD Test Camera, some of which are included in a new series, First Astronomical Images from the VLT UT1.
None have been subjected to image processing beyond flat-fielding (to remove variations of the digital detector sensitivity over the field) and cosmetic cleaning. They all display the recorded image structure, pixel by pixel. A detailed evaluation with accompanying explanations is presented in the figure captions.
1. Omega Centauri Tracking Tests
This 10-minute image demonstrates that the telescope is able to track continuously with a very high precision and thus is able to take full advantage of the frequent, very good atmospheric conditions at Paranal. The images of the stars in this southern globular cluster are very sharp (0.43 arcsec) and are perfectly round, everywhere in the field.
2. The Quadruple Clover Leaf Quasar
This 2-minute exposure of the well-known Clover Leaf quasar, a quadruple gravitational lens in which the largest distance between two components is only 1.3 arcsec, was obtained during a period of excellent seeing (0.32 arcsec) measured with a seeing monitor at the top of Paranal. The recorded angular resolution of just 0.38 arcsec demonstrates near-perfect optical quality of the telescope.
3. The Central Area of Globular Cluster M4
This is a colour composite of a field near the centre of the nearest globular cluster. At a seeing of 0.53 arcsec, the blue exposure reaches magnitude B = 24 in only 2 minutes (at signal-to-noise ratio = 5) in a bright sky. A simple extrapolation shows that B ~ 28 would be reached in a 1-hour exposure in a dark sky. The large mirror surface of the VLT UT1 and its ability to produce very sharp images, ensures that faint objects may be observed extremely efficiently.
4. Fine Structure of the Butterfly Nebula
This beautiful colour picture is a composite of three exposures through broad-band blue, green and red filters, lasting a total of 25 minutes. It shows the great complexity of this planetary nebula. It also demonstrates the exceptional efficiency with which features of faint surface brightness can be recorded with the VLT. Strong radiation from a dying star in a binary system at the centre impacts on the surrounding material that has been thrown out earlier from the system.
5) High-velocity Ejecta in Eta Carinae
This fine picture was obtained during an exposure lasting only 10 seconds. It shows fine structures around this very active object in a detail never before achieved with any ground-based telescope. In the lower insert, a short exposure of the central Homunculus Nebula (seeing 0.38 arcsec) provides a clear view of the three-dimensional structure of this bipolar object.
6. The Dust Band in Centaurus A
An amazing amount of faint details is shown in this high-resolution exposure (0.49 arcsec) of the central dust band in the nearby, southern galaxy Centaurus A, obtained through a broad-band red filter and lasting only 10 seconds. The VLT Unit Telescopes will be able to image many other galaxies in similar detail.
7. The Energetic Jet in Messier 87
The First Light took place during the night of May 25 - 26, 1998. Following a short interval of reasonable observing conditions, less optimal atmospheric conditions were encountered. The present photo, a three-colour composite (ultraviolet, blue, green) of the central region of the giant elliptical galaxy Messier 87 in the Virgo Cluster, was obtained during this night.
The 8.2-m main and the 1.1-m secondary mirrors of the VLT Unit Telescopes are completely computer-controlled by means of an Active Optics system. In this way, the shape of the mirror can be optimized very quickly for a given observational purpose. This sequence of 9 images illustrates how the appearance of a stellar image at the focal plane is fully controllable. Fast and thorough optical adjustment ensures the best possible optical quality at all times.
This diagram demonstrates that First Light specifications have been fully met and, more impressively, that the actual VLT performance is sometimes already within the more stringent specifications that were expected to be fulfilled only three years from now.
The final steps before "First Light"
The final, critical testing phase commenced with the installation of the 8.2-m primary (at that time still uncoated) Zerodur mirror and 1.1-m secondary Beryllium mirror during the second half of April. The optics were then gradually brought into position during carefully planned, successive adjustments.
Due to the full integration of an advanced, active control system into the VLT concept, this delicate process went amazingly fast, especially when compared to other ground-based telescopes. It included a number of short test exposures in early May, first with the Guide Camera that is used to steer the telescope. Later, some exposures were made with the Test Camera mounted just below the main mirror at the Cassegrain Focus, in a central space inside the mirror cell. It will continue to be used during the upcoming Commissioning Phase, until the first major instruments (FORS and ISAAC) are attached to the UT1, later in 1998.
The 8.2-m mirror was successfully aluminized at the Paranal Mirror Coating facility on May 20 and was reattached to the telescope tube the day thereafter, cf. ESO PR Photos 13a-e/98 and ESO PR Photos 14a-i/98. Further test exposures were then made to check the proper functioning of the telescope mechanics, optics and electronics.
This has lead up to the moment of First Light, i.e. the time when the telescope is considered able to produce the first, astronomically useful images. Despite an intervening spell of bad atmospheric conditions, this important event took place during the night of May 25 - 26, 1998, right on the established schedule.
Greg Townsend of the University of Akron wrote "Using Telescope Observations in Undergraduate Astronomy Courses" (The Physics Teacher, May 1998, pp. 290-291). He reports on the Stardial telescope at the University of Illinois at Urbana-Champaign, the Bradford Robotic Telescope, the Remotely Operated Telescope of the University of California at Santa Barbara, and the 24-inch reflector at the Mt. Wilson Observatory.
