Astronomy fanatica
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Hat Creek Radio Observatory
The Hat Creek Radio Observatory (HCRO) is operated by the Radio Astronomy Laboratory (an Organized Research Unit of the Astronomy Department at the University of California, Berkeley). It is located approximately 290 miles north-east of San Francisco, in Shasta County, California. It is sited at an elevation of 1,280m.
Hat Creek Radio Observatory, with 85-foot dish and 3-element millimeter array.
History
HCRO was founded in the 1950's by the newly created Radio Astronomy Laboratory. An 85-foot antenna was built in 1960 and operated until 1993, when it collapsed during a wind storm.
Constructing the 85-foot dish
The earliest experiments in millimeter-wave astronomy were performed at this site starting in the 1970s when a 2-element interferometer was constructed. From 1980 to 1985, a 3-element interferometer was constructed, with another 3 antennas added between 1990 and 1992. After the 85-foot dish was lost, another 3 antennas were added to the millimeter array for a total of 9 elements. This came to be known as BIMA. The BIMA telescopes were moved in the spring of 2005 to be combined with other milli-meter antennas as part of the Combined Array for Research in Millimeter-wave Astronomy (CARMA) project and to make way for the Allen Telescope Array (ATA).
Aftermath of 85-foot collapse during a wind storm
Artist rendering of completed ATA-350
Issue #118 -
Astronomy Picture of the Day
2005 June 20
Sunset Over Gusev Crater
Explanation: What would it be like to see a sunset on Mars? To help find out, the robotic rover Spirit was deployed last month to park and serenely watch the Sun dip below the distant lip of Gusev crater. It was a tough job, but some robot had to do it. Now on Earth a red sunset is caused by two effects -- by blue light being preferentially scattered out of sunlight by oxygen and nitrogen molecules in the atmosphere, and by scattering off a small amount of impurities like volcanic dust. (The magnitude of the first effect was computed in one of Albert Einstein's most cited papers.) Although Mars lacks oxygen and nitrogen, it is covered in red dust frequently hoisted into the atmosphere by fast but thin winds. Analyses of images like the above photograph show that at least some Martian days are capped by a sunset significantly longer and redder than typical on Earth. For up to two hours after twilight, sunlight continued to reflect off Martian dust high in the atmosphere, casting a diffuse glow. The result helps atmospheric scientists understand not only the atmosphere of Mars, but atmospheres across the Solar System, including our home Earth.
Credit: Mars Exploration Rover Mission, Texas A&M, Cornell, JPL, NASA -
Lick Observatory
The Lick Observatory is an astronomical observatory, owned and operated by the University of California. It is situated on the summit of Mount Hamilton, in the Diablo Range near San Jose, California, USA. The observatory is managed from the University of California, Santa Cruz, where its scientific staff moved to in the mid-1960s.
The Lick Observatory. The main observatory building and the North (small) Dome, home of the Nickel Reflector
General Information
Organization: University of California
Location: San Jose, California, USA
Coordinates: 37° 20' 35" N 121° 38' 14'' W
Altitude: 1,300 m (4,300 ft)
Weather: 300 clear nights/year
Webpage
Telescopes
C. Donald Shane telescope: 3 m reflector
James Lick telescope: 91 cm refractor
Katzman Automatic Imaging Telescope: 76 cm reflector
Anna L. Nickel telescope: 1 m reflector
Crossley telescope: 0.9 m reflector
Early history
Lick Observatory was the world's first mountain-top observatory.
The observatory was constructed between 1876 and 1887, from a bequest from James Lick. In 1887 Lick's body was buried under the future site of the telescope, with a brass tablet bearing the inscription, "Here lies the body of James Lick."
Before construction could begin, a road to the site had to be built. All of the construction materials had to be brought to the site by horse and mule-drawn wagons, which could not negotiate a steep grade. To keep the grade below 6.5%, the road had to take a very winding and sinuous path, which the modern-day road still follows. Tradition maintains that this road has exactly 360 turns. (This is approximately correct, although uncertainty as to what should count as a turn makes precise verification impossible). Even those who do not normally suffer from motion-sickness find the road challenging.
Original observatory building and the South (main) Dome, home of the Great Lick Refractor
The 91-cm refracting telescope on Mt. Hamilton was Earth's largest refracting telescope from when it saw first light on January 3, 1888, until the construction of Yerkes in 1897. In April, 1888, the observatory was turned over to the Regents of the University of California, and it became the first permanently occupied mountain-top observatory in the world. The location provided excellent viewing performance due to lack of ambient light and pollution; additionally, the night air at the top of Mt. Hamilton is extremely calm, and the mountain peak is normally above the level of the fog that is often seen in the San Francisco Bay Area.
Looking east from south-central San Jose, Lick Observatory atop Mount Hamilton (left) can be seen on reasonably clear days.
With the growth of San Jose, and the rest of Silicon Valley, light pollution became a problem for the observatory. In the 1970s, a site in the Santa Lucia Mountains, southeast of Monterey, was evaluated for possible relocation of many of the telescopes. However, funding for the move was not available, and in 1980 San Jose began a program to reduce the effects of lighting, most notably replacing all streetlamps with low pressure sodium lamps. The result is that the Mount Hamilton site remains a viable location for a major working observatory.
Significant discoveries
The following astronomical objects were discovered at Lick Observatory:
- Several moons of Jupiter
-- Amalthea
-- Ananke
-- Elara
-- Himalia
-- Lysithea
-- Sinope (disputed)
- Several extrasolar planets
-- Triple planet systems
--- Upsilon Andromedae (with Whipple Observatory)
--- 55 Cancri
-- Double planet systems
--- HD38529 (with Keck Observatory)
--- HD12661 (with Keck)
--- GJ876 (with Keck)
--- 47 Ursa Majoris
- Near-Earth asteroid (29075) 1950 DA
Equipment
Current equipment and locations:
- the C. Donald Shane 3 m (120-inch) reflector (Shane Dome, Tycho Brahe Peak)
- the Great Lick 0.9 m (36-inch) refractor (South Dome, Main Building, Observatory Peak)
- the Carnegie 0.5 m (20-inch) twin refractor (Double Astrograph Dome, Tycho Brahe Peak)
- the Anna L. Nickel 1 m (40-inch) reflector (North (small) Dome, Main Building)
- the Crossley 0.9 m (36-inch) reflector (Crossley Dome, Ptolemy Peak)
- the 0.6 m (24-inch) Coude auxiliary telescope (just South of Shane Dome, Tycho Brahe Peak)
- the Tauchmann 0.5 m (22-inch) reflector (Tauchmann Dome atop the water tank, Huyghens Peak)
- CCD Comet Camera 135 mm Nikon camera lens ("The Outhouse" Southwest of the Shane Dome, Tycho Brahe Peak)
- the Katzman Automatic Imaging Telescope (KAIT) 76 cm reflector (24-inch Dome, Kepler Peak)
Issue #119 -
Astronomy Picture of the Day
2005 June 21
The Cygnus Wall of Star Formation
Explanation: The North America Nebula in the sky can do what North Americans on Earth cannot -- form stars. Specifically, in analogy to the Earth-confined continent, the bright part that appears as Central America and Mexico is actually a hot bed of gas, dust, and newly formed stars known as the Cygnus Wall. The above image in representative colors shows the star forming wall lit and eroded by bright young stars, and partly hidden by the dark dust they have created. The part of the North America nebula (NGC 7000) shown spans about 15 light years and lies about 1,500 light years away toward the constellation of Cygnus.
Credit & Copyright: Michael Sherick -
Lowell Observatory
Lowell Observatory is an astronomical observatory in Flagstaff, Arizona. It was founded in 1894 by astronomer Percival Lowell.
Percival Lowell observing Mars from the observer's chair of the 61-centimeter (24-inch) refracting telescope at the Lowell Observatory he established in Flagstaff, Arizona (USA).
The observatory operates nine telescopes at two locations in Flagstaff. The facility at Mars Hill houses the site's original 24-inch (.61-meter) refractor telescope, although its role today is as a public education tool and not research. The telescope, built in 1896 for $20,000, was assembled in Boston by Alvan Clark and then shipped by train to Flagstaff. The telescope is listed as a national historic landmark. The second observation site, at Anderson Mesa, houses four telescopes, including a 72-inch (1.8-meter) Perkins telescope that it shares with Boston University, the 42-inch (1.1-meter) Hall Telescope and the Navy Prototype Optical Interferometer (NPOI). The Perkins telescope was moved to Lowell in 1961 from Perkins Observatory in Delaware, Ohio.
Notable discoveries
- Evidence for the expansion of the universe was discovered between 1912 and 1915
- The planet Pluto was discovered in 1930 by Clyde Tombaugh.
- The planetary ring system of Uranus observed in 1977
Issue #120 -
Astronomy Picture of the Day
2005 June 22
Saturn's Rings from the Other Side
Explanation: What do Saturn's rings look like from the other side? From Earth, we usually see Saturn's rings from the same side of the ring plane that the Sun illuminates them. Geometrically, in the above picture taken in April by the robot Cassini spacecraft now orbiting Saturn, the Sun is behind the camera but on the other side of the ring plane. Such a vantage point gives a breathtaking views of the most splendid ring system in the Solar System. Strangely, the rings have similarities to a photographic negative of a front view. For example, the dark band in the middle is actually the normally bright B-ring. The ring brightness as recorded from different angles indicates ring thickness and particle density of ring particles. Images like these are also interesting for what they do not show: spokes. The unexpected shadowy regions once recorded by the Voyager missions when they passed Saturn in the early 1980s are not, so far, being seen by Cassini. Extra credit: Can you spot the small moon (Prometheus) among the rings?
Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA -
Mauna Kea Observatory
The Mauna Kea Observatory is one of the world's premier astronomical research facilities located on Mauna Kea on the Big Island of Hawai'i, USA. Founded in 1967, the Mauna Kea Observatory is part of the University of Hawai'i System and consists of various multi-national astronomical instruments. Located on a dormant volcano, the facilities are at an altitude of 13,796 feet (4,205 meters) above sea level. The altitude and isolation in the middle of the Pacific Ocean allows for unobstructed views of space without the interference of man-made light sources. The seeing statistics show that Mauna Kea is the second best location for optical and infrared astronomy after Dome C, Antarctica.
The Mauna Kea Observatory, an institute of the University of Hawai'i, is considered one of the most important land-based observatories in the world for its isolated, unobstructed views of space without interference from man-made light sources.
University of Hawaii System Small Seal
Dormitories and a cafeteria are located below the summit at 9,300 feet (2,835 meters) above sea level, and a visitor information station is located at 9,200 feet (2,775 meters). The Mauna Kea Observatory is so high, scientists and other visitors are required to stay at the lower level for a day to acclimate to atmospheric conditions before reaching the summit.
Telescopes
Telescopes found at Mauna Kea Observatory are funded by government agencies of various nations. The University of Hawai'i itself directly administers two telescopes. In total there are twelve telescopes at or around the summit of Mauna Kea.
- California Submillimeter Observatory (CSO): Caltech
- Canada France Hawai'i Telescope (CFHT): Canada, France, University of Hawai'i
- Gemini North Telescope: United States, United Kingdom, Canada, Chile, Australia, Argentina, Brazil
Gemini North telescope is administered by scientists from United States, United Kingdom, Canada, Chile, Australia, Argentina, Brazil.
- Infra-Red Telescope Facility (IRTF): NASA
- James Clerk Maxwell Telescope (JCMT): United Kingdom, Canada, Netherlands
- Subaru Telescope: Japan
The Subaru Telescope and one of the Keck Telescopes.
- Sub-Millimeter Array (SMA): Taiwan, United States
- United Kingdom Infrared Telescope (UKIRT): United Kingdom
- One receiver of the Very Long Baseline Array (VLBA): United States
- W. M. Keck Telescopes: University of California, California Institute of Technology and the NASA
Issue #121 -
Astronomy Picture of the Day
2005 June 23
Moonrise, Cape Sounion, Greece
Explanation: The Moon was full this month on June 22nd, only a day after the northern hemisphere's summer solstice. Since this solstice marked the northernmost point of the Sun's annual motion through planet Earth's sky, the full Moon rising near the ecliptic plane opposite the Sun was at its farthest south for the year. Only a month earlier, on May 23rd, astronomer Anthony Ayiomamitis recorded this picture of another southerly full Moon rising above Cape Sounion, Greece. The twenty-four hundred year old Temple of Poseidon lies in the foreground, also visible to sailors on the Aegean Sea. In this well-planned, single exposure, a long telephoto lens makes the Moon loom large, but even without optical aid casual skygazers often find the full Moon looking astonishingly large when seen near the horizon. That powerful visual effect is known as the Moon Illusion.
Credit & Copyright: Anthony Ayiomamitis -
McDonald Observatory
The McDonald Observatory is located in the Davis Mountains, 450 miles west of Austin, Texas (USA). The observatory is equipped with a wide range of instrumentation for imaging and spectroscopy in the optical and infrared, and operates one of the first lunar ranging stations. McDonald is part of the astronomy program of the University of Texas at Austin.
Aerial view of the McDonald Observatory. The Hobby-Eberly Telescope is seen in the foreground.
The Otto Struve Telescope and the Harlan J. Smith Telescope are located on Mount Locke at an altitude of 6,791 feet. The Hobby-Eberly Telescope, dedicated in late 1997, is located on the summit of Mount Fowlkes at 6,659 feet above sea level. The high and dry peaks of the Davis Mountains make for some of the darkest and clearest night skies in the region and therefore provide excellent conditions for viewing the heavens.
Currently, the observatory operates four research telescopes at its West Texas site:
- 11m Hobby-Eberly Telescope;
- 2.7m Harlan J. Smith Telescope;
- 2.1m Otto Struve Telescope; and
- an 0.8m telescope.
The observatory also hosts one of the four globally networked Robotic Optical Transient Search Experiment (ROTSE) telescopes, and is a Monitoring Network of Telescopes (MONET) site.
History
The McDonald Observatory was originally endowed by the Texas banker William Johnson McDonald (1844 – 1926), who left $800,000 (the bulk of his fortune) to the University of Texas to endow an astronomical observatory.
Issue #122 -
Astronomy Picture of the Day
2005 June 24
Planets in the West
Explanation: This weekend three planets will grace the western sky, forming a lovely trio easily visible shortly after sunset. Saturday evening in particular will find Saturn, Venus, and Mercury all within a 2 degree circle (about the size of your thumb held at arm's length) above the western horizon. Recorded last Sunday, June 19, this image shows the same three planets arrayed along the ecliptic plane above a Colorado Rocky Mountain skyline. Venus is easiest to pick out of the twilight, the brightest celestial beacon below picture center, with Saturn above and to the left of Venus, and Mercury closest to the horizon, right of prominent Pinnacle Peak. By Saturday, the wandering planets will draw even closer together.
Credit & Copyright: Jimmy Westlake (Colorado Mountain College) -
Mount Stromlo Observatory
Mount Stromlo Observatory (MSO) located just outside of Canberra, Australia, is part of the Research School of Astronomy and Astrophysics at the Australian National University (ANU).
Location
Mount Stromlo Observatory is located at an altitude of 770 metres above sea level on Mount Stromlo. Situated west of the centre of Canberra, near the district of Weston Creek. Canberra's main water supply treatment plant is located nearby.
Mount Stromlo Locality Map
History
The observatory was established in 1924 as The Commonwealth Solar Observatory. The site had already been used for observations in the previous decade, with the Oddie telescope being located there in 1911. The dome built to house the Oddie telescope was the first Commonwealth building constructed in the newly established Australian Capital Territory. Until World War II, the observatory specialised in solar and atmospheric observations. After the war, the observatory shifted direction to stellar and galactic astronomy and was renamed The Commonwealth Observatory.
The ANU was established in 1946 in nearby Canberra and joint staff appointments and graduate studies where almost immediately undertaken. A formal amalgamation took place in 1957 with Mount Stromlo Observatory becoming part of the ANU.
Fire
On January 18, 2003 the devastating Canberra firestorm hit Mount Stromlo (surrounded by a plantation pine forest) destroying five telescopes, workshops, seven homes and the heritage listed administration building. The only telescope to escape the fires was the 1868 15-centimetre Farnham telescope.
The old administration building with the dome of the Farnham telescope at the Mount Stromlo Observatory
Redevelopment is now under way with the restoration of several of the heritage buildings, the construction of new workshops, the installation of two new telescopes on Mount Stromlo and a new world class fast sky mapping telescope to be placed at the ANU's other observatory (Siding Springs) but remote controlled via broadband from Mount Stromlo.
Burnt out remains of a telescope
Issue #123 -
Astronomy Picture of the Day
2005 June 25
Venus: Just Passing By
Explanation: Venus, the second closest planet to the Sun, is by far the brightest of the three planets gathered in this weekend's western sky at sunset. It has also proven to be a popular way-point for spacecraft headed for the gas giant planets in the outer reaches of the solar system. Why visit Venus first? Using a gravity assist maneuver, spacecraft can swing by planets and gain energy during their brief encounter, saving fuel for use at the end of their long interplanetary voyage. This colorized image of Venus was recorded by the Jupiter-bound Galileo spacecraft shortly after its gravity assist flyby of Venus in February of 1990. Galileo's glimpse of the veiled planet shows structure in swirling sulfuric acid clouds. The bright area is sunlight glinting off the upper cloud deck.
Credit: Galileo Project, JPL, NASA -
Nice Observatory
The Nice Observatory (Observatoire de Nice) is located in Nice, France on the summit of Mont Gros. The observatory was initiated in 1879 by the banker Raphaël Bischoffsheim. The architect was Charles Garnier, and Gustave Eiffel designed the main cupola.
Nice Observatory - Bischoffsheim cupola (main cupola)
The 76-cm (30-inch) refractor telescope that became operational in 1888 was at that time the world's largest telescope. It was outperformed one year later by the 36-inch (91-cm) refractor at the Lick Observatory.
The 76-cm refractor at Nice Observatory
As a scientific institution, the Nice Observatory no longer exists. It was merged with CERGA in 1988 to form the Côte d'Azur Observatory.
Issue #124 -
Astronomy Picture of the Day
2005 June 26
The 2MASS Galaxy Sky
Explanation: Are the nearest galaxies distributed randomly? A plot of over one million of the brightest "extended sources" detected by the Two Micron All Sky Survey (2MASS) shows that they are not. The vast majority of these infrared extended sources are galaxies. Visible above is an incredible tapestry of structure that provides limits on how the universe formed and evolved. Many galaxies are gravitationally bound together to form clusters, which themselves are loosely bound into superclusters, which in turn are sometimes seen to align over even larger scale structures. In contrast, very bright stars inside our own Milky Way Galaxy cause the vertical blue sash.
Credit & Copyright: 2MASS, T. H. Jarrett, J. Carpenter, & R. Hurt -
Palomar Observatory
Palomar Observatory is a privately-owned observatory located in San Diego County, California, 90 miles (145 km) southeast of Mount Wilson Observatory, on Palomar Mountain. It is owned and operated by the California Institute of Technology (Caltech). The observatory currently consists of four main instruments: the 200 inch (5.08 m) Hale Telescope, the 48 inch (1.22 m) Samuel Oschin Telescope, the 18 inch (457 mm) Schmidt telescope, and a 60 inch (1.52 m) reflecting telescope.
Palomar Observatory
General Information
Organization: Caltech
Location: San Diego County, California, USA
Coordinates: 33° 21' 21 N 116° 51' 50 W
Altitude: 1,713 m (5,618 ft)
Webpage
Telescopes
Hale Telescope: 200 inch (5.08 m) reflector
60 inch Telescope: 60 inch (1.52 m) reflector
Oschin Telescope: 48 inch (1.22 m) Schmidt Reflector
JPL Palomar Testbed Interferometer: Interferometer
Snoop: All-Sky Camera
The Hale Telescope
This 200 inch (5.08 m) telescope is named after astronomer George Ellery Hale. It was built by a Caltech-Carnegie Institution consortium using a Pyrex blank manufactured by Corning Glass Works. The telescope (the largest in the world at that time) saw 'first light' in 1949.
The Hale Telescope is operated by a consortium of Caltech, Jet Propulsion Laboratory, and Cornell University. (See link.)
For a history of the 200 inch (5.08 m) instrument's construction, refer to The Perfect Machine by Ronald Florence.
Palomar Observatory Sky Survey
The Palomar Observatory Sky Survey (POSS), sponsored by the National Geographic institute, was completed in 1958 (The first plates were shot in November 1948 to and the last in April 1958). This survey was performed using 14 inch² or (6 degree)² blue-sensitive (Kodak 103a-O) and red-sensitive (Kodak 103a-E) photographic plates on the 48 inch (1.22 m) Samuel Oschin Schmidt reflecting telescope. The survey covered the sky from a declination of +90 degrees (celestial north pole) to -27 degrees and all right ascensions and had a sensitivity to +22 magnitudes (about 1 million times fainter than the limit of human vision). A southern extension extending the sky coverage of the POSS to -33 degrees declination was shot in 1957 - 1958. The final POSS consisted of 937 plate pairs.
J.B. Whiteoak, an Australian radio astronomer, used the same instrument to extend this survey further south to about -45 degrees declination, using the same field centers as the corresponding northern declination zones. Unlike the POSS, the Whiteoak extension consisted only of red-sensitive (Kodak 103a-E) photographic plates.
Until the completion of the Two Micron All Sky Survey (2MASS), POSS was the most extensive wide-field sky survey ever. When completed, the Sloan Digital Sky Survey will surpass the POSS in depth, although the POSS covers almost 2.5 times as much area on the sky. POSS also exists in digitized form (i.e., the photographic plates were scanned), both in photographic form as the Digital Sky Survey (DSS) (see link) and in catalog form as the Minnesota Automated Plate Scanner (MAPS) Catalog (see link).
Current research
One of the current ongoing research programs at Palomar is the Near-Earth Asteroid Tracking program.
This program makes use of the Palomar QUEST Variability survey (see link) that began in the autumn of 2001 to map a band of sky around the equator. This search switched to a new camera installed on the 48 inch (1.22 m) Samuel Oschin Schmidt Telescope at Palomar in summer of 2003 and the results are used by several projects, including the Near-Earth Asteroid Tracking project. Another program that uses the QUEST results discovered 90377 Sedna on November 14, 2003, and around 40 Kuiper belt objects. Other programs that share the camera are Shri Kulkarni's search for gamma-ray bursts (this takes advantage of the automated telescope's ability to react as soon as a burst is seen and take a series of snapshots of the fading burst), Richard Ellis' search for supernovae to test whether the universe's expansion is accelerating or not, and S. George Djorgovski's quasar search.
The camera itself is a mosaic of 112 CCDs covering the whole (4 degree by 4 degree) field of view of the Schmidt telescope, the largest CCD mosaic used in an astronomical camera at the time.
Issue #125 -
Astronomy Picture of the Day
2005 June 27
Globular Cluster M22 from CFHT
Explanation: The globular cluster M22, pictured above, contains over 100,000 stars. These stars formed together and are gravitationally bound. Stars orbit the center of the cluster, and the cluster orbits the center of our Galaxy. So far, about 140 globular clusters are known to exist in a roughly spherical halo around the Galactic center. Globular clusters do not appear spherically distributed as viewed from the Earth, and this fact was a key point in the determination that our Sun is not at the center of our Galaxy. Globular clusters are very old. There is a straightforward method of determining their age, and this nearly matches the 13.7 billion-year age of our entire universe.
Credit & Copyright: Jean-Charles Cuillandre (CFHT), Hawaiian Starlight, CFHT -
European Southern Observatory
The European Southern Observatory (ESO) is an international astronomical organisation, composed and supported by ten countries from the European Union plus Switzerland and was created in 1962. It is famous for discovering a candidate to be farthest galaxy ever seen by humans, the Abell 1835 IR1916 galaxy, though this claim seems to be debunked by a series of new articles. In 2005, it obtained the first picture of an exosolar planet, 2M1207b, orbiting a brown dwarf 260 light-years away.
Facilities
Most of its observation facilities are located in Chile (hence the name "Southern"), and the headquarters are located in Garching near Munich, Germany. ESO operates three major observatories in the Atacama desert, Chile:
- The La Silla Observatory
- The Paranal Observatory, which includes the Very Large Telescope
- The Atacama Large Millimeter Array under construction in collaboration with the NSF (USA) and the NRC (Canada).
One of the most ambitious ESO projects is the Overwhelmingly Large Telescope (OWL). If built, it will be the largest telescope in the world.
Member countries:
- Belgium
- Denmark
- Finland
- France
- Germany
- Italy
- Netherlands
- Portugal
- Sweden
- Switzerland
- United Kingdom
Observatories Host Country:
- Chile
Instruments at La Silla
Of the eighteen telescopes at La Silla Observatory, three are operated by ESO for use by the ESO astronomical community:
2.2 m telescope
This telescope is loaned from the Max Planck Gesellschaft. Its instrumentation includes both a spectroscope and a wide-field CCD imager capable of mapping substantial portions of the sky in a single exposure.
3.6 m telescope
A conventionally designed horseshoe mount telescope, this is mostly instrumented for infrared spectroscopy.
New Technology Telescope (NTT)
Although the NTT is almost the same size as the 3.6 m telescope, the use of active optics makes it a higher resolution instrument. Also it had, at the time of building, innovative thermal control systems to minimise the telescope and dome seeing.
Instruments at Paranal
The Very Large Telescope (VLT) is the main instrument, composed of four near-identical 8.2 m telescopes. In addition the four main telescopes can combine their light to make a fifth instrument, the VLTI, Very Large Telescope Interferometer. Four auxiliary telescopes of 1.8 m each are being added to the VLTI to make it available when the main telescopes are being used for other projects. The first two of these were installed in early 2004 and 2005.
The site also houses the 2.5 m VLT Survey Telescope and 4 m VISTA survey telescope with wider fields of view for surveying large areas of sky uniformly.
The Very Large Telescope at Paranal
Issue #126 -
Astronomy Picture of the Day
2005 June 28
The Giant Radio Lobes of Fornax A
Explanation: Together, the radio lobes span over one million light years -- what caused them? In the center is a large but peculiar elliptical galaxy dubbed NGC 1316. Detailed inspection of the NGC 1316 system indicates that it began absorbing a small neighboring galaxy about 100 million years ago. Gas from the galactic collision has fallen inward toward the massive central black hole, with friction heating the gas to 10 million degrees. For reasons not yet well understood, two oppositely pointed fast moving jets of particles then developed, eventually smashing into the ambient material on either side of the giant elliptical galaxy. The result is a huge reservoir of hot gas that emits radio waves, observed as the orange (false-color) radio lobes in the above image. The radio image is superposed on an optical survey image of the same part of the sky. Strange patterns in the radio lobes likely indicate slight changes in the directions of the jets.
Credit: Ed Fomalont (NRAO) et al., VLA, NRAO, AUI, NSF -
Royal Greenwich Observatory
The original site of the Royal Greenwich Observatory (RGO), which was built as a workplace for the Astronomer Royal, was on a hill in Greenwich Park in Greenwich, London, overlooking the River Thames. The Prime Meridian, to which longitude refers, went through the observatory. It is marked by a brass strip in the courtyard and, since December 16, 1999, a powerful green laser shining north across the London night sky.
Royal Greenwich Observatory
The observatory was commissioned in 1675 by King Charles II. Flamsteed House (1675-76), the original part of the Observatory, was designed by Sir Christopher Wren and was the first purpose-built scientific research facility in Britain.
The last time that all departments of the RGO were at Greenwich was before World War II. Many departments were evacuated along with the rest of London to the countryside (Abinger, Bradford, and Bath) in 1939. After the War, in 1947, the decision was made to move to Herstmonceux Castle and 320 adjacent acres (1.3 km²) (70 km south-southeast of Greenwich near Hailsham in East Sussex) due to light pollution in London. Although the Astronomer Royal moved to the castle in 1948, the scientific staff could not move until the completion of new observatory buildings in 1957. Shortly thereafter, other far flung departments were reintegrated at Herstmonceux.
Former Royal Greenwich Observatory, Herstmonceux East Sussex
The Isaac Newton Telescope was built there in 1967, but was moved to Roque de los Muchachos Observatory in Spain's Canary Islands in 1979. In 1990 the RGO moved again, to Cambridge. Following a decision of the Particle Physics and Astronomy Research Council, it closed in 1998. Her Majesty's Nautical Almanac Office was transferred to the Rutherford Appleton Laboratory after the closure. Other work went to the UK Astronomy Technology Centre in Edinburgh. The castle now houses the International Study Centre of Queen's University, Kingston, Canada and the Observatory Science Centre.
Greenwich Mean Time was at one time based on the time observations made at Greenwich, before being superseded by Coordinated Universal Time. While Greenwich no longer hosts a working astronomical observatory, it remains a centre of excellence for modern astronomy.
A time ball still drops daily to mark the exact moment of 1 pm (13:00) - this was installed by Astronomer Royal John Pond in 1833. There is a good museum of astronomical and navigational tools, notably including John Harrison's prize-winning longitude chronometer, H4. In February 2005 construction work began on a £15 million redevelopment project which will provide a new planetarium and additional display galleries and educational facilities.
Chronology
-- 1675 Royal Observatory founded.
-- 1924 Hourly time signals (Greenwich Time Signal) from the Greenwich Observatory were first broadcast on February 5.
-- 1948 Astronomer Royal moves to Herstmonceux.
-- 1957 Royal Observatory completes its move to Herstmonceux, becoming the Royal Greenwich Observatory (RGO). The Greenwich site becomes the Old Royal Observatory.
-- 1990 RGO moves to Cambridge.
-- 1998 RGO closes. Greenwich site becomes the Royal Observatory, Greenwich, and is part of the National Maritime Museum.
Issue #127 -
Astronomy Picture of the Day
2005 June 29
Thirteen Million Kilometers from Comet Tempel 1
Explanation: The Deep Impact spacecraft continues to close on Comet Tempel 1, a comet roughly the size of Manhattan. Early on July 3 (EDT), the Deep Impact spacecraft will separate in to two individual robotic spaceships, one called Flyby and the other called Impactor. During the next 24 hours, both Flyby and Impactor will fire rockets and undergo complex maneuvers in preparation for Impactor's planned collision with Comet Tempel 1. On July 4 (1:52 am EDT) if everything goes as scheduled, the 370-kilogram Impactor will strike Tempel 1's surface at over 14,000 kilometers per hour. Impactor will attempt to photograph the oncoming comet right up to the time of collision, while Flyby photographs the result from nearby. The above image was taken on 19 June from about 13 million kilometers out and used to help identify the central nucleus of the comet inside the diffuse coma. Telescopes around the Earth, including the Hubble Space Telescope, will also be closely watching the distant silent space ballet. The result may give crucial information about the structure of comets and the early history of our Solar System.
Credit: U. Md., JPL-Caltech, NASA -
Roque de los Muchachos Observatory
Roque de los Muchachos Observatory is an astronomical observatory located in the municipality of GarafÃa on the island of La Palma. The observatory site is operated by the Instituto de AstrofÃsica de Canarias which is based on nearby Tenerife.
Overview of some of the telescopes at the Roque de los Muchachos Observatory.
General Information
Organization: IAC
Location: La Palma, Canary Islands, Atlantic Ocean (Island owned by Spain)
Coordinates: 28° 46 N, 17° 53 W
Altitude: 2,500 m
Webpage: IAC website
Telescopes
MAGIC (telescope): 17 m gamma-ray imaging Cherenkov telescope
Gran Telescopio Canarias: 10.4 m reflecting telescope
William Herschel Telescope: 4.2 m reflecting telescope
Telescopio Nazionale Galileo: 3.5 m reflecting telescope
Nordic Optical Telescope: 2.56 m reflecting telescope
Isaac Newton Telescope: 2.5 m reflecting telescope
Liverpool Telescope: 2.0 m robotic telescope (also reflecting)
Mercator Telescope: 1.2 m reflecting telescope
Swedish Solar Telescope: 1.0 m refracting vacuum solar telescope
Jacobus Kapteyn Telescope: 1.0 m reflecting telescope
Dutch Open Telescope: 0.45 m reflecting solar telescope
Carlsberg Meridian Telescope: 0.18 m refracting telescope
SuperWASP: 5 wide angle cameras with 0.11 m diameter lenses
HEGRA: 17 Cherenkov telescopes, 3 m diameter now dismantled
The seeing statistics make it the third best location for optical and infrared astronomy after Dome C, Antarctica and Mauna Kea Observatory, Hawaii. The site has some of the premier astronomical facilities in the Northern Hemisphere, including the adaptive optics corrected Swedish Solar Telescope which provides the highest resolution solar imaging of any telescope, and the 10.4 m Gran Telescopio Canarias.
Telescopes at the observatory at sunset
History
The observatory started with the Isaac Newton Telescope, which was moved to La Palma from the Royal Greenwich Observatory site at Herstmonceux Castle in Sussex, England in 1979. The move was beset with difficulties, and it is widely recognised that it would have been cheaper to have built a new telescope rather than moving an existing one.
The observatory was initiated in Santa Cruz de La Palma by representatives from Spain, Sweden, Denmark and the United Kingdom. Other countries became involved later, including Germany, Norway, The Netherlands, Finland, Iceland and the USA.
The observatory was officially inaugurated on the 29th June 1985 by the Spanish royal family and six European heads of state. Seven helicopter pads were built at the observatory to allow the dignatories to arrive in comfort.
Several of the helicopter pads built for the inaugaration ceremony can be seen under the HEGRA array.
Issue #128 -
Astronomy Picture of the Day
2005 June 30
Three Planets from Mt. Hamilton
Explanation: Venus, Mercury, and Saturn wandered close together in western evening skies last week. On Saturnday, June 25, astronomer R. Jay GaBany recorded this snapshot of their eye-catching planetary conjunction, from historic Lick Observatory on Mt. Hamilton, California, USA. The view looks toward the Pacific shortly after sunset with the lights of San Jose and the southern San Francisco Bay area in the foreground. Of course, Venus is the brightest of the trio. Mercury is nearby on the right and Saturn is below and left, closest to the horizon. Farther to the right of the planetary triangle are Pollux and Castor, twin stars of Gemini, with Regulus, bright star of the constellation Leo, at the very upper left corner of the picture. In the coming days, Venus and Mercury remain close, while Saturn continues to drop below them, toward the horizon.
Credit & Copyright: R. Jay GaBany -
Solar and Heliospheric Observatory
The Solar and Heliospheric Observatory (SOHO) is a spacecraft launched in 1995 to study the sun. It is a joint project of the European Space Agency (ESA) and NASA.
Poster with artist's concept of the SOHO spacecraft
General Information
Organization: ESA, NASA
Wavelength regime: optical through UV, also magnetic information
Orbit height: 1.5×10^6 km (heliocentric, sunwards at L1)
Orbit period: 1 year
Launch date: 2 December 1995
Deorbit date: (on going)
Mass: 1,850 kg (610 kg payload)
Webpage
Instruments
GOLF: core oscillations
VIRGO: core oscillations
MDI: oscillations and magnetic fields
SUMER: corona characteristics
CDS: corona characteristics
EIT: UV, low corona
UVCS: UV inner corona spectrograph
LASCO: outer corona spectrograph
SWAN: solar wind density
CELIAS: solar wind ions
COSTEP: solar wind ions
ERNE: solar wind ions
The 610 kg SOHO spacecraft orbits the L1 Lagrange point, the point between the Earth and the Sun where the balance of the (larger) Sun's gravity and the (smaller) Earth's gravity is equal to the centripetal force needed for an object to have the same orbital period in its orbit around the Sun as the Earth, with the result that the object will stay in that relative position. It is about 1.5 million kilometres from the Earth. Gravity from the Sun is 2% (118 µm/s²) more than at the Earth (5.9 mm/s²), while the reduction of required centripetal force is half of this (59 µm/s²). The sum of both effects is balanced by the gravity of the Earth, which is here also 177 µm/s².
Although sometimes described as being at L1, the SOHO satellite is not exactly at L1 as this would make communication difficult (an antenna on Earth focused on SOHO would be "looking" right into the Sun) and is not a stable orbit. Rather it lies in the (constantly moving) plane which passes through L1 and is perpendicular to the line connecting the sun and the Earth. It stays in this plane, describing on the plane an elliptical orbit centered about L1. It orbits L1 once every six months, while L1 itself orbits the sun every 12 months as a direct consequence of the motion of the Earth. This keeps SOHO at a good position for communication with Earth at all times.
In normal operation the spacecraft transmits a continuous 200 kbit/s data stream of photographs and other measurements via the NASA Deep Space Network of receiving stations. SOHO's data about solar activity are used to predict solar flares, so electrical grids and satellites can be protected from their damaging effects.
Large solar flare recorded by SOHO EIT304 instrument in the ultraviolet.
In 2003 ESA reported the failure of one of the antenna steering motors, necessary for pointing the antenna to allow SOHO to direct the high bandwidth data at the Earth, might cause two to three week data-blackouts every three months. However, ESA and DSN scientists managed to use SOHO's low gain antenna together with the larger 34 and 70 metre DSN ground stations and judicious use of SOHO's data recorder to prevent any total loss of data, with only a slightly reduced data flow every three months.
Instruments
SOHO contains twelve main instruments, each capable of independently observing the sun or parts of the sun. These are:
- Global Oscillations at Low Frequencies (GOLF) which measures velocity variations of the whole solar disk to explore the core of the sun.
- Variability of Solar Irradiance (VIRGO) which measures oscillations and solar constant both of the whole solar disk and at low resolution, again exploring the core of the sun.
- Michelson Doppler Imager (MDI) which measures velocity and magnetic fields in the photosphere to learn about the convection zone which forms the outer layer of the interior of the sun and about the magnetic fields which control the structure of the corona. See also Helioseismology.
- Solar UV Measurement of Emitted Radiation (SUMER) which measures plasma flows, temperature and density in the corona.
- Coronial Diagnostic Spectrometer (CDS) which measures density, temperature and flows in the corona.
- Extreme UV Imaging Telescope (EIT) which studies the low coronial structure and activity.
- UV Coronagraph and Spectrometer (UVCS) which measures density and temperature in the corona.
- Large Angle Spectrometer Coronagraph (LASCO) which studies the structure and evolution of the corona
- Solar Wind Anisotropies (SWAN) which uses telescopes sensitive to a characteristic wavelength of hydrogen to measure the solar wind mass flux, map the density of the heliosphere, and observe the large-scale structure of the solar wind streams.
- Charge, Element, Isotope Analysis (CELIAS) which studies the ion composition of the solar wind.
- Suprathermal & Energetic Particle Analyser (COSTEP) which studies the ion and electron composition of the solar wind.
- Energetic Particle Analyser (ERNE) which studies the ion and electron composition of the solar wind.
SOHO's instruments observe the Sun (upwards) while the high gain antenna between the solar panels sends results to the Earth (downwards in this diagram).
Observations from some of the instruments can be formatted as images, most of which are also readily available on the internet for either public or research use (see the official website). Others such as spectra and measurements of particles in the solar wind do not lend themselves so readily to this. These images range in wavelength or frequency from optical (H-alpha) to extreme ultraviolet (UV). Images taken partly or exclusively with non-visible wavelengths are shown on the SOHO page and elsewhere in false color. Unlike many space-based and ground telescopes, there is no time allocated for proposals: due to the precise nature of this space observatory, there is no need for such a process.
Issue #129 -
Astronomy Picture of the Day
2005 July 1
Ring Around Fomalhaut
Explanation: Fomalhaut (sounds like "foam-a-lot") is a bright, young, star, a mere 25 light-year trip from planet Earth in the direction of the constellation Piscis Austrinus. Earlier infrared observations identified a torus of cold material surrounding the nearby star but the panels above detail the sharpest ever visible light-image of Fomalhaut's dusty debris ring, recorded by the Hubble Space Telescope's ACS camera. Overwhelming glare from the star is masked by an occulting disk in the camera's coronagraph. The off-center ring with a sharp inner boundary is taken to be strong evidence of a massive planet orbiting far from Fomalhaut, shaping and maintaining the ring's inner edge. Starting 133 astronomical units (Earth-Sun distances) from Fomalhaut, the dusty ring itself is likely a larger, younger analog of our own Kuiper Belt - the solar system's outer reservoir of icy bodies.
Credit: P. Kalas, J. Graham (UC Berkeley), M. Clampin (GSFC), ESA, NASA -
Southern African Large Telescope
The Southern African Large Telescope (SALT) will be an 11 metre (36 feet) diameter optical telescope, located in the semi-desert region of the Karoo, in South Africa. It will be a facility of the South African Astronomical Observatory, the national optical observatory of South Africa.
3D computer model of the Southern African Large Telescope (SALT) outside view. The observatory will have the biggest telescope in the southern hemisphere of the Earth — from where galaxies can be viewed which cannot be seen up north. SALT will probe quasars and enable scientists to view stars and galaxies a billion times too faint to be visible to the naked eye.
SALT will be the biggest telescope in the southern hemisphere. It will enable photography and analysis of the radiation from astronomical objects out of reach of northern hemisphere telescopes. The telescope is projected to be completed in November 2005 at a cost of roughly $30 million USD. Germany, Poland, the United States, the United Kingdom and New Zealand are partners in the project.
General information
SALT will be built on a hilltop in a nature reserve, 370 km (230 miles) northeast of Cape Town, near the small town of Sutherland. In March 2004, installation of the massive mirror began. It will be filled with 91 smaller mirrored hexagons.
Korea and Japan have telescopes at the site and South Africa has at least five optical telescopes there. The University of Birmingham has a solar telescope to help monitor the Sun around the clock.
SALT will probe quasars and enable scientists to view stars and galaxies a billion times too faint to be seen by the naked eye.
Partners
- The National Research Foundation of South Africa
- Nicolaus Copernicus Astronomical Centre of the Polish Academy of Sciences
- The Hobby-Eberly Telescope Board
- Rutgers, the State University of New Jersey
- Georg-August-Universität Göttingen
- The University of Wisconsin-Madison
- University of Canterbury (New Zealand)
- University of North Carolina at Chapel Hill
- Dartmouth College
- Carnegie Mellon University
- United Kingdom SALT Consortium (UKSC), comprising:
-- Armagh Observatory
-- Keele University
-- University of Central Lancashire
-- University of Nottingham
-- Open University
-- University of Southampton
Issue #130
