Zelenchukskaya
Encyclopedia
The Special Astrophysical Observatory , or SAO RAS for short, is an astronomical observatory
, set up in 1966 in the USSR, now operated by the Russian Academy of Sciences
. Based in the Bolshoi Zelenchuk Valley of the Greater Caucasus
near the village of Nizhny Arkhyz, the observatory houses the large BTA-6 optical telescope
and RATAN-600 radio telescope
. The two instruments are about 20 km (12.4 mi) apart.
. The BTA-6 has a prime mirror
diameter of 6 m (236 in) and is housed in a 48 m (157.5 ft) diameter dome at an altitude of 2,070 m (6,791 ft). Seeing first light
in late 1975, it held the record from its completion until 1993, when it was surpassed by the Keck 1
telescope, Hawaii
. Telescopes of comparable or larger size have subsequently employed flexible or segmented mirrors, and the BTA-6 remains the world's largest rigid-mirror telescope until the advent of spin-casting technology (which produced, for example, the single 8.4-meter primary mirror of the Large Binocular Telescope
in the late 1990s). Its altazimuth mounting dictates the need for a field derotation mechanism to maintain the orientation of the field of view
.
Initial results were disappointing due to cracking of the first borosilicate
mirror, which was replaced in 1978. The large housing dome and massive 42 tonne mirror make it difficult to maintain the telescope at a suitable constant temperature during observing sessions. Atmospheric turbulence
caused by windflow over the nearby Caucasus peaks can lead to poor "seeing
" at the site, and observations with an angular resolution
better than an arcsecond are rare. Despite these shortcomings, the BTA-6 remains a significant instrument, able to image objects as faint as the 26th magnitude
.
43°38′48.57"N 41°26′25.61"E
Along with the BTA-6, the SAO operates two smaller telescopes at the BTA site, both built by Carl Zeiss
. Both instruments are used in support of BTA-6 programs, as well as independent observation runs. On the advice of the SAO, programs originally booked for the BTA-6 can be moved to these telescopes, which takes up about 10% of their time.
The larger instrument, the 1 m Zeiss-1000, is located a few hundred meters from BTA-6 in its own building, which consists of a series of offices surrounding the main cylindrical instrument building with the dome on top. First light on the Zeiss-1000 was in 1990, and the installation, including additional instrumentation, was fully completed since 1993.
In 1994 they were joined by a 60 cm Zeiss instrument, formerly part of the Kazan State University's observatory. This is located only a few tens of meters from the Zeiss-1000, in a much simpler building consisting only of the dome and supporting masonry walls.
, which consists of a 576 m diameter circle of rectangular radio reflectors, is also based at the observatory at an altitude of 970 m. Each of the 895 2×7.4 m reflectors can be pointed towards a central conical receiver or to one of five cylindric reflectors. Each reflector is combined with instrumentation cabin. The overall effect is that of a partially steerable antenna with the resolving power of a 600 m diameter dish (when using the central conical receiver), making it the world's largest diameter individual radio telescope.
The RATAN-600 is primarily operated as a transit telescope, in which the rotation of the earth is used to sweep the telescope focus across the subject of observation. Radio frequency
observations can be made in the frequency band 610 MHz to 30 GHz, though primarily in the centimetric waveband, with an angular resolution of up to 2 arcseconds. Observation of the Sun
at radio wavelengths, in particular of the solar corona
, has been a long-standing focus of the RATAN-600's scientific programme. It has also contributed to radio observation for the SETI
project. The RATAN-600 has not been dogged by the technical problems of the neighbouring BTA-6, and has generally been in high demand since its first operations in mid-1974.
43°49′34.20"N 41°35′12.06"E
Observatory
An observatory is a location used for observing terrestrial or celestial events. Astronomy, climatology/meteorology, geology, oceanography and volcanology are examples of disciplines for which observatories have been constructed...
, set up in 1966 in the USSR, now operated by the Russian Academy of Sciences
Russian Academy of Sciences
The Russian Academy of Sciences consists of the national academy of Russia and a network of scientific research institutes from across the Russian Federation as well as auxiliary scientific and social units like libraries, publishers and hospitals....
. Based in the Bolshoi Zelenchuk Valley of the Greater Caucasus
Greater Caucasus
Greater Caucasus , sometimes translated as "Caucasus Major", "Big Caucasus" or "Large Caucasus") is the major mountain range of the Caucasus Mountains....
near the village of Nizhny Arkhyz, the observatory houses the large BTA-6 optical telescope
Optical telescope
An optical telescope is a telescope which is used to gather and focus light mainly from the visible part of the electromagnetic spectrum for directly viewing a magnified image for making a photograph, or collecting data through electronic image sensors....
and RATAN-600 radio telescope
Radio telescope
A radio telescope is a form of directional radio antenna used in radio astronomy. The same types of antennas are also used in tracking and collecting data from satellites and space probes...
. The two instruments are about 20 km (12.4 mi) apart.
BTA-6 optical telescope
The BTA-6 was for several years the world's largest solid-mirror reflecting telescopeReflecting telescope
A reflecting telescope is an optical telescope which uses a single or combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century as an alternative to the refracting telescope which, at that time, was a design that suffered from...
. The BTA-6 has a prime mirror
Mirror
A mirror is an object that reflects light or sound in a way that preserves much of its original quality prior to its contact with the mirror. Some mirrors also filter out some wavelengths, while preserving other wavelengths in the reflection...
diameter of 6 m (236 in) and is housed in a 48 m (157.5 ft) diameter dome at an altitude of 2,070 m (6,791 ft). Seeing first light
First light
In astronomy, first light is the first use of a telescope to take an astronomical image after it has been constructed. This is often not the first viewing using the telescope; optical tests have likely already been performed during daylight to adjust the components...
in late 1975, it held the record from its completion until 1993, when it was surpassed by the Keck 1
Keck telescopes
The W. M. Keck Observatory is a two-telescope astronomical observatory at an elevation of near the summit of Mauna Kea in Hawai'i. The primary mirrors of each of the two telescopes are in diameter, making them the second largest optical telescopes in the world, slightly behind the Gran Telescopio...
telescope, Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
. Telescopes of comparable or larger size have subsequently employed flexible or segmented mirrors, and the BTA-6 remains the world's largest rigid-mirror telescope until the advent of spin-casting technology (which produced, for example, the single 8.4-meter primary mirror of the Large Binocular Telescope
Large Binocular Telescope
Large Binocular Telescope is an optical telescope for astronomy located on Mount Graham in the Pinaleno Mountains of southeastern Arizona, and is a part of the Mount Graham International Observatory...
in the late 1990s). Its altazimuth mounting dictates the need for a field derotation mechanism to maintain the orientation of the field of view
Angle of view
In photography, angle of view describes the angular extent of a given scene that is imaged by a camera. It is used interchangeably with the more general term field of view....
.
Initial results were disappointing due to cracking of the first borosilicate
Borosilicate glass
Borosilicate glass is a type of glass with the main glass-forming constituents silica and boron oxide. Borosilicate glasses are known for having very low coefficients of thermal expansion , making them resistant to thermal shock, more so than any other common glass...
mirror, which was replaced in 1978. The large housing dome and massive 42 tonne mirror make it difficult to maintain the telescope at a suitable constant temperature during observing sessions. Atmospheric turbulence
Turbulence
In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time...
caused by windflow over the nearby Caucasus peaks can lead to poor "seeing
Astronomical seeing
Astronomical seeing refers to the blurring and twinkling of astronomical objects such as stars caused by turbulent mixing in the Earth's atmosphere varying the optical refractive index...
" at the site, and observations with an angular resolution
Angular resolution
Angular resolution, or spatial resolution, describes the ability of any image-forming device such as an optical or radio telescope, a microscope, a camera, or an eye, to distinguish small details of an object...
better than an arcsecond are rare. Despite these shortcomings, the BTA-6 remains a significant instrument, able to image objects as faint as the 26th magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
.
43°38′48.57"N 41°26′25.61"E
Other optical telescopes
Carl Zeiss
Carl Zeiss was a German maker of optical instruments commonly known for the company he founded, Carl Zeiss Jena . Zeiss made contributions to lens manufacturing that have aided the modern production of lenses...
. Both instruments are used in support of BTA-6 programs, as well as independent observation runs. On the advice of the SAO, programs originally booked for the BTA-6 can be moved to these telescopes, which takes up about 10% of their time.
The larger instrument, the 1 m Zeiss-1000, is located a few hundred meters from BTA-6 in its own building, which consists of a series of offices surrounding the main cylindrical instrument building with the dome on top. First light on the Zeiss-1000 was in 1990, and the installation, including additional instrumentation, was fully completed since 1993.
In 1994 they were joined by a 60 cm Zeiss instrument, formerly part of the Kazan State University's observatory. This is located only a few tens of meters from the Zeiss-1000, in a much simpler building consisting only of the dome and supporting masonry walls.
RATAN-600 radio telescope
The RATAN-600 radio telescopeRadio telescope
A radio telescope is a form of directional radio antenna used in radio astronomy. The same types of antennas are also used in tracking and collecting data from satellites and space probes...
, which consists of a 576 m diameter circle of rectangular radio reflectors, is also based at the observatory at an altitude of 970 m. Each of the 895 2×7.4 m reflectors can be pointed towards a central conical receiver or to one of five cylindric reflectors. Each reflector is combined with instrumentation cabin. The overall effect is that of a partially steerable antenna with the resolving power of a 600 m diameter dish (when using the central conical receiver), making it the world's largest diameter individual radio telescope.
The RATAN-600 is primarily operated as a transit telescope, in which the rotation of the earth is used to sweep the telescope focus across the subject of observation. Radio frequency
Radio frequency
Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...
observations can be made in the frequency band 610 MHz to 30 GHz, though primarily in the centimetric waveband, with an angular resolution of up to 2 arcseconds. Observation of the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
at radio wavelengths, in particular of the solar corona
Corona
A corona is a type of plasma "atmosphere" of the Sun or other celestial body, extending millions of kilometers into space, most easily seen during a total solar eclipse, but also observable in a coronagraph...
, has been a long-standing focus of the RATAN-600's scientific programme. It has also contributed to radio observation for the SETI
SETI
The search for extraterrestrial intelligence is the collective name for a number of activities people undertake to search for intelligent extraterrestrial life. Some of the most well known projects are run by the SETI Institute. SETI projects use scientific methods to search for intelligent life...
project. The RATAN-600 has not been dogged by the technical problems of the neighbouring BTA-6, and has generally been in high demand since its first operations in mid-1974.
43°49′34.20"N 41°35′12.06"E
External links
- SAO homepage (English and Russian)
- BTA-6 webcam
- Bolshoi Teleskop Azimutalnyi, by Bill Keel
- Satellite photo of RATAN-600 on Google Maps, centered on the centre of the telescope
- Satellite photo of BTA-6 on Google Maps, centered on the telescope