The Special Astrophysical Observatory of the Russian Academy of Science (SAO RAS; russian: Специальная Астрофизическая Обсерватория) is an astronomical

observatory An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysical, oceanography and volcanology are examples of disciplines for which observatories have been constructed. ...

, set up in 1966 in the

USSR The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nati ...

, and now operated by the

Russian Academy of Sciences The Russian Academy of Sciences (RAS; russian: Росси́йская акаде́мия нау́к (РАН) ''Rossíyskaya akadémiya naúk'') consists of the national academy of Russia; a network of scientific research institutes from across t ...

. Based in the Bolshoi Zelenchuk Valley of the

Greater Caucasus The Greater Caucasus ( az, Böyük Qafqaz, Бөјүк Гафгаз, بيوک قافقاز; ka, დიდი კავკასიონი, ''Didi K’avk’asioni''; russian: Большой Кавказ, ''Bolshoy Kavkaz'', sometimes translat ...

near the village of Nizhny Arkhyz, the observatory houses the

BTA-6 The BTA-6 (russian: Большой Телескоп Альт-азимутальный, translit=Bolshoi Teleskop Alt-azimutalnyi, translation=Large Altazimuth Telescope) is a aperture optical telescope at the Special Astrophysical Observatory lo ...

and

RATAN-600 The RATAN-600 (russian: РАТАН-600 – радиоастрономический телескоп Академии наук – 600, an acronym for the " Academy of Sciences Radio Telescope – 600") is a radio telescope in Zelenchukskaya, ...

, an

optical Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultravio ...

and

radio telescope A radio telescope is a specialized antenna and radio receiver used to detect radio waves from astronomical radio sources in the sky. Radio telescopes are the main observing instrument used in radio astronomy, which studies the radio frequency ...

, respectively. The two instruments are about apart.

BTA-6 optical telescope

The

(Bolshoi Teleskop Altazimutalny; , or Large Altazimuth Telescope), with first light in 1975, was for several years the world's largest single primary mirror optical

reflecting telescope A reflecting telescope (also called a reflector) is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century by Isaac Newton as an alternati ...

. The BTA-6's

primary mirror A primary mirror (or primary) is the principal light-gathering surface (the objective) of a reflecting telescope. Description The primary mirror of a reflecting telescope is a spherical or parabolic shaped disks of polished reflective meta ...

has a diameter of 6 metres (236 inches) and is housed in a 48 m (157.5 ft) diameter dome at an altitude of 2,070 m (6,791 ft). It held the record from its completion until 1993, when it was surpassed by the Keck 1 telescope,

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

. Telescopes of comparable or larger size have subsequently employed flexible or segmented mirrors, and the BTA-6 remained 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 The Large Binocular Telescope (LBT) is an optical telescope for astronomy located on Mount Graham, in the Pinaleno Mountains of southeastern Arizona, United States. It is a part of the Mount Graham International Observatory. When using both ...

in the late 1990s). Its

altazimuth mount An altazimuth mount or alt-azimuth mount is a simple two- axis mount for supporting and rotating an instrument about two perpendicular axes – one vertical and the other horizontal. Rotation about the vertical axis varies the azimuth (compass b ...

dictates the need for a field derotation mechanism to maintain the orientation of the

field of view The field of view (FoV) is the extent of the observable world that is seen at any given moment. In the case of optical instruments or sensors it is a solid angle through which a detector is sensitive to electromagnetic radiation. Human ...

. Initial results were disappointing due to cracking of the first

borosilicate Borosilicate glass is a type of glass with silica and boron trioxide as the main glass-forming constituents. Borosilicate glasses are known for having very low coefficients of thermal expansion (≈3 × 10−6 K−1 at 20 °C), ...

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 In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ...

caused by windflow over the nearby Caucasus peaks can lead to poor seeing at the site, and observations with an

angular resolution Angular 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, thereby making it a major determinant of image resolut ...

better than an

arcsecond A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The n ...

are rare. Despite these shortcomings, the BTA-6 remains a significant instrument, able to image objects as faint as the 26th magnitude. Обсерватория

Other optical telescopes

Along with the BTA-6, the SAO operates two smaller telescopes at the BTA site, both built by

Carl Zeiss AG Carl Zeiss AG (), branded as ZEISS, is a German manufacturer of optical systems and optoelectronics, founded in Jena, Germany in 1846 by optician Carl Zeiss. Together with Ernst Abbe (joined 1866) and Otto Schott (joined 1884) he laid th ...

. 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 in 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

(russian: РАТАН-600 – РАдио Телескоп Академии Наук, or the ''Academy of Science Radio Telescope''), which consists of a 576 m diameter circle of rectangular radio reflectors, is also based at the observatory at an altitude of 970 m. (Coordinates .) Each of the 895 2×7.4 m reflectors can be pointed towards a central conical secondary mirror, or to one of five parabolic cylinders. Each reflector is combined with an instrumentation cabin containing various receivers and instruments. 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 telescope can operate in three modes:The RATAN-600 Radio Telescope
- Russian Academy of Science, Special Astrophysical Observatory * Two-mirror system: An sector of the ring focuses waves to a cylindrical secondary mirror and further onto the receivers * Three-mirror system: The linear plane mirror reflects the waves to the south sector of the ring, which in turn focuses on a cylindrical secondary and onto the receivers (Periscope mirror of Kraus-type system) * Entire ring: For observations near the zenith the entire ring can be used, together with the conical secondary mirror and its receivers Independent observations at various discrete azimuths are possible simultaneously: For this a sector of the ring is used with one of the secondary mirror and receiver units, the later which can be positioned on railway tracks – meanwhile another sector in conjunction with another secondary mirror can be used for an independent observation. At a wavelength of 8 cm, the effective collecting area of the entire ring is with a resolving power in the horizontal plane of 1 arcminute. The RATAN-600 is primarily operated as a

transit telescope In astronomy, a transit instrument is a small telescope with extremely precisely graduated mount used for the precise observation of star positions. They were previously widely used in astronomical observatories and naval observatories to meas ...

, in which the rotation of the earth is used to sweep the telescope focus across the subject of observation.

Radio frequency Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the up ...

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 A corona ( coronas or coronae) is the outermost layer of a star's atmosphere. It consists of plasma. The Sun's corona lies above the chromosphere and extends millions of kilometres into outer space. It is most easily seen during a total solar ...

, has been a long-standing focus of the RATAN-600's scientific programme. It has also contributed to radio observation for the

SETI The search for extraterrestrial intelligence (SETI) is a collective term for scientific searches for intelligent extraterrestrial life, for example, monitoring electromagnetic radiation for signs of transmissions from civilizations on other pl ...

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.

References

References and further reading

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External links