Zelenchukskaya

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Zelenchukskaya (Russian: Зеленчукская) is the Caucasus Mountains site of the Special Astrophysical Observatory (Специальная Астрофизическая Обсерватория) of the Russian Academy of Sciences. Zelenchuk itself is a small village around 40 km distant; the majority of the science staff live at the purpose-built town of Nizhniy Arkhyz (Нижний Архыз). The nearest large city and transport hub is Mineralnye Vody.

1 BTA-6 optical telescope
2 RATAN-600 radio telescope
3 See also
4 External links
5 References and further reading

[edit] BTA-6 optical telescope

The observatory was for a while the world's largest solid-mirror reflecting telescope, known as the BTA-6 (Большой Телескоп Азимутальный, or Large Altazimuth Telescope). The BTA-6 has a prime mirror diameter of 6 m and is housed in a 48 m diameter dome at an altitude of 2,070 m. Seeing first light in late 1975, it held the record for the largest telescope in the world from its completion until 1993 when it was surpassed by the Keck 1 telescope in Hawaii. The altazimuth mounting of the BTA-6 dictates the need for a field derotation mechanism to maintain the orientation of the field of view.

Initial results were disappointing due to the poor optics and even cracking of the first borosilicate mirror, and this 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.

The historical troubles of the BTA-6 were sufficient for James Oberg to include it in his 1988 book Uncovering Soviet Disasters. Despite these shortcomings, the BTA-6 remains a significant astronomical instrument and is still in operational use, able to image objects as faint as the 26th magnitude.

Supplementary observations are made with a pair of 1 m and 0.6 m Carl Zeiss telescopes adjacent to the BTA-6.

[edit] RATAN-600 radio telescope

The RATAN-600 radio telescope (Russian: РАТАН-600 - РАдиоТелескоп 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. Each of the 895 2×7.4 m reflectors can be pointed towards a central conical receiver or to one of 5 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 obervations 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.