The largest telescope in Russia - I want to know. Photo view from Ilya BIM

My old dream came true. Last weekend I visited the territory of the Northern Administrative District. A special astrophysical observatory is located at the foot of Mount Pastukhov in the Zelenchuksky district of the Karachay-Cherkess Republic of Russia. We stopped here on the way to Arkhyz. Currently, the observatory is the largest Russian astronomical center for ground-based observations of the Universe.

01. The main instruments of the observatory are: the BTA optical telescope (Big Azimuthal Telescope) with a main mirror diameter of 6 m and the RATAN-600 radio telescope (Radio Telescope of the Academy of Sciences) with a ring multi-element antenna with a diameter of 600 m. RATAN-600 is located near the village of Zelenchukskaya and its It is clearly visible from the road and, by the way, it is the largest radio telescope in the world. And we will look at the BTA, to travel you just need to show your car documents at the checkpoint.

02. From the checkpoint the drive is about 17 km. The road is of fairly good quality, the elevation gain is about 600 meters. The weather was rainy and this only added color to the surrounding landscapes.

03. The Bolshoy Zelenchuk River meanders below.

05. And all around is full of meadow flowers.

07. BTA with a mirror diameter of 6 meters is the largest optical telescope in Eurasia. Excursions to the BTA are conducted on Fridays, Saturdays, Sundays and calendar holidays from 9.30 to 16.00 (the last excursion starts at 15.30). The duration of the excursion is 40 minutes, the minimum number is 10 people in a group. Naturally, you can also go on a night excursion, provided there is no cloud cover. Using the CELESTRON telescope, with a lens diameter of 280 mm and a maximum magnification of 660 times, it will be possible to observe the night sky. Since we came together, we were not able to go on the excursion. Well, okay, now we know where and how to go. Let's take a walk around the territory.

08. Futuristic

09. The starry sky that we were able to see :)

11. On March 25, 1960, the Council of Ministers of the USSR adopted a resolution on the creation of a reflecting telescope with a main mirror with a diameter of 6 m. And already on November 3, 1974, the telescope was put into trial operation. During this time, an incredible amount of work was done. It's hard to imagine, it's better to see it with your own eyes. The focal length of the mirror is 24 m, the weight of the mirror excluding the frame is 42 tons, the mass of the moving part of the telescope is about 650 tons, the total mass of the telescope is about 850 tons. The mirror was transported on a special trailer, part of the way by water. Some roads in Karachay-Cherkessia had to be expanded specifically for this purpose.

14. For repair work, a gantry crane with a height of 65 meters is used

17. Nearby there are two more telescopes with mirror diameters of 1 m and 0.6 m.

18. The height of the dome is 53 meters.

19. The BTA was the largest telescope in the world from 1975, when it surpassed the five-meter Hale telescope at the Palomar Observatory, until 1993, when the ten-meter telescope at the Keck Observatory became operational.

20. Not far from BTA there is a town for employees to live.

21. On the way back we hit a real cloud. Later I’ll tell you how you can have a good time sleeping in Arkhyz.

More information about the CAO can be found on their official website -

The BTA telescope is the largest optical telescope in Eurasia, the largest telescope in Russia. The full name and abbreviation is as follows: B big T telescope A lt-Azimuthal.

The diameter of the mirror is 6 meters.

Installed at the foot of Mount Pastukhov at an altitude of 2070 m above sea level. Karachay-Cherkessia. It has been operating since 1966.

Back in 1975, the telescope was considered the largest in the world, surpassing the Hale Telescope at the Palomar Observatory (California) in its parameters and technical capabilities. But in 1993, the palm, so to speak, was taken by the ten-meter telescope of the American Keck Observatory, located on the peak of Mauna Kea (4145 meters above sea level), on the island of Hawaii. And it is not surprising that with such funds invested in the project (more than $70 million), by astronomical standards it turned out to be a real giant in scientific space research.

The question is, why did Russia allow the Americans (or whatever we are not used to calling them) to be more far-sighted than our projects and developments in this matter? Why were Soviet developments and megaprojects the best in the whole world, while projects of the post-Soviet era are just gaining momentum, rising from their knees? Fortunately, at least they are rising. However, I don’t remember that in Rosnauk there were as many charitable foundations or philanthropists-virtues as in the states. But they could shake some bunch of oligarchs with their billions... The amounts are not so exorbitant, taking into account the luxurious villas and yachts, islands and other senseless investments of some of the Russian representatives of the “powers that be”...

By the way, in 1985, the Americans attracted funds from the William Myron Keck Charitable Foundation, which, in fact, financed the entire project with a substantial check of more than $70 million. The Foundation was founded in 1954 by William Myron Keck (1880-1964) and today specializes in supporting scientific discoveries and new technologies. And this is what they came up with:

However, returning to our telescope, the BTA remained the telescope with the world's largest monolithic mirror until 1998. But the most interesting information included in the list of really cool things is that to this day the BTA dome is the largest astronomical dome in the world. Well, at leastOur dome (!) is the best in the world.

So that they understand me correctly, there are no goals and objectives to admire alone, and to throw pseudo-dirt at your own... No! I would like it to be humane, that they invest more in science than in weapons, more than in the “priority” showdown with pipes from Gazprom, figuring out which flow is better - northern, southern or some other... I want them to invest more than other states. And maybe scientists won’t go anywhere? - And what? I want to believe...

So, the BTA telescope, as one of the most significant inventions, the pride of Soviet scientists and engineers, went to Russia, as the legal successor of the USSR. What would we like to know about him? I tried to find and compress the information into something more or less digestible and interesting.

1. LYTKARI OPTICAL GLASS

There are only five countries in the world that can produce the full range of optical glass: Russia, Germany, China, USA and Japan. The Lytkarino plant is known primarily for its large-sized optics. Its mirrors are installed on the largest telescopes around the world. One of these mirrors from the plant was installed on the BTA telescope, which actually made it possible to receive the title in two categories at once - “the largest mirror in Eurasia” and “the largest telescope in Eurasia”... One complements the other.

I almost forgot, the weight of the mirror is just over 40 tons. Despite the fact that the mass of the moving part of the telescope is about 650 tons, and the total mass of the telescope is about 850 tons.

There was information that in 2015 the mirror was supposed to be replaced with an updated one - weighing 75 tons, but I did not find information about the work done over the past year, even on the official website of the Lytkarinsky plant. It was only reported that they should do this:

“Next year (editor’s note - in 2015), in May, we will ship a 75-ton mirror for a large azimuthal telescope. According to technology, such a mirror should cool for a year and a half after smelting. This is the largest mirror made for a telescope; the machine for polishing it at the Lytkarino optical glass plant is almost 12 floors high,” said Sergei Maksin, general director of the Shvabe holding, at the international exhibition Oboronexpo.

Photo: SAO RAS archive

2. What is unique?

By technical standards in the 60-70s, the development was considered revolutionary. There were no analogues to the project. The mechanics of the telescope served as the prototype for all subsequent telescopes. All telescopes, even smaller ones, began to be made according to the BTA model.

By the way, the name of the telescope was predetermined. After all, the telescope is not static, it has two axes - vertical and horizontal. They allow you to rotate the structure along the axis and azimuth. Hence the name - B big T telescope A lt-Azimuthal.

In Soviet times, in addition to a huge staff of several hundred people, the operation of the telescope was also monitored by a huge large-sized computer, which now stands in the observatory museum. Over time, the sensors and control system were modernized, but the mechanics remained. Soviet technology is not a piece of cake for you... It was made to last.

3. Staff

According to astronomer Alexei Moiseev, about 400 people now work at the observatory.

“...we have one of the highest percentages of non-scientific personnel among the institutes of the Russian Academy of Sciences - engineers, technicians. We have two main telescopes: the six-meter BTA and the Ratan-600 radio telescope. They need people to serve them. In our country, the downtime of telescopes for technical reasons is measured in only hours per year - this is very little.

By the way, an academic town was built not far from the observatory, where today about 1,200 people live - scientists with their families. Despite protests against the construction of the town from the first director of the observatory, Ivan Kopylov, it was decided to build. And the protest was as follows: astronomers are not geologists, there is no need to force them to work on a rotational basis.

Today, one of the biggest problems on the campus is medical care. As it turned out, as a result of the reform of the Russian Academy of Sciences in 2015, the Federal Agency for Scientific Organizations refuses to support the local outpatient clinic, and the nearest hospital is 30 km away on a mountain road. Question: are you crazy? On the one hand, you raise questions about why there is such a large brain drain, on the other hand, you are pushing yourself out of the country under such conditions...

It is an axiom: in any country in the world, an astronomer with good knowledge and training can find many areas where he will earn more than in science. The country will not move to a new level based on enthusiasm and stupid reforms...

In conclusion, I recommend looking through a large number of high-quality photographs about the BTA telescope. I also recommend watching a short video from the Roscosmos Television Studio. There - on the Roscosmos channel, there are a lot of interesting video reviews - for the most inquisitive. In the meantime, here are some short facts about the BTA telescope:

BTA dome

BTA (“Large Azimuthal Telescope”) is the largest optical telescope in Eurasia with a diameter of the main monolithic mirror of 6 m. Installed at the Special Astrophysical Observatory.

It was the largest telescope in the world from 1975, when it surpassed Palomar Observatory's 5-meter Hale Telescope, until 1993, when it operated with a 10-meter segmented mirror. Nevertheless, the BTA remained the telescope with the world's largest monolithic mirror until its commissioning in 1998 (diameter 8.2 m). To this day, the BTA mirror is the largest in the world by mass, and the BTA dome is the largest astronomical dome in the world.

Device

The BTA is a reflecting telescope. The main mirror with a diameter of 605 cm has the shape of a paraboloid of revolution. The focal length of the mirror is 24 meters, the weight of the mirror excluding the frame is 42 tons. The optical design of the BTA provides for operation in the main focus of the main mirror and two Nesmith focuses. In both cases, an aberration corrector can be used.

The telescope is mounted on an alt-azimuth mount. The mass of the moving part of the telescope is about 650 tons. The total mass of the telescope is about 850 tons.

Chief designer - Doctor of Technical Sciences Bagrat Konstantinovich Ioannisiani (LOMO).

The main mirror of a telescope has significant temperature inertia, which leads to deformation of the mirror and distortion of its working surface. To reduce the influence of temperature effects on image quality, the telescope tower was initially equipped with a ventilation system for the dome space. Currently, cooling units are installed in the tower, designed, if necessary, to artificially lower the temperature of the telescope’s main mirror in accordance with the current weather forecast.

The reflective coating of the mirror is made of unprotected aluminum 100 nanometers thick. The technology for aluminizing the telescope's main mirror, developed by the manufacturer, provided for replacing the working layer of aluminum every 3-5 years. By improving the units of the vacuum mirror aluminizing unit (VUAZ-6), the service life of the mirror layer was increased to an average of 10 years. The last time the aluminum layer of the BTA main mirror was changed was in July 2015.

Modernization

On May 11, 2007, transportation of the first main mirror of the BTA to LZOS, which manufactured it, began for the purpose of deep modernization. The telescope now has a second primary mirror installed. After processing in Lytkarino - removing 8 millimeters of glass from the surface and repolishing, the telescope should be among the ten most accurate in the world. SAO expected that the updated mirror, after a repair costing 5 million euros, would return to the observatory in mid-2013. In 2018, it is planned to install a new, 40-ton mirror manufactured at the Lytkarino optical glass plant.

Location

The telescope is installed at the Special Astrophysical Observatory (SAO) on Mount Semirodniki at the foot of Mount Pastukhov (2733 m) near the village of Nizhny Arkhyz, Zelenchuk region, Karachay-Cherkess Republic, Russian Federation, at an altitude of 2070 m above sea level.

Story

Built for the Pulkovo Observatory in 1878 and installed in 1885, the 76-centimeter refracting telescope became the largest in the world at one time. Due to the specifics of the tasks of the Pulkovo Observatory (in particular, precise time), it did not need large reflectors. In 1926, at the Simeiz Observatory, on Mount Koshka, a meter-long English reflector was installed.

In 1961, the ZTSH-2.6 telescope, manufactured at the State Optical-Mechanical Plant, with a mirror diameter of 2.6 meters - the largest telescope in the USSR and Europe - was launched at the Crimean Astrophysical Observatory. By that time, scientists had developed a 5-meter telescope and were thinking about a 6-meter one, and the RATAN-600 radio telescope was on the way. It was decided to place both instruments side by side, so a new location for the observatory was required. Good locations are in the Central Asian republics of the former USSR, but a political decision was made to place the instrument in the RSFSR.

Officially, the decision of the USSR Government to create a 6-meter telescope in the country was announced by A. N. Kosygin in his speech at the 10th General Assembly of the International Astronomical Union, held in 1958 in Moscow.

On March 25, 1960, the Council of Ministers of the USSR adopted a Resolution on the creation of a reflecting telescope with a mirror with a diameter of 6 meters. The main work was entrusted to the Leningrad Optical-Mechanical Plant, the Lytkarinsky Optical Glass Plant (LZOS), and the State Optical Institute named after. S.I. Vavilov (GOI), as well as a number of other enterprises.

The Lytkarino optical glass plant was approved as the main contractor for the development of the technological process for casting a mirror blank with a diameter of 6 m and for the production of a mirror blank. It was necessary to cast a glass blank weighing 70 tons, anneal it and carry out complex processing of all surfaces with the production of a central through hole and more than 60 mounting blind holes on the back side.

Over the course of three years, a special building of a pilot production workshop was designed and built for the production of the BTA blank, the task of which included installation and debugging of equipment, development of the industrial technical process and production of the mirror blank. The main equipment of the workshop was unique and had no analogues.

Specialists from LZOS and GOI conducted research and developed a glass composition that met the specified requirements. As a result of the work carried out, a technological process was developed, agreed with GOI, according to which a trial production and experimental casting of a workpiece with a diameter of 6200 mm was carried out. All operating modes and techniques, as well as the organization of low tide, were tested on this experimental workpiece. A technological process was drawn up for casting a standard billet.

In November 1964, the first blank of the main mirror was cast, which was annealed, that is, slowly cooled at a given mode, for more than 2 years. To process this workpiece, it was necessary to remove about 25 tons of glass. The existing experience in processing large-sized workpieces turned out to be unsuitable, a decision was made to use diamond equipment, and a set of works to create optimal processing modes made it possible to develop and implement a technology for manufacturing an industrial workpiece of the main mirror. Processing of the workpiece was carried out for almost a year and a half on a special rotary machine created at the Kolomna Heavy Machine Tool Plant. To obtain a workpiece of a given geometric shape, a complex of diamond tools was designed, where over 12,000 carats of natural diamonds in powder form were used. 7,000 carats of diamonds were used to remove 28 tons of stock, grind and polish the side surface. It was difficult to mark and process 66 blind holes to accommodate the mirror unloading mechanisms. The mass of the workpiece, calculated based on the actual dimensions, was about 42 tons. The workpiece was accepted for further processing of the front side in September 1968.

Precise processing of the mirror was carried out by LOMO specialists in a special temperature-controlled housing on a unique grinding machine manufactured by the Kolomna Plant. In January 1969, the mirror was polished to obtain a spherical surface; by June 1974, polishing was finally completed, and the mirror was prepared for certification.

The creation of this unique mirror lasted almost 10 years.

In 1968, Glavmosavtotrans delivered large parts of the telescope to the observatory. In 1969, a unique vacuum installation for aluminizing the main mirror was delivered.

In June 1974, transportation of the mirror began. After production, it was preserved with a special protective film and installed in a special transport container. Given its exceptional value, extreme precautions were taken during its transportation. It was decided to conduct a trial transportation of the mirror simulator along the entire route, which was carried out from May 12 to June 5, 1974. Based on the results, technical conditions for transporting the mirror were developed. The trailers with the container and frame were installed on a barge, secured and, with the help of a powerful tug, delivered through the Moscow-Volga canal, along the Volga and the Volgo-Don canal to Rostov-on-Don. Then the trailers delivered it along the roads of the North Caucasus to the village of Zelenchukskaya to the Special Astrophysical Observatory (SAO).

It was sent at the end of June, delivered to the observatory in August 1974 and installed in the frame in September - October. After trial operation during the winter of 1974/75 and the spring of 1975, training of operating personnel and other work, on December 30, 1975, the act of the State Interdepartmental Commission for the acceptance of the Large Azimuth Telescope was approved, and the telescope was put into operation.

A second mirror was later manufactured and delivered in August 1978; in 1979 it was aluminized and installed on the telescope.

Problems

As with other large telescopes, a big problem is thermal deformation of the main mirror. For the BTA, this problem is especially acute due to the large mass and thermal inertia of the mirror and dome. If the temperature of the mirror changes faster than 2° per day, the resolution of the telescope drops by one and a half times. To increase the duration of observation time, the temperature of the telescope room is regulated using an air conditioning system, and is brought to the expected temperature of the night air even before opening the visor. It is forbidden to open the telescope dome if the temperature difference between the outside and inside of the tower is more than 10°, since such temperature changes can lead to destruction of the mirror. Many of these problems would have been solved if the telescope had had a modern glass ceramic mirror - however, there was no money for it. Instead, we decided to remake the existing mirror.

The second problem is atmospheric conditions in the North Caucasus. Since the telescope's location is downwind of the major peaks of the Caucasus Range, turbulence significantly worsens visibility conditions (especially compared to telescopes in more favorable locations) and does not allow the full potential of the angular resolution of the reflecting telescope to be used.

For a combination of reasons, the BTA allows obtaining images with a resolution of 1.5 arcseconds only 10% of the time. For comparison, we can point out that on telescopes at the Keck Observatory, a resolution of twice that is normal.

Despite its shortcomings, the BTA was and remains an important scientific instrument, capable of seeing stars up to 26th magnitude. In tasks such as spectroscopy and speckle interferometry, where collection power is more important than resolution, BTA gives good results.

03. The Bolshoy Zelenchuk River meanders below.

05. And all around is full of meadow flowers.

08. Futuristic

09. The starry sky that we were able to see :)

14. For repair work, a gantry crane with a height of 65 meters is used

17. Nearby there are two more telescopes with mirror diameters of 1 m and 0.6 m.

18. The height of the dome is 53 meters.

20. Not far from BTA there is a town for employees to live.

21. On the way back we hit a real cloud. Later I’ll tell you how you can have a good time sleeping in Arkhyz.

More information about the CAO can be found on their official website -

June 7th, 2018

For many years, the world's largest telescope, BTA (Large Azimuth Telescope), belonged to our country, and it was designed and built entirely using domestic technologies, demonstrating the country's leadership in the field of creating optical instruments. In the early 60s, Soviet scientists received a “special task” from the government - to create a telescope larger than the Americans (Hale telescope - 5 m). It was considered that a meter more would be enough, since the Americans generally considered it pointless to create solid mirrors larger than 5 meters in size due to deformation under their own weight.

What is the history of the creation of this unique scientific object?

Now we find out...

By the way, the first photo is from a very good one, be sure to look at it too.

M. V. Keldysh, L. A. Artsimovich, I. M. Kopylov and others at the BTA construction site. 1966

The history of the Large Azimuthal Telescope (BTA, Karachay-Cherkessia) began on March 25, 1960, when, at the proposal of the USSR Academy of Sciences and the State Committee for Defense Equipment, the USSR Council of Ministers adopted a resolution on the creation of a complex with a reflecting telescope with a main mirror with a diameter of 6 meters.

Its purpose is “to study the structure, physical nature and evolution of extragalactic objects, a detailed study of the physical characteristics and chemical composition of non-stationary and magnetic stars.” The State Optical-Mechanical Plant named after. OGPU (GOMZ), on the basis of which LOMO was soon formed, and the chief designer was Bagrat Konstantinovich Ioannisiani. The BTA was the latest astronomical technology for its time, containing many truly revolutionary solutions. Since then, all large telescopes in the world have been mounted using the brilliantly proven alt-azimuth scheme, which was used for the first time in world practice by our scientists at BTA. The highest-class specialists worked on its creation, which ensured the high quality of the giant device. For more than 30 years now, BTA has been keeping its stellar watch. This telescope is capable of distinguishing astronomical objects of the 27th magnitude. Imagine the earth is flat; and then, if in Japan someone were to light a cigarette, with the help of a telescope it could be clearly seen.

Cleaning the bottom of the pit. February 1966

After analyzing all the data, the site for the BTA telescope became a place at an altitude of 2100 meters near Mount Pastukhov, not far from the village of Zelenchukskaya, which is located in Karachay-Cherkessia - Nizhny Arkhyz.

According to the project, the azimuthal type of telescope mount was chosen. The total outer diameter of the mirror was 6.05 meters with a thickness of 65 cm, uniform over the entire area.

The telescope structure was assembled in the LOMO premises. A building over 50 meters high was built especially for this purpose. Cranes with a lifting capacity of 150 and 30 tons were installed inside the hull. Before assembly began, a special foundation was made. The assembly itself began in January 1966 and lasted more than a year and a half, until September 1967.

Construction of telescope and tower foundations. April 1966

By the time the mirror blank with a diameter of 6 m was manufactured, the accumulated experience in processing large-sized optical blanks was limited. For processing a casting with a 6-meter diameter, when it was necessary to remove about 25 tons of glass from the workpiece, the existing experience turned out to be unsuitable, both due to low labor productivity and because of the real danger of the workpiece failure. Therefore, when processing a workpiece with a diameter of 6 m, it was decided to use a diamond tool.

Many of the telescope's components are unique for its time, such as the main spectrograph of the telescope, which has a diameter of 2 meters, a guiding system, which includes a guide telescope and a complex photo and television system, as well as a specialized computer for controlling the operation of the system

Summer 1968 Delivery of telescope parts

BTA is a world-class telescope. The large light-gathering ability of the telescope makes it possible to study the structure, physical nature and evolution of extragalactic objects, a detailed study of the physical characteristics and chemical composition of peculiar, non-stationary and magnetic stars, study of the processes of star formation and evolution of stars, study of the surfaces and chemical composition of the atmospheres of planets, trajectory measurements of artificial celestial bodies at great distances from the Earth and much more.

With its help, numerous unique studies of outer space were carried out: the most distant galaxies ever observed from Earth were studied, the mass of the local volume of the Universe was estimated, and many other mysteries of space were solved. St. Petersburg scientist Dmitry Vyshelovich, with the help of the BTA, sought an answer to the question of whether fundamental constants drift in the Universe. Based on the results of his observations, he made the most important discoveries. Astronomers from all over the world are lining up to make observations using the famous Russian telescope. Thanks to the BTA, domestic telescope builders and scientists have accumulated vast experience, which has made it possible to open the way to new technologies for studying the Universe.

Installation of dome metal structures. 1968

The resolving power of the telescope is 2000 times greater than the resolution of the human eye, and its radius of “vision” is 1.5 times greater than that of the largest US telescope at that time at Mount Palomar (8-9 billion light years versus 5-6, respectively ). It is no coincidence that BTA is called the “Eye of the Planet”. Its dimensions are amazing: height – 42 meters, weight – 850 tons. Thanks to the special design of the hydraulic supports, the telescope seems to “float” on a thin oil cushion 0.1 mm thick, and a person is able to rotate it around its axis without the use of equipment or additional tools.

By Government Decree of March 25, 1960, the Lytkarino Optical Glass Plant was approved as the lead contractor for the development of a technological process for casting a mirror blank with a diameter of 6 m from glass and for the production of a mirror blank. Two new production buildings were built especially for this project. It was necessary to cast a glass blank weighing 70 tons, anneal it and carry out complex processing of all surfaces with the production of 60 mounting blind holes on the back side, a central hole, etc. Three years after the Government Decree was issued, a pilot production workshop was created. The workshop's tasks included installation and debugging of equipment, development of an industrial technical process and production of a mirror blank.

A set of search works carried out by LZOS specialists to create optimal processing modes made it possible to develop and implement a technology for manufacturing an industrial blank for the main mirror. Processing of the workpiece was carried out for almost a year and a half. To process mirrors, the Kolomna Heavy Machine Tool Plant created a special rotary machine KU-158 in 1963. In parallel, extensive research work was carried out on the technology and control of this unique mirror. In June 1974, the mirror was ready for certification, which was successfully completed. In June 1974, the crucial stage of transporting the mirror to the observatory began. On December 30, 1975, the act of the State Interdepartmental Commission on the acceptance into operation of the Large Azimuth Telescope was approved.

1989 Assembly of the 1-meter Zeiss-1000 telescope

Transportation of the upper part of the BTA pipe. August 1970

Today there are new, more efficient astronomical systems with larger, including segmented, mirrors. But in terms of its parameters, our telescope is still considered one of the best in the world, which is why it is still in high demand among domestic and foreign scientists. Over the past years, it has undergone repeated modernization, primarily improving the management system. Today, observations can be made using a fiber-optic connection directly from the astronomer town located in the valley.

The Soviet optical industry of those times was not designed to solve such problems, so to create a 6-meter mirror, a plant was specially built in Lytkarino near Moscow on the basis of a small workshop for the production of mirror reflectors.

The blank for such a mirror weighs 70 tons, the first few were “screwed up” due to haste, since in order not to crack they had to cool for a very long time. The “successful” billet cooled for 2 years and 19 days. Then, during its polishing, 15,000 carats of diamond tools were produced and almost 30 tons of glass were “erased.” The fully finished mirror began to weigh 42 tons.

The delivery of the mirror to the Caucasus is worth a special mention.. First, a dummy of the same size and weight was sent to its destination, some adjustments were made to the route - 2 new river ports were built, 4 new bridges and 6 existing ones were strengthened and expanded, several hundred kilometers were laid new roads with perfect surface.

The mechanical parts of the telescope were created at the Leningrad Optical-Mechanical Plant. The total mass of the telescope was 850 tons.

But despite all efforts, it was not possible to “outdo” the American Hale telescope BTA-6 in quality (that is, in resolution). Partly due to defects in the main mirror (the first pancake is still lumpy), partly due to the worst climatic conditions at its location.

The installation of a new, third mirror in 1978 significantly improved the situation, but the weather conditions remained the same. In addition, the work is complicated by the too high sensitivity of the solid mirror to minor temperature fluctuations. “Does not see” - this is, of course, said loudly; until 1993, BTA-6 remained the world’s largest telescope, and it remains the largest in Eurasia to this day. With the new mirror, it was possible to achieve a resolution almost like that of the Hale, and the “penetrating power,” that is, the ability to see faint objects, is even greater in the BTA-6 (after all, the diameter is a whole meter larger).

Over the 30-year period of operation of the telescope, its mirror was recoated several times, which led to significant damage to the surface layer, its corrosion, and, as a result, up to 70% of the reflective ability of the mirror was lost. And yet, the BTA was and remains a unique tool for astronomers, both Russian and foreign. But to maintain its performance and increase efficiency, it became necessary to reconstruct and update the main mirror. Currently, the technology of shaping and unloading the mirror, which is owned by the specialists of JSC LZOS, makes it possible to triple its optical characteristics, including angular resolution.

Today, the technological process of shaping the surfaces of astronomical optical parts at the Lytkarino Optical Glass Plant has been brought to a new level, the achieved quality of surface shape deviations from the theoretical has increased by an order of magnitude due to automation and modernization of production and computer control. Both the mechanical base and the technology for lightening and unloading mirrors using modern computer equipment have improved significantly. The machines for milling, grinding and polishing the 6-meter mirror have also been modernized in accordance with modern requirements. Optical controls have also been significantly improved.

The main mirror was delivered to the Lytkarino Optical Glass Plant. The milling stage has now been completed. The top layer about 8 mm thick was removed from the working surface. The mirror is transported into a heat-stabilized case and installed on an automated machine for grinding and polishing the working surface. According to the technical director - chief engineer of the enterprise S.P. Belousov, this will be the most difficult and critical stage of mirror processing - it is necessary to obtain a surface shape with much smaller deviations from the ideal paraboloid than was achieved in the seventies. After this, the telescope mirror, with its resolution and penetrating power improved by an order of magnitude, will be able to serve Russian and world science for at least another 30 years.