Observatory Large Azimuth Telescope (LTA). BTA - Large Azimuth Telescope
BTA dome
BTA ("large azimuthal telescope") is the largest optical telescope in Eurasia with a main monolithic mirror diameter of 6 m. It is installed at the Special Astrophysical Observatory.
It was the largest telescope in the world from 1975, when it surpassed the 5-meter Hale telescope of the Palomar Observatory, until 1993, when it started operating 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 in terms of mass, and the BTA dome is the largest astronomical dome in the world.
Device
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 without frame is 42 tons. The optical scheme of the BTA provides for operation in the main focus of the primary mirror and two Nesmith foci. In both cases, an aberration corrector can be applied.
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 the telescope has a significant thermal 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 dome space ventilation system. Cooling units are currently installed in the tower, designed, if necessary, to artificially lower the temperature of the main mirror of the telescope in accordance with the current weather forecast.
The reflective coating of the mirror is made of unprotected aluminum 100 nanometers thick. The technology of aluminizing the main mirror of the telescope, developed by the manufacturer, provided for the replacement of the working aluminum layer every 3-5 years. By improving the components of the mirror aluminizing vacuum unit (VUAZ-6), the service life of the mirror layer was increased to an average of 10 years. Last time the aluminum layer of the main mirror of the BTA was changed in July 2015.
Modernization
On May 11, 2007, the transportation of the first BTA main mirror to the LZOS, which manufactured it, began for the purpose of deep modernization. The second primary mirror is now installed on the telescope. After processing in Lytkarino - removing 8 millimeters of glass from the surface and repolishing, the telescope should enter the top ten most accurate in the world. The CAO expected that the updated mirror, after a 5 million euro repair, 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, Zelenchuksky district of the 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 cm refractor telescope became the largest in the world at the time. Due to the peculiarities of the tasks of the Pulkovo observatory (in particular, the exact time), it did not need large reflectors. In 1926, a 1-meter English reflector was installed at the Simeiz Observatory on Mount Koshka.
In 1961, the ZTSh-2.6 telescope manufactured at the State Optical and Mechanical Plant, with a mirror diameter of 2.6 meters, was launched at the Crimean Astrophysical Observatory, the largest telescope in the USSR and Europe. By that time, scientists had developed a 5-meter telescope and thought about a 6-meter one, and the RATAN-600 radio telescope was also on the way. It was decided to put both instruments side by side, so a new place for the observatory was required. good places located in the Central Asian republics former USSR, however, a political decision was made to place the instrument in the RSFSR.
A. N. Kosygin officially announced the decision of the USSR Government to create a 6-meter telescope in the country 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 6 meters in diameter. The main work was entrusted to the Leningrad Optical and Mechanical Plant, the Lytkarinsky Optical Glass Plant (LZOS), 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 executor for the development of a technological process for casting a mirror blank with a diameter of 6 m and for the manufacture 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 manufacture of a central through hole and more than 60 landing blind holes on the back side.
During three years A special building of the pilot production workshop for the manufacture of BTA blanks was designed and built, the task of which included the installation and debugging of equipment, the development of an industrial process and the manufacture of a mirror blank. The main equipment of the workshop was unique and unparalleled.
LZOS and GOI specialists 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 the GOI, according to which a trial production and experimental casting of a workpiece with a diameter of 6200 mm was made. On this experimental blank, all modes and methods of operation, as well as the organization of the ebb, were worked out. A technological process was drawn up for casting a regular billet.
In November 1964, the first billet of the main mirror was cast, which was annealed, that is, slowly cooled at a given regime, for more than 2 years. To process this blank, it was necessary to remove about 25 tons of glass. The existing experience in processing large-sized workpieces turned out to be unsuitable, it was decided to use diamond equipment, 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. The processing of the workpiece was carried out for almost a year and a half on a special carousel 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 were used in powder form. To remove the allowance of 28 tons, grinding and polishing the side surface, 7000 carats of diamonds were used. The marking and processing of 66 blind holes to accommodate the mechanisms for unloading the mirror was difficult. The mass of the blank, calculated according to the actual dimensions, was about 42 tons. The blank 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 the 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 plant for aluminizing the primary mirror was delivered.
In June 1974, the transportation of the mirror began. After manufacturing, it was preserved with a special protective film and installed in a special shipping container. In view of its exceptional value, extraordinary precautions were taken in 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 the transportation of the mirror were developed. Trailers with a container and a frame were installed on a barge, secured and with the help of a powerful tugboat delivered through the Moscow-Volga canal, along the Volga and the Volga-Don canal to Rostov-on-Don. Then the trailers took him down the roads 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 in September-October it was mounted in a frame. 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, an act of the State Interdepartmental Commission for the Acceptance of the Bolshoi azimuth telescope and the telescope was put into operation.
Later, a second mirror was manufactured and delivered in August 1978; in 1979 it was aluminized and installed on the telescope.
Problems
As with other large telescopes, thermal deformation of the main mirror is a big problem. In BTA, this problem is especially pronounced 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 a factor of one and a half. To increase the duration of the observation time, the temperature of the telescope room is controlled by the air conditioning system, and is brought to the expected temperature of the night air even before the visor is opened. It is forbidden to open the dome of the telescope when the temperature difference between outside and inside the tower is more than 10°, as such temperature changes can lead to the destruction of the mirror. Many of these problems would have been solved if the telescope had a modern glass-ceramic mirror - however, there was no money for it. Instead, they decided to remake the existing mirror.
The second problem is atmospheric conditions in the North Caucasus. Since the location of the telescope is located downwind from the large peaks of the Caucasus Range, turbulence significantly worsens the visibility conditions (especially compared to telescopes in more favorable places) and does not allow using the full potential of the angular resolution of the mirror telescope.
For a combination of reasons, the BTA makes it possible to obtain images with a resolution of 1.5 arcseconds only for 10% of the time. For comparison, it can be pointed out that twice the resolution of the Keck Observatory telescopes is common.
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 the collecting power is more important than the resolution, the BTA gives good results.
The BTA telescope is the largest optical telescope in Eurasia, the largest telescope in Russia. The full name and decoding of the abbreviation sounds like this - B big T telescope BUT lt-azimuth.
The mirror diameter is 6 meters.
Installed at the foot of Mount Pastukhov at an altitude of 2070 m above sea level. Karachay-Cherkessia. Works since 1966.
Back in 1975, the telescope was considered the largest in the world, surpassing in its parameters and technical capabilities the Hale telescope at the Palomar Observatory (California). But in 1993, the palm, so to speak, was selected 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, with such funds invested in the project (more than $ 70 million), by astronomical standards, it turned out to be a real giant in scientific research space.
The question is, why did Russia allow the Americans (or as soon as 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 world, while projects of the post-Soviet era are just gaining momentum, rising from their knees? Luckily they go up. However, I don’t remember that there were as many charitable foundations or charitable patrons in Rosnauka as there are in the states. But, they could have shocked some bunch of oligarchs with their billions ... The amounts are not so hot, which are prohibitive, given the luxurious villas and yachts, islands and other senseless investments of some of the Russian representatives " powers of the world this"...
By the way, in 1985 the Americans raised funds for the work charitable foundation William Myron Keck, who, in fact, financed the entire project with a solid 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 here's what they got:
Nevertheless, returning to our telescope, the BTA remained the telescope with the world's largest monolithic mirror until 1998. But the most curious information included in the list of awesome cool ones 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.
To understand me correctly - there are no goals and objectives to admire alone, but pour pseudo-mud on your own ... No! I would like it to be like a human being, so that they invest more in science than in weapons, more than in “priority” dismantling with pipes from Gazprom, figuring out which stream is better - northern, southern or some other ... I would like to invest more than other states. And, perhaps, scientists will not leave 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 assignee of the USSR. What would we like to know about him? I tried to find and compress the information to a more or less digestible, and interesting.
1. LYTKARIN OPTICAL GLASS
There are only five countries in the world that can produce the entire range of optical glass: Russia, Germany, China, the USA and Japan. Lytkarinsky plant is known primarily for its large-sized optics. Its mirrors are installed on the largest telescopes around the world. One of these factory mirrors 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. Given 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 should have been changed to an updated one - weighing 75 tons, but I did not find any 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 azimuth telescope. According to technology, such a mirror after smelting should cool down for a year and a half. 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 CEO Shvabe Holding - Sergey Maksin at the Oboronexpo international exhibition.
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 in azimuth. Hence the name - B big T telescope BUT lt-azimuth.
AT Soviet time, in addition to a huge staff of several hundred people, the work of the telescope was also monitored by a huge large-sized computer, which now stands in the museum of the observatory. Over time, the sensors, the control system was modernized, but the mechanics remained. Soviet technologies are not khukhr-mukhr for you ... They did it for centuries.
3. Staff
According to astronomer Alexei Moiseev, about 400 people are currently working at the observatory.
“... we have one of the highest percentages of non-scientific staff among institutions Russian Academy Sciences - engineers, technicians. We have two main telescopes: the six-meter BTA and the Ratan-600 radio telescope. We need people to serve them. Our downtime of telescopes for technical reasons is measured by only hours a year - this is very little.
By the way, an academic campus was built not far from the observatory, where about 1,200 people live today - scientists with their families. Despite protests against the construction of the town by the first director of the observatory, Ivan Kopylov, it was decided to build it. And the protest was as follows - astronomers are not geologists, you do not need to force them to work on a rotational basis.
Today one of the most big problems campus - medical care. As it turned out, as a result of the RAS reform in 2015, federal agency scientific organizations refuse to support the local dispensary, and the nearest hospital is 30 km away by a mountain road. The question is, are you crazy? On the one hand, you raise questions - why is there such a big brain drain, on the other hand - you yourself push it out of the country with 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. On enthusiasm and stupid reforms, the country will not move to a new level ...
In conclusion, I recommend browsing with a large number of high-quality images about the BTA telescope. I also recommend watching a short video from the Roscosmos TV Studio. In the same place - on the Roscosmos channel, a lot interesting videos reviews - for the most inquisitive. In the meantime, here are some short facts about the BTA telescope:
Telescope BTA (Russia) - description, history, location. Exact address, phone number, website. Reviews of tourists, photos and videos.
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The Arkhyz observatory, the largest in the country, was opened in 1966. Its main object, the BTA telescope (large azimuthal telescope), stands on the slope of Mount Pastukhov, at an altitude of more than 2 km. At the time of installation, it was included in the Guinness Book of Records as the largest in the world, and now it occupies the first place in Eurasia in terms of size. Two more smaller telescopes are installed nearby, with mirror diameters of 1 and 0.6 m. Observations are made every night if there are no clouds.
Glass with a diameter of 6 m and a thickness of 0.8 m was cast and cooled for two years under special conditions so that there were no small bubbles inside that affected the clarity of the image. Then it was polished with diamonds, the desired degree of curvature was achieved, and aluminum was sprayed. As a result, the thickness of the glass was halved.
During the tour, the guide talks about the features of the telescope, what it is used for, why it is installed here. Other parts of the observatory will also be shown. There is a hall where they broadcast a film about space and the universe, a souvenir shop. And it will be nice to just walk around the territory - magnificent views open up around. At the observatory there is a small hotel where scientists live. By agreeing with the administration, you can stay overnight and take part in observations of space bodies.
Practical Information
Address: Nizhny Arkhyz, Special Astrophysical Observatory. Coordinates: 43.6432, 41.4542. Web site .
On the way from Zelenchukskaya to Arkhyz, the dome is visible from the road, 10 km of mountain serpentine lead to it. A barrier blocks the entrance, during the day it rises and lets visitors through. Then there is an asphalt road, along which there are observation platforms with mountain views.
The observatory is open to tourists only on weekends from 9:00 to 15:00. The price of an adult ticket is 120 RUB, a child ticket is 80 RUB. Tours last 40 minutes, they are conducted for groups of 10 people. Prices on the page are for February 2017.
BTA(“large azimuthal telescope”) is the largest optical telescope in Eurasia with a main monolithic mirror diameter of 6 . Installed at the Special Astrophysical Observatory.
It was the largest telescope in the world from 1975, when it surpassed the 5-meter Hale telescope of the Palomar Observatory, and until 1993, when the Keck telescope with a 10-meter segmented mirror was launched. Nevertheless, the BTA remained the telescope with the world's largest monolithic mirror until the commissioning of the VLT telescope (diameter 8.2 m) in 1998. To this day, the BTA mirror is the largest in the world in terms of mass, and the BTA dome is the largest astronomical dome in the world.
Encyclopedic YouTube
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✪ Astrotourists on BTA
✪ The mirror has been updated in the Large Azimuth Telescope
Subtitles
Device
Chief Designer - Doctor of Technical Sciences Bagrat Konstantinovich Ioannisiani (LOMO) .
The main mirror of the telescope has a significant thermal 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 dome space ventilation system. Cooling units are currently installed in the tower, designed, if necessary, to artificially lower the temperature of the main mirror of the telescope in accordance with the current weather forecast.
The reflective coating of the mirror is made of unprotected aluminum with a thickness of 1 micron. The aluminizing technology of the main telescope mirror, developed by the manufacturer, provided for the replacement of the working aluminum layer every 3-5 years. By improving the components of the mirror aluminizing vacuum 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 main mirror of the 6-m telescope was changed in July 2005.
Modernization
On May 11, 2007, the transportation of the first BTA main mirror to the LZOS, which manufactured it, began for the purpose of deep modernization. The second primary mirror is now installed on the telescope. 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. The CAO expected that the updated mirror, after a 5 million euro repair, would return to the observatory in mid-2013 [ ] . In 2015, it is planned to install a new 75 ton mirror manufactured at the Lytkarino Optical Glass Plant.
Location
In 1961, the ZTSh-2.6 telescope manufactured at the State Optical and Mechanical Plant, with a mirror diameter of 2.6 meters, was put into operation at the Crimean Astrophysical Observatory - the largest telescope in the USSR and Europe. By that time, scientists who?] developed a 5-meter telescope and thought about a 6-meter one, and the RATAN-600 radio telescope was on the way. It was decided to put both instruments side by side, so a new place for the observatory was required. Good places are in the Central Asian republics of the former USSR, but a political decision was made to place the instrument in the RSFSR. [ ]
A. N. Kosygin officially announced the decision of the USSR Government to create a 6-meter telescope in the country 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 6 meters in diameter. The main work was entrusted to the Leningrad Optical and Mechanical Plant, Lytkarinsky Optical Glass Plant (LZOS), as well as a number of other enterprises.
The Lytkarino Optical Glass Plant was approved as the main executor for the development of a technological process for casting a mirror blank with a diameter of 6 m and for the manufacture 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 manufacture of a central through hole and more than 60 landing blind holes on the back side.
Within three years, a special building of the pilot production shop for the manufacture of BTA blanks was designed and built, the task of which included the installation and debugging of equipment, the development of an industrial technical process and the manufacture of a mirror blank. The main equipment of the workshop was unique and unparalleled.
LZOS and GOI specialists 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 the GOI, according to which a trial production and experimental casting of a workpiece with a diameter of 6200 mm was made. On this experimental blank, all modes and methods of operation, as well as the organization of the ebb, were worked out. A technological process was drawn up for casting a regular billet.
In November 1964, the first billet of the main mirror was cast, which was annealed, that is, slowly cooled at a given regime, for more than 2 years. To process this blank, it was necessary to remove about 25 tons of glass. The existing experience in processing large-sized workpieces turned out to be unsuitable, it was decided to use diamond equipment, 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. The processing of the workpiece was carried out for almost a year and a half on a special carousel 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 were used in powder form. To remove the allowance of 28 tons, grinding and polishing the side surface, 7000 carats of diamonds were used. The marking and processing of 66 blind holes to accommodate the mechanisms for unloading the mirror was difficult. The mass of the blank, calculated according to the actual dimensions, was about 42 tons. The blank 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 the 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 plant for aluminizing the primary mirror was delivered.
In June 1974, the transportation of the mirror began. After manufacturing, it was preserved with a special protective film and installed in a special shipping container. In view of its exceptional value, extraordinary precautions were taken in 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 the transportation of the mirror were developed. Trailers with a container and a frame were installed on a barge, secured and with the help of a powerful tugboat delivered through the Moscow-Volga canal, along the Volga and the Volga-Don canal to Rostov-on-Don. Then the trailers delivered him 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 in September-October it was mounted in a frame. After trial operation during the winter of 1974/75 and 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.
Later, a second mirror was manufactured and delivered in August 1978; in 1979 it was aluminized and installed on the telescope.
Problems
As with other large telescopes, thermal deformation of the main mirror is a big problem. In BTA, this problem is especially pronounced 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 a factor of one and a half. To increase the duration of the observation time, the temperature of the telescope room is controlled by the air conditioning system, and is brought to the expected temperature of the night air even before the visor is opened. It is forbidden to open the dome of the telescope when the temperature difference between outside and inside the tower is more than 10°, as such temperature changes can lead to the destruction of the mirror. Many of these problems would have been solved if the telescope had a modern glass-ceramic mirror - however, there was no money for it. Instead, we decided to remake the existing mirror (see below).
The second problem is the atmospheric conditions in the North Caucasus. Since the location of the telescope is located downwind from the large peaks of the Caucasus Range, atmospheric turbulence significantly worsens the visibility conditions (especially compared to telescopes in more favorable places) and does not allow using the full potential of the angular resolution of the mirror telescope.
For a combination of reasons, the BTA makes it possible to obtain images with a resolution of 1.5 arc seconds only for 10% of the time. For comparison, it can be pointed out that twice the resolution of the Keck Observatory telescopes is common.
Despite its shortcomings, the BTA was and remains an important scientific instrument, capable of seeing stars up to magnitude 26. In tasks such as spectroscopy and speckle interferometry, where collecting power is more important than resolution, BTA gives good results.
Gallery
This New Year I wanted to spend time in nature and try something new. Then I came across an announcement from the Intellect tour about two New Year's tours: "New Year under the stars of Arkhyz" and "New Year in Murmansk". Since the auroras are numerous in the past year, the choice was made in favor of mountains, telescopes and astrophotography.
After spending almost two days on the road, we got from Yaroslavl to the upper platform of the Special Astrophysical Observatory of the Russian Academy of Sciences located in the North Caucasus at the foot of Mount Pastukhov in the Zelenchuksky district of the Karachay-Cherkess Republic. The BTA (Large Alt-Azimuth Telescope) is located here - the largest optical telescope in Eurasia with a main monolithic mirror diameter of 6 m. In today's post, we will talk about the BTA and its closest neighbors.
01. We settled in the wonderful hotel "Andromeda" (a building with balconies, lined with yellow stone), located at an altitude of 2000 meters (above sea level) on one of the spurs of Mount Pastukhov. From the village of Nizhny Arkhyz, a winding mountain road 17 km long and with a height difference of about 1000 meters leads here. With a vigorous rise in the car, the ears are slightly pawned, yes.
Three white domes to the left of the hotel - Arkhyz (formerly Kosmoten) optical observation station for artificial earth satellites. On clear nights, a "laser show" is arranged here with the help of a Sazhen-TM laser locator. The station is equipped with Zeiss-600 M and ATT-600 optical telescopes, and since 2014 with a unique multichannel monitoring telescope (MMT). Now the main task of the station is to track space debris, it can also track satellites, meteor activity and meteoroids. However, with the commissioning of the MMT, the station can study moving objects inside our galaxy and beyond, thereby helping fundamental astrophysics.
In the distance, on the top of Mount Chapal, one can see the optical part of the Krona space object recognition complex, and below and a few kilometers to the right of the top, the radar part. This is an object of the Russian Aerospace Defense Forces. "Krona" recognizes space objects, reveals their belonging, purpose and specifications. The capacity of the complex is 30,000 space objects per day.
Principle of operation: The laser-optical locator on the top of Mount Chapal consists of several channels. The receiving channel is an optical telescope with a highly directional hood, which allows you to obtain images of space objects in reflected sunlight at a distance of up to 40,000 km, is controlled according to a predetermined program and accompanies pre-selected objects. Passive channel for autonomous detection of space objects - automatically conducts patrol observations in order to detect previously unknown space objects in its area of \u200b\u200bthe celestial sphere, determines their characteristics and transmits all this to the Space Control Center. The disadvantage of the above two channels is that they process the reflected from the object sunlight and can only work at night and only when there is no cloud cover. Receiving-transmitting channel - emits a laser beam towards a space object, receives and processes the reflected signal. Doesn't depend on the time of day. The radar station is located a few kilometers from the top of Mount Chapal. Its coverage area is the upper hemisphere with a radius of 3500 km. Consists of two channels operating in different ranges. Decimeter range - channel "A" - a receiving-transmitting phased antenna array with an aperture of 20 × 20 m. Before the collapse of the USSR, the Krona complex used 3 MiG-31D interceptor fighters armed with 79M6 Kontakt missiles (with a kinetic warhead) to destroy enemy satellites in orbit. After the collapse of the USSR, MiG-31D fighters went to Kazakhstan. It is planned that the Space Forces will use Russian MiG-31s. The Fakel design bureau is developing a replacement for the 79M6 Kontakt missiles.
The complex has been developed since 1974, in 1994 it was put on experimental combat duty, and in 1999 it entered combat duty.
Centimeter range - channel "H" - a receiving-transmitting system consisting of five rotating parabolic antennas that operate on the principle of an interferometer, due to which it very accurately measures the parameters of the orbit of a space object.
02. From the site near the hotel there is a beautiful view of the giant BTA (mirror diameter 6 m) and Zeiss-1000 (mirror diameter 1 m). BTA is located at an altitude of 2070 meters and an aluminum dome with a diameter of 45 meters rushes up another 53 meters. Behind the dome is a huge crane used to build the dome, mount and maintain the telescope. Vertical design under the tap - "cobra", used for repair work on the dome of the telescope.
BTA stands for Large Alt-Azimuth Telescope. Sometimes it is called the "Arkhyz" telescope, but, as we can see, there are many telescopes (even optical ones) in the Nizhny Arkhyz region :) I will talk about the RTF-32 and RATAN-600 radio telescopes separately.
Both telescopes belong to the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS), which is currently the largest Russian astronomical center for ground-based observations of the Universe.
03. 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 of the Keck Observatory was launched. However, the BTA remained the telescope with the world's largest monolithic mirror until 1998. To this day, the BTA dome is the largest astronomical dome in the world. The visor, weighing 32 tons, fully opens in 25 minutes, leaving an opening 11 meters wide in the dome.
04. We go inside, on an excursion. On the ceiling is a mosaic pano with the zodiac constellations. A sad joke in a cloudy sky - "these are the only stars you can see today." We weren't very lucky with the weather :(
05. The tour is conducted by the employees of the observatory, people who are sincerely passionate about their work and very positive. I don’t know the name of our guide, but I also remember him for the fact that he gave a couple useful tips tourist plan (about local "cafes" and honey merchants) and ended the tour with interesting philosophical remarks about life in general. It seems to me that the employees here comprehend Zen no worse than Tibetan monks! ;)
06. So, the telescope itself. It 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. The lower circular platform, which you see in the photo, can rotate around its axis, I will describe how this is technically organized below. On the platform there is a "fork" of two four-story columns (they contain various equipment, in particular, the right column is entirely occupied by the Main Stellar Spectrograph). The columns support the forty-meter "tube" of the telescope. In the photo, we just see the back of the main mirror with unloading mechanisms. The weight of the mirror is so great that with any movement, it changes its shape, deforms, and bends. To prevent loss of shape, 66 blind holes are drilled from the underside of the mirror. They have special lever mechanisms for unloading, which, as it were, support each part of the mirror from the inside. They work at any tilt of the mirror and prevent its distortion.
07. BTA is a reflecting telescope. The main mirror (covered with white lamellae, as it is daytime and no observations are being made) 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. In order for the mirror to better reflect light, a very thin layer of aluminum is sprayed onto it in a vacuum. This procedure must be repeated every few years.
A parabolic mirror was manufactured at the Lytkarino Optical Glass Plant in 1963-1974. In a specially built regenerative bath furnace at a strictly defined temperature of 1600 degrees, the process of melting glass and casting a blank was going on for almost 2 years (until November 20, 1964). The billet also cooled for more than 2 years (736 days, until December 5, 1966), which made it possible to avoid the occurrence of microcracks. Then the laborious process of its processing began. Its weight was 70 tons. Preliminary processing was carried out by the Lytkarinsky plant, after which the best one was chosen from the 2 available blanks. On September 4, 1970, the blank was accepted by a special commission headed by Academician L.A. Artsimovich. The final grinding and polishing of the mirror was carried out by a team of highly qualified LOMO opticians under the guidance of G.I. Cupid. For this, a special machine was created, built at the Kolomna Heavy Machine Tool Plant. In June 1974, the mirror was ready for certification. On July 10, an interdepartmental commission chaired by Academician A.M. Prokhorov received a mirror for its subsequent installation on a telescope.
By the time the mirror was accepted by the interdepartmental commission, near the village of Zelenchukskaya on the spur of Mount Pastukhov at an altitude of 2110 m above sea level, a tower was already rising to accommodate the telescope and the assembly of a huge instrument was in full swing. The Special Astrophysical Observatory (SAO) was founded here. The tower was also built taking into account a number of special conditions - compliance with the strictest thermostatic regime, creating an optimal building shape from the point of view of aerodynamics and protecting the under-dome space from direct sun rays and atmospheric precipitation.
The assembly of the telescope took 4 years (1970-1974). In the summer of seventy-four, the main mirror set off on a journey lasting almost 2 months - first on barges on water, then on land, including along a specially built mountain road. On November 3, the telescope was put into trial operation, and a year later, on December 30, 1975, the BTA was accepted by the State Interdepartmental Commission with an "excellent" rating. Thus, it took 15 years to make a giant telescope. This is relatively little - the United States has been creating its device with a 5-meter mirror for 22 years.
08. The light from the mirror is collected, concentrated and reflected into the upper part of the telescope, where the primary receiver (black "glass") is located. The focal length of the telescope as a result is 24 meters. But if you use an additional mirror that throws light back, and then into one of the side focuses, then the focal length increases to 180 meters.
By the way, earlier an astronomer was sitting in the "glass", performing observations and fixing the image on photographic plates. Now, instead of a person, there is electronics. And this is also good because the temperature inside the dome is stabilized by the ventilation and air conditioning system and is brought to the expected temperature of the night air even before the visor opens. That is, if outside - 15, then inside it will be - 15. No heaters, because. this will instantly distort the resulting image.
On the perimeter of the dome, air conditioning and ventilation systems are just visible. Downstairs behind the glass windows is the old control room. Now it is not used and from the inside it looks like warm and lamp, evoking associations with Star Trek. I can’t insert a photo of the remote control with buttons now. Modern control is carried out from a single computer.
09. After examining the "tip of the iceberg", we were taken to the lower floors and shown the mechanisms that ensure the rotation of the telescope. The telescope is mounted on a turntable with a nine-meter vertical axis. Top part platforms - a circle with a diameter of 12 meters (in the pictures above), goes into a spherical ring, which acts as a bearing. The spherical ring rests on fluid friction bearings, three rigid and three spring-loaded.
10. Due to the special design of the hydraulic supports, the BTA seems to “float” on the thinnest oil cushion 0.1 mm thick, and a person is able to turn it around its axis. The turntable platform also houses the column lift motors and the oil pipelines of the telescope's tilt systems. The rotation of the "pipe" of the telescope along the horizontal axis, its inclination, is provided in the same way.
11. The oil station room - the telescope's oil supply system, one might say, is the heart of the whole structure. The main and standby pumps pump oil into the channels of the cushions under a pressure of about 70 atmospheres. (Yes, this is a basin. With oil. No, I didn’t see blue electrical tape.)
12. A floor below is a rotation drive. These are two wheels for tracking objects in two planes at once. A unique high-precision worm gear with a diameter of almost 6 meters ensures the movement of the moving part of the telescope with an accuracy of tenths of a second of arc.
13. Upgraded digital motor controllers ensure high accuracy. And once there was analog equipment.
14. Even lower - the lower block of bearings that fix the axis - the "heel" of the telescope. However, the whole structure does not stand on it, no. "Heel" orients it vertically. The foundation of the telescope is separated from the general foundation of the tower in order to avoid unnecessary vibrations.
15. The next day the weather became even "cooler", but it became possible to walk around, enjoy the snow and take some atmospheric photos.
BTA, crane and "cobra" and a man to assess the scale.
16. Given that there was no snow in Yaroslavl at that moment, and in Rostov-on-Don the grass was green in places, everyone was very happy with the snow. Moreover, the snowfall should be replaced by a clear sky and it will be possible to work out astrophotography. View of the BTA dome from the beginning of the stairs.
17. Frost and sun! Went to Star Hill. From there too beautiful view to the observatory. The medium-sized building with a dome to the right of the BTA is the Zeiss-1000 telescope, what do the small domes to the right of it hide, I don’t know, maybe the Zeiss-600 telescope or some other?
18. By the way, the telescope is afraid of clouds. At this height, the clouds float at the level of the tower. If suddenly a cloud peeps into the open visor of the dome, it will be bad - everything will instantly become wet: the dome, the structure of the telescope, instruments, and most importantly, the main mirror. The telescope will fail for a long time, and this cannot be allowed to happen. Since the cloud cannot be stopped and the 32-ton visor of the tower cannot be quickly closed, astronomers are waiting for the cloudiness at the telescope levels to completely dissipate.
19. The sky is clearing up, but there are still too many clouds, so BTA is "sleeping". Orion also covered himself slightly with a "blanket".
20. Finally, a clear night came out. The visor is open, the light inside is off: there are observations!
30. The picture is spectacular due to the illumination inside the dome, but observations are not being made at this moment, some technical work is being done, adjustments are taking place.
BTA is a world-class telescope. The large light gathering capacity of the telescope makes it possible to study the structure, physical nature and evolution of extragalactic objects, a detailed study of physical characteristics and chemical composition peculiar, non-stationary and magnetic stars, the study of star formation and evolution of stars, the study of the surfaces and chemical composition of planetary atmospheres, 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. Petersburg scientist Dmitry Vyshelovich, using the BTA, was looking for an answer to the question of whether the fundamental constants drift in the Universe. As a result of observations, he made the most important discoveries. Thanks to the BTA, domestic telescope builders and scientists have accumulated vast experience, which made it possible to open the way to new technologies for studying the Universe.
31. I am very glad that I was able to see the BTA with my own eyes, I am glad that this creation of engineering thought of its time is still in service, being modernized and developing. Even if there were failures on the life path of the telescope, even if the telescope itself was born from the controversial idea of "catching up and overtaking America", even though more powerful instruments have appeared now, this does not in the least detract from its significance and uniqueness, the work of all the people who participated in its creation and worked on it. There is something meditative about sitting on a bench in front of the BTA dome, looking at it, at the mountains around, at the sky, listening to the noise of its mechanisms against the background of ringing silence...
At the end of the post, old documentary on the construction and principles of operation of the BTA.
