The Copernicus telescope
It was prof. Leonida Rosino who, at the end of the '60, had the idea of building a new telescope of larger size than the historical Galileo one, the 122 cm. The extension of the research field was widening to even more distant and feeble astronomical objects. Therefore it was necessary to use a more powerful tool that would keep the Asiago Observatory in line with the major European Astronomical Institutes. Already at that time the urban expansion of Asiago had begun to greatly damage the observations and the choice of the location for the new instrument was, consequently, a decision much debated.
To avoid the intrusion of night street lighting on the results of observations it was necessary to move as far away as possible from the residential area of the Plateau. On the other hand, the project for a new telescope required a considerable financial commitment, at a time of economic straits, especially for the scientific research.
The choice of the site where to place the new telescope had to balance the advantage of already having available in Asiago offices, homes for astronomer and equipped workshops, with the disadvatage of a growing country due to increasing tourism and unscrupulous real estate speculation which caused the worsening of the night sky. The years of the construction of the 122 cm telescope were so far away, years when the Prefect’s Commissioner of Asiago, Mr. Cunico, in his inaugural speech, praised the wonderful clearness of the skies of Asiago.
The decision to take was really important and prof. Rosino in the summer of 1969 met all the astronomers in Asiago to listen to their different opinions and share with his collegues a very important choice. It was decided to place the new instrument to Cima Ekar, at an altitude of 1370 meters, in a place at about 5 km as the crow flies from Asiago and therefore away from the bright lights of the village, but at the same time easy to reach from the main office at Pennar. The financial difficulties weighed on this choice. It was in this way that the project of building the 182 cm telescope started, an instrument which became and still is the greatest tool that operates in Italy, while the primacy of the greatest Italian telescope goes nowadays at the Telescopio Nazionale Galileo (TNG), built on the island of La Palma , Canary Islands.
IThe project for the construction of the 182 cm telescope required a considerable commitment on the part of all the technical staff of the Observatory. Due to the limited financial resources and to the fact that no special granting was given for the construction of the telescope, it was decided to do as much as possible in-house, with instruments more or less homemade. It was no mean feat to do it, but the competence and professionalism of the technicians of Asiago and the experience gained previously in the construction of the two Schmidt telescopes were essential for the success of the enterprise. All work related to the construction of the complex, from the foundations of the pillar, to the implementation of the telescope, from the equipment of the laboratory to the testing of optical parts, involved technicians and astronomers of Asiago Observatory. The entire frame was studied by the technicians of Asiago: Galazzi, Pertile and Rigoni, who then worked closely together with the staff of the company Sarti in Bologna for the construction and assembly of the several parts. Ruggero Stagni designed the movement pattern of the telescope and the electrical system, availing himself with the advice/consultancy of Sandro Centro, Institute of Physics, and of the technicians: Corà and Mosele. The choice of the optical tracking system and final tests were followed by prof. Cesare Barbieri.
The building that contains the telescope was designed by architects Cornoldi and Marcato.
The construction is surmounted by a dome made of stainless steel, the outer diameter is of 16 meters. The opening of the doors of the dome takes place with a hydraulic system.
A large hatch in the floor communicates with the underlying aluminizing room where is the vacuum bell of the Balzers company. Under the observation level there were also darkrooms, no longer in use after the transition from photographic plate to the CCD, in 1988.
Chronicle of the work: the first work performed at Cima Ekar was the central pillar, that supports the telescope, which emerged from the surrounding ground to a height of about 4 meters. The pillar was roomed-made filled with sand and gravel, to absorb any vibrations. It was completed in October 1970.
The work of the construction of the building that supported the dome, built around the pillar already on site, began in the spring of 1971
In May 1972, began the work to install the metal dome, completed after six months, with the exception of the inner shell. In December of the same year the ' building was completely habitable and technically usable..
When choosing the kind of telescope it was also discussed the opportunity to make a parabolic or Ritchey-Chrétien telescope. In the end it was decided for the first option and for an equatorial fork type frame.
The parabolic primary mirror of 1.82 meters and the secondary mirrors were made by the Grubb Parsons company of Newcastle, England, in about two years. After the processing of the primary mirror, it was examined in a tower of the same company running the classic test of Foucault and an interferometer test. The tests pointed out a narrow defect on the rim, 46 mm wide, a defect which was not, however, adjusted because the light of the ring did not exceed 10% of the total and also because there was a possibility to worsen the situation. In any case, the excellence of optics exceeded the requisites. After processing, the mirror was sent to the Royal Observatory in Herstmonceux Castle for the aluminizing. It was then shipped to Asiago.
Mirrors technical datas
|Total mass||1500 Kg||Total mass||67.4 Kg|
|Diameter||1820 mm||Diameter||580.0 mm|
|Thickness (external ring)||300 mm||Thickness (external ring)||110.3 mm|
|Diameter of central hole||383 mm||Radius of curvature||4594 mm|
|Radius of curvature||10840 mm||Distance M1-M1||3855 mm|
|Focal length||5393 mm||Corsa max||30 mm|
The time axis was in cast steel and had truncated cone profile; the fork was a structure of 20 mm thick iron plates that rests on the basement. All the pieces were designed by the technicians in Asiago and built at the workshops of Meccanica Sarti firm, in Bologna.
THE ASSEMBLY AT CIMA EKAR
On July 1972, the telescope was transported to Cima Ekar, when the dome was almost completed. The transport of mechanical parts and in particular of the mirror was a particularly tricky phase, because of the uneven surface of the narrow dirt road that led to Ekar.
The instrument was dismantled into four pieces: the base, the support with the entire time axis, the fork and the breech. The pieces were raised above the metal dome and entered the building through the two doors. Completed the dome, the optics were arranged, performed various tests of movement and balance weights. On the night of 8 March 1973 was obtained the first photograph (the Orion Nebula, M42).
In the same year in which the new telescope was accomplished, fell also the fifth centenary of the birth of Nicholas Copernicus. The University of Padua and the Astronomical Observatory wanted to give a special emphasis to the celebrations of this event, by naming the telescope 182 cm after the great Polish scientist.
The University and the Astronomical Observatory of Padua had particular reasons to commemorate with solemnity the figure of Copernicus. Between 1496 and 1503 Copernicus lived and studied in several Italian cities, establishing close links with the University of Bologna, Rome, Padua and Ferrara, in particular between 1501 and 1503 he attended the University of Padua as a medical student. It was in the Paduan period that Copernicus brought to full maturity his philosophical and scientific thought, thought that then gave rise to one of the greatest scientific revolution, and that found the final drafting in the “De revolutionibus Orbium Caelestium”.
The events were divided into three days: Padua, Verona, Asiago, and ended with the inauguration of the new Observatory Cima Ekar, branch of the Observatory of Padova, and the dedication to Copernicus of the telescope of 182 cm, the largest in Italy and one of the largest in Europe.
The inauguration took place on June 16, 1973, followed on 17 and 18 June by a international scientific meeting to Cima Ekar.
In his inaugural speech Leonida Rosino retraced the steps of the construction of the telescope Copernicus. He recalled the scientific contributions made by the Galileo telescope, the 122 cm opened in 1942: "... Three hundred and fifty scientific publications, often widely quoted in International reviews, evidence of the work we have done ..."
He also mentioned the scientific contributions made possible by the two Schmidt telescopes: “…With these tools 20 supernovae have been discovered among other things, some of which are of exceptional interest, and many others have been studied, bringing a significant contribution to the knowledge of these mysterious celestial objects. Programmes weren’t limited to the only study of supernovas of course... it will suffice here to mention the research on the planet Pluto, which have aroused much interest abroad, and the discovery of Maffei galaxies... "
In the words of Rosino there was much concern about the proliferation of lights in the Asiago urban area which made the observations increasingly difficult even at that time:
"In contrast to what happens in other countries of the East and West, the Italian State (it is a bitter realization) does not protect the plants/observatories for which has spent hundreds of millions, and the result is that the proliferation of light, which could easily be mitigated or screens, considerably reduces the efficiency of our greatest tools ... "
In the design and construction of the new instrument, as already mentioned, had a leading role the technical experts working at the Asiago Observatory, who had already been involved in the creation of the two Schmidt.
"I admit that was a cause of no little satisfaction for all of us to have brought alone to completion of a task so demanding, saving, among other things, hundreds of millions, compared to the cost of a telescope of the same power designed and supplied by specialized companies, "said Rosino at the end of his speech, thanking those, technicians and astronomers, who had made possible this enterprise ( Speech inaugural Leonidas Rosino).
THE SCIENTIFIC WORK
From the outset, the new telescope was used for the direct photography and for spectroscopy. Its focal length, sixteen meters, made possible to obtain, from the very first plates, images on a large scale that allowed researchers to see details of extended celestial objects such as galaxies and nebulae, and to work out on compact star systems as globular clusters.
The low-dispersion grating spectrograph Boller & Chivens (B&C) was immediately purchased and used from September 1973. Even the high-dispersion spectroscopy was part of the project and soon a Echelle REOSC spectrograph type was purchased, still one of the best tools working at the 182 cm Cima Ekar telescope.
Later on the low-resolution spectrograph (now installed at the Cassegrain focus of the telescope Galileo 122 cm) and the room were replaced with AFOSC (Asiago Faint Object Spectrograph and Camera), a tool which enables to create pictures, or operate in spectroscopy (technical information on the tools operating on the telescope Copernicus: here)
The first observations were carried out with photographic emulsion, both in direct photography that in spectrography with the aid of image intensifier. The transition from the photographic plate to CCD took place at the beginning of 1984, but the first solid state detector mounted on the telescope Copernicus (B & C spectrograph) was a RETICON (self scanned photo diode array), which dates back to 1978.
The number of observations made with the 182 cm with photographic emulsion is as follows:
|modalità||number||first plate||last plate|