Schmidt telescopes



Angel 1


In 1958 the Observatory of Asiago was provided by a first  Schmidt 50/40 telescope (spherical mirror of 50 centimetres diameter, correcting plate of 40 centimetres diameter). It was designed by the technicians Galazzi and Rigoni of the Asiago Observatory and realized by Officine Sarti, in Bologna. The Schmidt 50/40 telescope was characterized by a field of 35 square degrees. Almost 6.000 photographic plates were obtained from 1958 untill 1966, when a new, larger Schmidt telescope was realized. This first photographic Archive pointed out the interesting results deriving from a wide field instrument. During its first eight operating years, the astronomers discovered some fifteen supernova, a lot of variable stars and flares stars.
Stated the high utility of a wide field telescope for the research activities of the Observatory, it was decided to increase the programme for the discovering of variable stars, especially of novae and supernovae. The new Schimdt 92/67 telescope (spherical mirror of 92 centimetres diameter, correcting plate of 67 centimetres diameter) was realized in two years, promoter Leonida Rosino, who was appointed Director of the Observatory of Asiago in 1953.


In 1961 Leonida Rosino passed two months in Lick Observatory: the research and the monitoring of galaxies clusters with a 50 centimetres astrograph struck his attention. After this experience, Rosino was determined to provide the Observatory of Asiago with a larger Schmidt telescope, the major of its kind in Europe. With the new  telescope it was possible to extend the observations for the discovering of supernova and flares stars - an already opened field with the "small" Schmidt telescope - and to start  the survey of galaxies clusters, quasars, RR Lyra, Wolf-Rayet stars.
The new site, called Stazione astronomica del Pennar dell'Osservatorio Astronomico di Padova, with the dome for the telescope, the machine shop, the dark room and the guestrooms, rose near to the dome of Galileo telescope.
The equatorial mounting for the telescope was realized by Officine Sarti (Bologna), in collaboration with the technical team of the Observatory consisting of the technicians Galazzi, Pertile and Rigoni. They followed the designing, construction and assembly of the telescope.
The optical system, with a correcting plate of 67 cm diameter in UBK7 Schott glass and a spherical mirror of 92 cm diameter in Duran-50 Schott glass, was realized by the English company Cox, Hargreaves & Thomson. The focal length is 215 cm (f/3.2). The telescope was equipped with two UV-transparent objective prisms, 4.5 degrees and 1 degree. The two prisms can also be used in direct or reversed combination.
The plate size is 20x20 cm and the corresponding field of view is 5x5 degrees. The imaging quality is excellent, without aberrations up to the border of the plates.


The Schmidt 92/67 telescope was inaugurated in 1967, in the bicentenary of Specola foundation. The new telescope was already fully operative: astronomers had obtained about a thousand plates before.
The mechanical an optical systems were excellent, as Leonida Rosino underlined during the opening cerimony. For the success of  such a project, he praised the expert technical team of Asiago Observatory:

"I would like to emphasize the skilfulness of the technicians: in September 4, 1965, we focalized the instrument with a first plate. Few menutes later we took the second plate, an image of M 31 the Andromeda galaxy, and it was an excellent image. It is really incredible that the first image made with a new instrument  is completely without aberrations"

The only obstacle for the future work of the telescope was already in those times the light pollution. Rosino drew  the attention to this fact, pointing out to politicians and administrators the degrading quality of the sky of Asiago. To this purpose he said:

"Light pollution is a crucial point for the future of the Observatory. We shall not rule out the hypothesis that it will be necessary in the future to move our instruments in another site ..." "... From year to year in Asiago and in all the highland, the lights are increasing in number and the nightsky, in the direction of Asiago, Gallio, Canove and Cesuna is suffering the light pollution ... ""... the territorial expansion causes the increasing of the artificial lighting. For thsi reason the future destiny of the Observatory is not clear". (Rosino's official talk of the opening cerimony, in Italian).

In the nineties the situation for the light pollution worsened. It was decided - Cesare Barbieri was the promotor - to move both the Schmidt telescopes to Mount Ekar, where in the meantime it was realized a new telescope, named Copernico, having a primary mirror with a diameter of 182 centimetres.
Mount Ekar is in a higher and in a more distant position from the centre of the city than Pennar site.


The Schmidt telescopes allowed the development of different research programmes, such as:

  •     Survey in galaxies for the discovery of supernovae (catalogue of all the supernovae discovered in Asiago).
  •     Survey of variables stars in nebulae.
  •     Discovery of flares stars (in Orion Nebula, Monoceros, Pleiades, Hyades, Praesepe ...).
  •     All-sky infrared survey for the discovery of brown dwarfs.
  •     Survey of the high galactic latitude for the discovery of RR Lyrae variables.
  •     Survey of peculiar galaxies, quasars and compact galaxies.
  •     Surveys with objctive prism for the discovery of emission lines stars, Wolf-Rayet stars, planetary nebulae, spectral classification

In a second time, other items were added to the Schmidt's programme, such as the discovery of new asteroids. The number of photographic plates taken with both the Schmidt telescopes, untill april 1999 is:

Schmidt 50/40 Schmidt 92/67
  imaging   18.411   imaging   16.729
  obiective prism   2006  obiective prism   1087


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