History

Determining the date of the first conscious observation of a variable star in our lands is difficult. Many will surely recall the names Tycho Brahe, Johannes Kepler, and Tadeáš Hájek of Hájek in this context. However, in their case, the observations were more or less accidental. Therefore, let us move more than two centuries closer to the present in our considerations. In the 1870s to 1890s, the Prague professor Vojtěch (Adalbert) Šafařík made more than twenty thousand observations (brightness estimates). Let us, therefore, credit him with the primacy, and a doubly valuable one at that. He was our first systematically working observer of variable stars and, to this day, also the most prolific. Among his followers, let us at least mention Ladislav Pračka, who, in addition to his own observations, was responsible for publishing most of Šafařík’s observations, and Václav Rosický, who observed variable stars at the Prague University Observatory from 1886 to 1900. In his articles, Šafařík recommended certain stars for spectral research. This began to be pursued by the Astronomical Institute of Charles University under the leadership of Gustav Gruss from the early 1890s. However, the first observations of 20 variable stars were made visually in 1894 by Gruss together with Václav Láska, using Argelander’s method (Gruss, Láska, 1895). Later that same year, they also published spectroscopic observations. Although the number of these observations is not very large, they represent the beginning of astrophysical research in our country.

At the beginning of the 20th century, only a few isolated observers worked in our lands. However, none of them achieved the significance of Šafařík, Pračka, or Rosický. A new impetus for the development of astronomy was the founding of the Czech Astronomical Society in 1917. 1917. Seven years later, the Section of Variable Star Observers was established within it. Its first chairman was Bohumil Hacar. A dozen founding members made several hundred observations of irregular stars. Most of their observations were published in the bulletin of the French society AFOEV. The section became a true organizer of activity in the field of amateur variable star research in our country.

At the turn of the 1920s and 1930s, the leadership of the section changed hands among František Schüller, Rostislav Rajchl, and in 1930, the helm was taken by the only seventeen-year-old Zdeněk Kopal. He was not only a very active observer – making over ten thousand observations between 1929 and 1932 – but also an excellent organizer: he began publishing the section’s bulletin, compiled summaries of observation counts, drew charts, and established extensive contacts with foreign societies and observers. Under Kopal’s leadership, the section achieved unprecedented prosperity, both in the scope of its activities and the number of its members, and became one of the European centers of amateur variable star research.

In 1933, Vladimír Vand took over the leadership of the section. At that time, the observational activity of František Kadavý was at its peak; between 1929 and 1936, he made more than thirteen thousand observations (brightness estimates), thus becoming the most active Czechoslovak observer of the First Republic period. Before the start of the Second World War, the section’s leadership was held in turn by Vladimír Strýček, Alois Vrátník, and Vladimír Ruml. The result of the section’s work was several thousand observations annually, mainly of irregular and semi-regular variable stars. The section continued its work even during the occupation until May 1943, when it was dissolved. However, its members continued processing the extensive observational material even after that. 28. 6. In 1944, the section was revived under the leadership of V. Strýček, first as the Group of Variable Star Observers and after liberation (from September 1945) again as a section, but no longer of the Czech, but of the Czechoslovak Astronomical Society. In 1947, Záviš Bochníček became the chairman of the section, the third observer in the section to have over ten thousand observations (brightness estimates) to his credit.

At the beginning of the 1950s, the section’s activities and its observational program gradually fell into crisis. At the Brno conference for variable star research in April 1953, a resolution was passed that was intended to generously address the situation in Czechoslovak variable star research on both the amateur and professional fronts, but of the four proposed observational programs, only two ‘took off’. The first of these – the observation of irregular and semi-regular variable stars, R CrB-type variable stars, and novae – essentially survived for historical reasons in a slowly dying section, whose activities were officially and definitively terminated by the reorganization of the Czechoslovak Astronomical Society in 1953. 1957. Unfortunately, with the demise of the then section, many archival materials also disappeared, especially a large amount of unprocessed and unpublished observations. The second program – the research of unmonitored eclipsing variable stars and eclipsing binaries with variable periods (led by B. Hacar) – was a novelty proposed at the Brno conference.

And it was precisely to these observations that the then director of the Brno Observatory, Oto Obůrka, turned in the mid-1950s. For several years thereafter, both mentioned observational programs ran concurrently; however, beginning observers increasingly turned to the Brno Observatory program. This observational program, for example, allowed them to obtain ‘tangible’ results even within a single night. As early as June 1955, O. Obůrka organized a gathering for observers at the Brno Observatory and tirelessly promoted variable star observation through the astronomical press. In 1958, a group of observers was working in Brno, training in the use of a visual photometer. However, systematic observations did not materialize. And so the true, historical milestone in amateur variable star research in Czechoslovakia became the astronomical expedition held from August 14 to 27, 1960, in Piešťany. Sixteen observers (including O. Obůrka and his guest K. Kordylewski from Poland) devoted themselves to variable stars there, making 707 estimates (the first on August 21, 1960) and obtaining 22 times of minima. It was on this expedition, after years of searching and preparation, that the foundation was laid for the current Brno observational program. Initially, this program included not only observations of eclipsing binaries but also of short-period Cepheids, and only after several years did it focus exclusively on eclipsing variable stars.

Thus, from the summer of 1960, the Brno Observatory became the de facto center of amateur variable star research in Czechoslovakia. Observation results were concentrated there, their processing and publication took place there, and observers received all necessary materials and aids (charts, predictions, …) from there. The program was headed by the then director of the Brno Observatory and first chairman of the newly formed section for variable star observers, O. Obůrka. Particularly through his efforts, nationwide summer practicals began to be held at the Brno Observatory from 1961, and seminars for variable star observers from 1963. Obůrka also published the first observation results, initially through the journal Bulletin of the Astronomical Institutes of Czechoslovakia and later in the Works of the People’s Observatory and Planetarium in Brno (Obůrka, 1966, 1967; Obůrka, Šilhán, 1970; Šilhán, 1971). Unfortunately, other work commitments increasingly prevented him from devoting time to variable stars, so several other people took turns leading the program. Let us at least mention Vladimír Znojil or Jindřich Šilhán, the latter of whom still participates in leading the program today. These two influenced the observational program in a positive way; otherwise, however, observational activity declined at the end of the 1960s. In 1972, Zdeněk Pokorný took over the leadership of the program. Together with J. Šilhán and K. Raušal, he published an extensive guide for observers a year later (Pokorný, Šilhán, Raušal, 1973). He began publishing an irregular Information Bulletin for variable star observers, attempted to transfer data and their processing to a computer, and continued publishing observation results. In 1978, he ‘moved’ the summer practicals from Brno to Ždánice (with interruptions until 2002) and Vyškov (from 1986 to the present). In 1982, Zdeněk Mikulášek became the program leader. He took over the amateur variable star research program at a time when one of its peak periods was beginning. In addition to the practicals in Ždánice and Vyškov, practicals, gatherings, or expeditions were (and in many places still are) held in Třebíč, Držková (Zlín group), Zachotín (Prague expedition), Plzeň, and also in several locations in Slovakia. Activity within the program expanded considerably, and it was only a matter of time before its organization became unmanageable by one or two people. This indeed occurred at the end of the 1980s. Therefore, in 1990, at the instigation of Miloslav Zejda, the program leadership implemented a extensive reorganization. The committee (until then more or less formally existing) of the Section of Variable Star Observers of the CAS also became involved in the work associated with the program’s implementation. A group leadership of the program was formed, consisting of section chairman Z. Mikulášek, vice-chairman Pavel Suchan, secretary J. Šilhán, and committee members M. Zejda (responsible for leading the data processing group), Dalibor Hanžl (head of the photometric group), Jiří Borovička (head of the bibliographic group), Antonín Dědoch, Petr Hájek, Petr Kučera, Alexandr Slatinský, and Igor Kudzej. During the following year, A. Slatinský and P. Suchan resigned from the section committee, with J. Borovička replacing the latter. Although the focus of daily organizational work, associated with considerable material support, remained on the shoulders of the Brno Observatory, its employees, and collaborators, the section committee facilitated this work for them in many areas. However, the ‘executive director’ of the program was still a professional staff member of the Brno Observatory, and from 1990 its director, Z. Mikulášek. In 1992, due to work commitments, he resigned from this post. The baton was passed to M. Zejda, who replaced Z. Mikulášek as section chairman at the end of 1993. A change also occurred in the publication of information for observers. The irregular Information Bulletin (newsletter) was replaced in 1990 by the bulletin Perseus, which is currently published four times a year. Its editor-in-chief became Eva Neureiterová (Šafářová). From 1994 to 1998, it was M. Zejda, and from 1999, Petr Sobotka. The transformation of the program’s leadership was essentially completed only in 1992, when the group of observers affiliated with the Brno observational program adopted the name B.R.N.O. (Brno Regional Network of Observers). How large is this group? Judge for yourselves. Between 1960 and 1992, seven hundred observers contributed their own observations, of whom almost two hundred were active in the last three years (1990-92). Since 1960, around ten thousand observational series have been collected in Brno, the results of which were published in thirteen issues of the Works of the M. Koperník Observatory and Planetarium in Brno (originally Works of the People’s Observatory and Planetarium in Brno) (Obůrka 1966, 1967; Obůrka, Šilhán 1970; Šilhán, 1971; Mikulášek 1972, 1985, 1986; Pokorný 1974, 1976, 1978, 1982; Mikulášek, Šilhán 1988; Mikulášek, Šilhán, Zejda 1992).

In the mid-1990s, the program leadership began to offer the possibility of processing, submitting for processing, or publishing observations of variable star types other than eclipsing binaries. Independently of this initiative, in 1996 L. Brát, P. Hájek, and P. Sobotka founded a project for observing intrinsic variable stars within the section. The observers participating in the project later formed the Medúza group within the section. This restored the opportunity for amateurs to observe intrinsic variable stars, as was the case in the first half of our century.

At the end of 2001, at the instigation of M. Zejda, a group of eclipsing binary observers created the Prosper project, which focuses on (possible) eclipsing binaries without known light elements. The project manager became D. Motl.

Currently, members of the section participate in a number of research projects on various types of variable stars, for example within the HIPPARCOS project, the symbiotic star study program of the Astronomical Institute of the Slovak Academy of Sciences in Tatranská Lomnica, etc. B.R.N.O. maintains active written and personal contacts with representatives of many foreign variable star observer societies.

At this point, however, it is necessary to mention other activities in the field of variable stars in the Czech lands and Slovakia. Variable stars are also observed by participants in the Amateur Sky Survey project. These are mostly irregular, semi-regular, or Cepheid variable stars, as is the case with the observations of several Czech and Slovak observers who participate in the work of the American AAVSO program. Since 1992, Czech astronomers have been informed about important discoveries through Express Astronomical Information (EAI), which also announces various observational campaigns for specific objects. Within these campaigns, Czech observers have also discovered two new variable stars (GSC 1383.0600 by Petr Pravec, 1993; GSC 4383.0384 by Kamil Hornoch and Jan Kyselý, 1993). Another variable star (near M 27) was discovered accidentally in 1991 by Leoš Ondra.

ADDED IN 2007…

A new era of variable star observation began at the turn of the millennium. From the beginning of the 21st century, CCD technology became accessible to ordinary amateur observers. With its help, observers are able to obtain highly accurate and objective measurements of stellar brightness, and new possibilities for variable star research emerged.

Many observers began observing eclipsing binaries with renewed enthusiasm and new technology, determining precise times of minima. The advent of CCD technology revealed the triple-star nature or orbital eccentricity of many objects. New variable stars began to appear at a rapid pace, and during the first six years of the 21st century, Czech observers discovered more than 100 of them.

Changes also occurred within the Section of Variable Star Observers. Due to societal changes and as a result of personnel changes in the leadership of the Brno Observatory – the Section’s seat until then – the Section of Variable Star Observers became separated from the M. Koperník Observatory and Planetarium in Brno. Hand in hand with this came a change in the position of Section Chairman. From 2005, Luboš Brát became its chairman.