BRIEF HISTORY

The formal establishing of the Department of Image Processing (DIP) at the Astronomical Observatory of Kharkov National University should be referred to the middle of the 70-ths while its origin can be traced up to the 60-ths when the first attempts to correct the errors of photometry of planetary discs for the effects of atmospheric blurring had been undertaken at the AO KhNU, [1,2]. Just at that time the problem of seeing through the turbulent atmosphere became of great importance for astronomical studies, as well as for some applied tasks connected with the international safety monitoring. As a result, a great number of new methods to obtain information about the fine spatial structure of astronomical objects had appeared which stimulated development of the observing and processing technique, and, that is even more important, a noticeable progress in understanding the problem has been achieved. Investigation of statistical parameters of the atmosphere responsible for the image degradation was fulfilled by the DIP staff in 1974-80, [8], which had helped them to formulate the general strategy to reach the high angular resolution in ground-based observations, [17].

Application of interferometric technique to telescopic observations became an important step in overcoming the natural limit of resolution posed by the atmosphere. However, all these methods needed a rather powerful image processing technique. But at that time a digital processing technique could not provide processing of high-informative astronomical images in a reasonable time. In addition, no digital light detectors existed at that time. That is why a coherent optical processor became the most natural instrument to fulfil image processing in the 60-ths, when the first industrial lasers appeared.

The first attempt to apply a coherent optical device for processing astronomical images was undertaken at the AO KhNU in 1970. By 1973 a coherent optical processor with the excellent technical parameters had been created by the efforts of the DIP staff, [3,4], and for long became the main instrument for solving a wide range of problems connected with image processing, [5,6,7,11,13,15-17,19,21,22]. Speckle interferometry of red giants and close binaries with the BTA telescope, [5, 7,11], and spatially resolved photometry of gravitational lens systems [20-23] should be noted especially. At the same time, special devices and light detectors for high-resolution imaging were designed and built in 1980-90 by the efforts of our own, such as, e.g., speckle cameras for the observatories in Abastumani (Georgia), Maidanak (Uzbekistan), and Kharkov (Ukraine), [12], a device for high-precise determination of scale at a telescope focal plane, [10], and a fast digital microdensitometer for photometry of high-informative photographic images, [18]. In 1989, a 50-cm telescope with the mirror of diffraction-limited quality was created by the DIP staff and mounted at the high-altitude Maidanak Observatory.

Since the end of the 80-ths, with the advent of digital CCD-detectors and personal computers, which provide much greater potentiality of image recording and processing, the field of interests had naturally changed and shifted towards more faint (and much more interesting!) extragalactic objects. In 1995, the CCD images of the Q2237+0305 gravitational lens system (the Einstein Cross) [21] were obtained for the first time with the new 1.5-meter telescope on Maidanak Mountain, - the astronomical site with the excellent seeing conditions. Since that time gravitational lens systems are being intensively investigated in cooperation with the Institute of Radio Astronomy of Nat. Ac. Sci. of Ukraine (Kharkov), Sternberg State Astronomical Institute (Moscow) and Ulugh Beg Astronomical Institute of Nat.Ac.Sci. of Uzbekistan (Tashkent), [20-23]. In 1997-98, the monitoring of brightness and colour variations in the Einstein Cross gravitational lens system was being carried out in the framework of the international CRDF grant program, [22], with Prof. B. Paczynski (Princeton University) as a Coordinator from the U.S. party.