MTM-500: History
50-cm Maksutov telescope MTM-500 was built at the Leningrad Optical and Mechanical Association (LOMO) in 1950. A high-sensitive television equipment was mounted at the coude focus in 1963. In 1964 A.N. Abramenko et al. recorded stars up to magnitude 20 over the 4-second exposition and this was a record at that time. The operative variation in modes of the TV equipment during the observations allowed V.V. Prokofjeva and V.P. Yepishev (1969) to acquire the entire light curve of the eclipsing variable star 442 Cas with an amplitude of more than 3.5 magnitude. A.N. Abramenko designed an electronic device for very short exposures. Photographs of the pulsar in the Crab Nebula with 2-ms exposures in 16 phases at the pulsation period equal to 32 ms were taken in 1970. During three oppositions of Mars about 100000 photographs of the planet in 4 and 10 spectral bands were taken, what made it possible to observe Martian clouds. In 1971 A.N. Abramenko and M.N. Naugolnaya were pioneers in observations of the beginning of the massive dust storm on Mars. The analysis of all TV observations of Mars allowed V.V. Prokofjeva to understand the authentic nature of the phenomenon of 'blue cleaning' on Mars and suggest the hypothesis about increasing dust in the Martian atmosphere. The whole experience has been summed up in the monograph "Television astronomy", edited by V.B. Nikonov.
In 1982 the telescope was equipped with a digital TV complex with isocon serving as an amplifier. The 20-cm meniscus telescope was mounted as a guide. With this guide it was possible to see on the monitor screen images of stars up to 15th magnitude in the field 50'x50' and up to 20th magnitude - at the MTM-500 with a field 10'x10'. These images were used for identification and manual guiding of the faint objects. With the 75-second exposition it was possible to measure brightness of stars up to 14th magnitude in the B, V or R (Johnson) filters with an accuracy of 1.0-1.5% and up to 18th magnitude ? with an accuracy of 10-15%. The simultaneous observations of objects up to 15th magnitude in the BVR bands were carried out. The original slitless spectrograph enabled to obtain absolute energy distribution of the point sources up to 14th magnitude with a spectral resolution of 60 A and 40 A and exposure time of several minutes. The telescope was used for observations of faint stars, asteroids, comets and other objects. The photometric observations allowed to discover the existence of such asteroids as 87 Sylvia (V.V. Prokofjeva and D.I. Demchik) and 423 Diotima (V.V. Prokofjeva and L.G. Karachkina). In 1994 as a result of spectral television surveillance V.V. Prokofjeva and V.P. Tarashchuk detected high-speed sodium clouds in the Jupiter’s magnetosphere before the collision with a fragment Q of the Shoemaker-Levy 9 comet.
The long-term spectrophotometric observations of asteroids were performed with a digital television complex MTM-500C. To accomplish this task, the modernization of the MTM-500 was implemented with the aim of accurate guiding asteroids on the celestial sphere. The new techniques for obtaining spectra of the asteroids with brightness from 7m to 12m allowed to fulfil accurate relative intensity measurements of about 1% with 0.5-6-minute exposure and spectral resolution of 60 A or 40 A. During 5 years more than 3500 spectra of E-, S-, M- asteroids were acquired.
In 2014 a CCD camera with a set of UBVRI filters was mounted on the telescope and systematic observations of exoplanet transits were started.