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Published online by Cambridge University Press: 14 August 2015
In the Astronomical Observatory of the town of Belogradchik a one-channel electrophotometer in the UBV system with pulse counting has been installed at the 60-cm Cassegrain telescope. the photoamplifier used is of the type EMI 6256B (1). With this telescope the author has carried out observations of 80 double galaxies during the period 1974 to the middle of 1977, using the differential method of observation with 3 diaphragms (24″, 54″ and 135″) depending on its diameter.