Period variations of the eclipsing system DI Pegasi

The period variations of DI Peg were checked in 1980, and the results are presented. Two primary minima were observed photoelectrically in yellow light, and the times of primary minima are shown. Epochs of minimum light were determined using the Hertzsprung (1928) method as modifed by Kwee and Woerden (1956). A period diagram covering some 50 years is presented. It indicates that two significant changes in the orbital period of DI Peg have been recorded, a sudden period increase around 1946 and an almost identical period decrease around 1969. The epochs of minimum light obtained between 1945 and 1970 were introduced into a least squares regression analysis to obtain an average period of 0.7118177 days during this period.