MULTIPERIODICITY IN THE ATYPICAL DELTA-SCT STAR AN LYN

New uvby data collected of AN Lyn together with the reanalysis of old data establish that this star is a multiperiodic pulsator. Three indep endent frequencies (v(1) = 10.1756, v(2) = 18.1309 and v(3) = 9.5598 c d(-1)) and some interactions be tween them are found to be present in the light curve. Changes in amplitude with a large time scale are conf irmed for the main frequency. Moreover, changes in amplitude are also present for the secondary frequencies, especially for v(3). After subt raction of the secondary frequencies from the light curves, the classi cal O-C method has been used to analyse the behaviour of the main peri od. A comparison is made between AN Lyn and the other two known delta Set stars with atypical light curves? i.e., V1719 Cyg and V798 Cyg. Ne w uvby data have been also collected for V1719 Cyg and the O-C method has been used to analyse the behaviour of the main period. It is found that the main pulsation of this star can be well described by means o f a linear ephemeris with a period of P = 0.(d)26729700 over the last eighteen years. Finally, analysis of the different data sets available in the literature do not reveal significative changes in the amplitud e of the main frequency of V1719 Cyg.