Light curves of AV Hya and DZ Cas

Using the Wilson-Devinney method, the photometric solutions with hot spots were deduced from their asymmetric light curves. The results indicate that both stars are Algol-type binaries, whose mass ratio, q_ph_, and fill-out factor of the primary, f_1_, are q_ph_=0.255(+/-0.002) and f_1_=81.2(+/-0.2)% for AV Hya, and q_ph_=0.093(+/-0.003) and f_1_=98.7(+/-0.3)% for DZ Cas.

Based on all available light minimum times, it is discovered that the O-C curve of each star could be described by a light-time orbit overlying on a downward parabola. Their periods and amplitudes are P_3_=37.2(+/-0.7)yr and A=0.0095'(+/-0.0006') for AV Hya, and P_3_=62.5(+/-1.0)yr and A=0.0183'(+/-0.0007') for DZ Cas. Cyclic variations may result from the light-time effect due to the third body.