Analysis of theU B V light curves of TT hydrae by Kopal’s frequency domain method

The light curves of the totally eclipsing system TT Hya inUBV colours observed by Kulkarni and Abhyankar during 1973–77 have been analysed by Kopal’s frequency domain method with slight modification. We find y_s (primary) = 0.104 ± 0.005, y_g (secondary) = 0.215 ± 0.008 and i = 89‡ ± 1‡. The value of y_g obtained in this study is smaller than that determined earlier by Kulkarni and Abhyankar by the method of Russell and Merrill; this confirms the undersized nature of the secondary component.The ultraviolet colour excess of the secondary is also confirmed.