of OGLE-BLG-ECL-157529 during primary eclipse is also shown. []{data-label=""}](T2.pdf "fig:"){width="8.5cm"}]{}

\[1\][![The parameter $\Sigma$ (O-C)$^{2}$ for the fits done to the light curve with data obtained at the maximum of the long cycle, as a function of mass ratio. The best 4$^{th}$ order polynomial fit is shown along with the 95% confidence band.[]{data-label=""}](SigmaQ.pdf "fig:"){width="8.5cm"}]{}

Discussion
==========

Overall qualitative interpretation
----------------------------------

The overall behavior of the light curve, especially the behavior of the secondary eclipse, can be interpreted in the terms of circumstellar material in the system. The changing shape of the secondary eclipse cannot be due to occultation by a star, but by a variable structure such as an accretion disk, surrounding the more massive star and formed by mass transfer from the Roche lobe overflow of the less massive star. This configuration is typical of semidetached Algols of the $\beta$ Lyrae type. What is not typical and it is unique for this system is the presence of a large amplitude long photometric cycle and the remarkable changes observed in the relative depths of the primary and secondary eclipses.

From the analysis shown in the previous section we might infer the existence of a large disk during the first observing epochs, 