A minimum in the light curve of the classical symbiotic star YY Her in 2001

We present new photometric UBV RI observations of the classical symbiotic star YY Her in 2001. A deep secondary minimum with an amplitude of (ProQuest: Formulae and/or non-USASCII text omitted; see image) in V was found in its light curve during this period. The color characteristics of the primary and secondary minima are compared. We show that the star reddens during its primary minimum and blues during its secondary minimum in the U-B and B-V color indices. In the red spectral band, the color of YY Her does not change as it passes through its secondary minimum. We estimate photometric parameters of the radiation sources that disappear from the field of view when the star is at minimum light. Based on observational data, we investigate various models for the formation of the secondary minimum.[PUBLICATION ABSTRACT]