1990 photometry of a small amplitude W UMa system LS Delphini

DifferentialUBV observations, carried out in 1990 observing season, of a small amplitude (0_.^m15 inV andB) W UMa system LS Del = HD 199497 are presented. Wavelength-dependent light variations from cycle to cycle indicate that the system is in a very active phase, probably due to magnetic flare activity or mass transfer in the system. An analysis of the minima times indicate a probable secular increase of the photometric period which requires a mass transfer from less massive to more massive component. If this is true then the reverse-algol model by Liuet al. (1988) for this system would not be valid.