Multicolour high-speed photometry and H alpha spectroscopy of XY UMa

BVRI photometry and H alpha-line spectroscopy of the short-period RS CVn-bi nary XY UMa are presented. The light curves as a whole as well as the two e clipse minima are asymmetric. The light level after the primary minimum is lower by about 0.04-0.05 mag than that after the secondary one. Two cool sp ots on the primary with sizes 20 degrees and 10 degrees, temperatures 4630 and 4330 K at middle latitudes reproduced well the distortion curve in all colours. The observed Ha profile is quite wide and asymmetric at most the p hases out of the eclipses. The radial velocity curve is sinusoidal with sem iamplitude K-1 = 120.7 +/- 2.9 km/s. The corresponding mass function of the system is 0.082M(circle dot). The phase behaviour of the H alpha-profile i mplies contribution of emission of the chromospheric regions above the phot ospheric spots.