Identification of CW 1103+254 as a new magnetic variable.

The variations in linear and circular polarization are seen as suggesting a magnetically locked 114 min rotational period and resembling those of VV Pup in its one-pole state. Strong circular and linear polarization is seen during the entire bright phase, which lasts approximately 40 min. For the remainder of the period, the optical light is dominated by the unpolarized photospheric flux of the white dwarf primary and the high-excitation emission lines typical of AM Herculis systems. Linear and circular polarization data are presented, along with representative photometric data. In addition, time-resolved, high-resolution spectroscopic data are obtained for 1.6 periods of CW 1103+254. The emission line profiles are found to be complex and to be composed of a broad component, whose width varies from 350 km/s to 1400 km/s during the period, and one or two narrow components. The dramatic changes in line widths indicate strongly that converging flow velocities of approximately 1000 km/s are responsible for the observed radial velocities and line widths.