Time-resolved Observations of the Short Period CV SDSS J123813.73-033933.0

We present simultaneous spectral and photometric observations of SDSS J123813.73-033933.0. From H® radial velocity measurements we determined the orbital period of the system to be 0:05592 + or - 0:00002 days (80.53 min). The spectrum shows double Balmer emission lines °anked by strong, broad absorption, indicating a dominant contribution from the white dwarf. The photometric light curve shows complex variability. The system undergoes cyclic brightening up to 0.4 mag which are semi-periodical on short time scales with periods of the order of 7-12 hours. We also detect 40.25 min variability (~0.15 mag) in the light curve, that corresponds to half the orbital period. Its amplitude increases with the cyclic brightening of the system.