High-Amplitude, Rapid Photometric Variation of the New Polar MASTER OT   J132104.04+560957.8
  We present photometric and spectroscopic observations of the cataclysmic variable MASTER OT J132104.04+560957.8 which strongly indicate that it is a polar with an orbital period of 91 minutes. The optical light curve shows two maxima and two minima per orbital cycle, with considerable variation in the strength of the secondary maximum and in the morphology and depth of the minima. 
Colin Littlefield, Peter Garnavich, Katrina Magno, Marc Murison,   Shanel Deal, Colin McClelland, Benjamin Rose
astro-ph.SR