The AM Her System RX J1844.2+4454/2MASS J18441496+4454091/ZTF18aapobha*

Abstract Based on ROSAT All-Sky Survey data and optical follow-up observations, we report observations of the cataclysmic variable RX J1844.2+4454/2MASS J18441496+4454091/ZTF18aapobha. The very soft X-ray spectrum, combined with a characteristic optical light curve, large equivalent widths of Balmer and He II lines, and cyclotron features in the optical spectrum, suggests a magnetic nature of AM Her type. The main parameters are an orbital period of 234.5 minutes, a luminosity of 2.4 × 10 34 erg s −1 , and a magnetic field strength in the 46–115 MG range.