We report the discovery of a bright (V ~ 15), eclipsing, two-pole accreting magnetic cataclysmic variable (CV), a polar, as counterpart of the eROSITA and Gaia transients eRASSt 192932.9-560346 and Gaia21bxo. Frequent large amplitude changes of its brightness at X-ray and optical wavelengths by more than 4 magnitudes was indicative of a CV nature of the source. Identification spectra obtained with the 10m SALT telescope revealed the typical features of a magnetic CV, strong, broad HeI, HeII and hydrogen Balmer emission lines superposed on a blue continuum. Time-resolved photoelectric polarimetry revealed circular polarization to vary from -20% to +20%, and linear polarization from 0% to 10% confirming the system to be magnetic CV of the polar subclass. High cadence photometry revealed deep, structured eclipses, indicating that the system is a two pole accretor. The orbital period determined from the eclipse times is 92.5094 +- 0.0002 min. The X-ray spectrum is thermal only and the implied luminosity is L_X=2.2 x 10^(31) erg/s at the Gaia-determined distance of 376 pc.
The evolutionary history of ultra-compact accreting binaries. I. Chemical abundances and formation channel of the eclipsing AM CVn system ZTF J225237.05-051917.4 from HST spectroscopy
Hamburg Observatory, University of Hamburg（汉堡天文台，汉堡大学）；European Southern Observatory（欧洲南方天文台）；Department of Physics and Astronomy, Texas Tech University（德克萨斯理工大学物理与天文学系）；Department of Physics, University of Warwick（华威大学物理系）；Institut für Theoretische Physik und Astrophysik, University of Kiel（基尔大学理论物理与天体物理研究所）；São Paulo State University (UNESP), School of Engineering and Sciences（圣保罗州立大学（UNESP）工程与科学学院）；The Observatories of the Carnegie Institution for Science（卡内基科学机构天文台）；Department of Physics, University of California, Santa Barbara（加州大学圣塔芭芭拉分校物理系）；Departamento de Física, Universidad Técnica Federico Santa María（费德里科·圣玛丽亚技术大学物理系）；Institute of Science and Technology Austria（奥地利科学技术研究所）；Anton Pannekoek Institute for Astronomy, University of Amsterdam（阿姆斯特丹大学安东·潘农克天文研究所）
Circular polarimetry of suspect wind-accreting pre-polars II
Department of Physics and Astronomy, University of Sheffield（谢菲尔德大学物理与天文学系）；Armagh Observatory and Planetarium（阿马赫天文台和行星馆）；Department of Physics, University of Warwick（华威大学物理系）；Hamburger Sternwarte, University of Hamburg（汉堡天文台，汉堡大学）
IPHAS J190812.63+045728.1: A deeply eclipsing, X-ray bright cataclysmic variable with frequent outbursts
Universidade Federal de Sergipe（塞尔希培联邦大学）；Observatório Nacional（国家天文台）；Laboratório Nacional de Astrofísica（国家天体物理实验室）；NASA/GSFC（美国宇航局戈达德太空飞行中心）；University of Maryland, Baltimore County（马里兰大学巴尔的摩县分校）；Instituto Nacional de Pesquisas Espaciais（国家空间研究所）
