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We report the discovery of a new eclipsing polar, MASTER OTJ061451.70-272535.5, detected as an optical transient by MASTER auto-detectionsoftware at the recently commissioned MASTER-SAAO telescope. Time resolved(10-20 s) photometry with the SAAO 1.9-m, and 1.0-m telescopes, utilizing theSHOC EM-CCD cameras, revealed that the source eclipses, with a period of 2.08hours (7482.9$\pm$3.5$\,$s). The eclipse light curve has a peculiar morphology,comprising an initial dip, where the source brightness drops to ${\sim}$50% ofthe pre-eclipse level before gradually increasing again in brightness. A secondrapid ingress follows, where the brightness drops by ${\sim}$60-80%, followedby a more gradual decrease to zero flux. We interpret the eclipse profile asthe result of an initial obscuration of the accretion hot-spot on the magneticwhite dwarf by the accretion stream, followed by an eclipse of both thehot-spot and the partially illuminated stream by the red dwarf donor star. Thisis similar to what has been observed in other eclipsing polars such as HU Aqr,but here the stream absorption is more pronounced. The object was subsequentlyobserved with South African Large Telescope (SALT) using the Robert StobieSpectrograph (RSS). This revealed a spectrum with all of the Balmer lines inemission, a strong HeII 4686\AA{} line with a peak flux greater than that ofH$\beta$, as well as weaker HeI lines. The spectral features, along with thestructure of the light curve, suggest that MASTER OT J061451.70-272535.5 is anew magnetic cataclysmic variable, most likely of the synchronised Polarsubclass.

Discovery, observations and modelling of a new eclipsing polar: MASTER OT J061451.70-272535.5