ZTF J191814.28+010850.2: An eclipsing cataclysmic-variable candidate in the SW Sextantis period range

Abstract

We present a photometric study of ZTF J191814.28+010850.2, a short-period variable previously classified as an EA-type eclipsing binary. The analysis is based on ZTF observations in the g and r bands and additional time-series CCD photometry obtained on two nights. We derive an eclipse period of 0.1408529(3) d. The phased ZTF light curves show a deep primary eclipse, with an eclipse depth of about 2.8 mag in g and 2.0 mag in r, as well as indications of cycle-to-cycle variations outside eclipse. After excluding the primary eclipse and accounting for the remaining orbital modulation, robust locally weighted fits reveal a broad non-linear long-term brightness variation in both bands, with peak-to-peak ranges of about 0.56 mag in g and 0.46 mag in r. The deep eclipse, short orbital period and irregular variability suggest that the object is a cataclysmic-variable candidate and possibly a member of the SW Sextantis group. Time-resolved spectroscopy is required to confirm or refute the proposed classification and to test possible membership in the SW Sex class.