(a) Phase-folded light curve of ZTF J191457.72+270231.3 on the revised ephemeris of Equation (1). C82 Nastro Verde CCD photometry (black) and ZTF r (orange), two cycles shown. The Nastro Verde observations pre-date the ZTF discovery by more than three years and define the new epoch of maximum light. (b) O − C diagram from 26 times of maximum spanning 39,089 cycles (∼10.1 yr). Weighted linear fit (dashed) and quadratic fit (solid) shown. (c) Intra-cycle color variation traced by simultaneous ZTF g − r pairs; solid line marks the binned median.