Observed-calculated eclipse minima of BX Tri. Archival data from Zhang et al. (2014) are marked with green crosses, those from Lohr et al. (2013) and Lohr (priv. comm.) with black dots. The DWARF project data (Pribulla et al. 2012) are displayed as blue diamonds. The XMM-Newton OM minimum is highlighted in red. The best-fit quadratic function based on the visual data is displayed as a broken line and yields a period change of (−0.018 ± 0.003) s yr⁻¹.