ZTF long-term (top left) and phase-folded (bottom left) light curves in g and r filters and the DBSP optical spectrum of 2CXO J044048.3+292434 (right). The gray lines represent the Keck Telluric Line List. The optical spectrum (top right) shows the hydrogen Balmer and helium emission lines and high-excitation He II 4686 Å emission line, giving a high line ratio He II/Hβ ≈ 0.64 (see Table 3). Optical and X-ray properties indicate that the object is a polar. Bottom right panel: Since two spectra taken 1.4 h apart do not show a significant radial velocity shift (a ≈ 1000 km/s shift would be expected if this were half of the orbital period and the system were viewed edge-on), the 1.3 h period is preferable. However, time-resolved spectroscopy for 2.6 h would be the only way to confirm the orbital period of this system, leading us to currently label the orbital period as either 1.3 or 2.6 h (see Sect. 5.1.1 for more details).