New open cluster Cepheids in the VVV survey tightly constrain near-infrared period--luminosity relations.

Classical Cepheids are among the most useful Galactic and nearby extragalactic distance tracers because of their well-defined period--luminosity relations (PLRs). Open cluster (OC) Cepheids are important objects to independently calibrate these PLRs. Based on Data Release 1 of the VISTA Variables in the Vía Láctea VVV survey, we have discovered four new, faint, and heavily reddened OC Cepheids, including the longest period OC Cepheid known, ASAS J180342-2211.0 in Teutsch 14a. The other OC-Cepheid pairs include NGC 6334 and V0470 Sco, Majaess 170 and ASAS J160125-5150.3, and Teutsch 77 and BB Cen. ASAS J180342-2211.0, with a period of log P = 1.623 (d) is important to constrain the slope of the PLR. The currently most complete JHKs Galactic Cepheid PLRs are obtained based on a significantly increased sample of 31 OC Cepheids, with associated uncertainties that are improved by 40 per cent compared with previous determinations (in the J band). The near-infrared PLRs are in good agreement with previous PLRs determined based on other methods. [ABSTRACT FROM AUTHOR]