Program: GS-2021B-Q-123

We propose to measure a geometrical distance to IC 1613, based on the IRSB analysis of 10 Cepheids discovered in this galaxy. A precise (1%) distance will provide an opportunity to achieve a genuine breakhrough in the calibration of the TRGB method. We will also carry out a purely differential comparison of the IRSB-based Cepheid PL relations in the Milky Way, LMC and SMC, and IC 1613 ([Fe/H]~0, -0.3, -0.7, -1.0, respectively). This will significantly improve our knowledge about how exactly metallicity affects Cepheid absolute magnitudes. These results will have an immediate impact on the calibration of SN Ia with two independent methods, Cepheids and TRGB, and will therefore be crucial towards progress for a deeper understanding and eventual resolution of the problems related to the discrepant determinations of the Hubble constant.