# The Carnegie-Chicago Hubble Program. II. The Distance to IC 1613: The Tip of the Red Giant Branch and RR Lyrae Period-Luminosity Relations

## TL;DR

This study provides precise distance measurements to the dwarf galaxy IC 1613 using the Tip of the Red Giant Branch and RR Lyrae stars, contributing to the calibration of the local distance ladder for Hubble constant estimation.

## Contribution

It offers new high-precision distance estimates to IC 1613 using Population II stars, employing both TRGB and RR Lyrae methods, and compares these to existing measurements.

## Key findings

- Distance moduli from TRGB and RR Lyrae are consistent within uncertainties.
- High-precision TRGB magnitude measured at I=20.35.
- Distances agree with recent literature, supporting Population I and II star consistency.

## Abstract

IC 1613 is an isolated dwarf galaxy within the Local Group. Low foreground and internal extinction, low metallicity, and low crowding make it an invaluable testbed for the calibration of the local distance ladder. We present new, high-fidelity distance estimates to IC 1613 via its Tip of the Red Giant Branch (TRGB) and its RR Lyrae (RRL) variables as part of the Carnegie-Chicago Hubble Program, which seeks an alternate local route to \ho using Population II stars. We have measured a TRGB magnitude I=20.35+/-0.01 (statistical)+/-0.01 (systematic) using wide-field observations obtained from the IMACS camera on the Magellan-Baade telescope. We have further constructed optical and near-infrared RRL light curves using archival BI- and new H- band observations from the ACS/WFC and WFC3/IR instruments aboard the Hubble Space Telescope (HST). In advance of future Gaia data releases, we set provisional values for the TRGB luminosity via the Large Magellanic Cloud and Galactic RRL zero-points via HST parallaxes. We find corresponding true distance moduli \mu(TRGB)=24.30+/-0.03 (statistical)+/-0.05 (systematic) and \mu(RRL)=24.28+/-0.04 (statistical+systematic). We compare our results to a body of recent publications on IC 1613 and find no statistically significant difference between the distances derived from stars of Population I and II.