We have measured accurate near-infrared magnitudes in the J and K bands of 39 Cepheid variables in the irregular Local Group galaxy IC 1613 with well-determined periods and optical VI light curves .
Using the template light curve approach of Soszyński , Gieren and Pietrzyński , accurate mean magnitudes were obtained from these data which allowed to determine the distance to IC 1613 relative to the LMC from a multiwavelength period-luminosity solution in the optical VI and near-IR JK bands , with an unprecedented accuracy .
Our result for the IC 1613 distance is ( m - M ) _ { 0 } = 24.291 \pm 0.014 ( random error ) mag , with an additional systematic uncertainty smaller than 2 % .
From our multiwavelength approach , we find for the total ( average ) reddening to the IC 1613 Cepheids E ( B - V ) = 0.090 \pm 0.007 mag , which is significantly higher than the foreground reddening of about 0.03 mag , showing the presence of appreciable dust extinction inside the galaxy .
Our data suggest that the extinction law in IC 1613 is very similar to the galactic one .
Our distance result agrees , within the uncertainties , with two earlier infrared Cepheid studies in this galaxy of Macri et al .
( from HST data on 4 Cepheids ) , and McAlary et al .
( from ground-based H-band photometry of 10 Cepheids ) , but our result has reduced the total uncertainty on the distance to IC 1613 ( relative to the LMC ) to less than 3 % .
With distances to nearby galaxies from Cepheid infrared photometry at this level of accuracy , which are currently being obtained in our Araucaria Project , it seems possible to significantly reduce the systematic uncertainty of the Hubble constant as derived from the HST Key Project approach , by improving the calibration of the metallicity effect on PL relation zero points , and by improving the distance determination to the LMC .