The Hubble Tension Bites the Dust: Sensitivity of the Hubble Constant
  Determination to Cepheid Color Calibration
  Motivated by the large observed diversity in the properties of extra-galactic
extinction by dust, we re-analyse the Cepheid calibration used to infer the
local value of the Hubble constant, $H_0$, from Type Ia supernovae. Unlike the
SH0ES team, we do not enforce a universal color-luminosity relation to correct
the near-IR Cepheid magnitudes. Instead, we focus on a data driven method,
where the measured colors of the Cepheids are used to derive a color-luminosity
relation for each galaxy individually. We present two different analyses, one
based on Wesenheit magnitudes, a common practice in the field that attempts to
combine corrections from both extinction and variations in intrinsic colors,
resulting in $H_0=66.9\pm 2.5$ km/s/Mpc, in agreement with the Planck value. In
the second approach, we calibrate using color excesses with respect to derived
average intrinsic colors, yielding $H_0=71.8\pm 1.6$ km/s/Mpc, a $2.7\,\sigma$
tension with the value inferred from the cosmic microwave background. Hence, we
argue that systematic uncertainties related to the choice of Cepheid
color-luminosity calibration method currently inhibits us from measuring $H_0$
to the precision required to claim a substantial tension with Planck data.
