Consistent Calibration of the Tip of the Red Giant Branch in the Large
  Magellanic Cloud on the Hubble Space Telescope Photometric System and a
  Re-determination of the Hubble Constant
  We present a calibration of the Tip of the Red Giant Branch (TRGB) in the
Large Magellanic Cloud (LMC) on the HST/ACS F814W system. We use archival HST
observations to derive blending corrections and photometric transformations for
two ground-based wide-area imaging surveys of the Magellanic Clouds. We show
that these surveys are biased bright by up to ~0.1 mag in the optical due to
blending, and that the bias is a function of local stellar density. We correct
the LMC TRGB magnitudes from Jang & Lee (2017) and use the geometric distance
from Pietrzynski et al. (2019) to obtain an absolute TRGB magnitude of
M_F814W=-3.97+/-0.046 mag. Applying this calibration to the TRGB magnitudes
from Freedman et al. (2019) in SN Ia hosts yields a value for the Hubble
constant of H_0=72.4+/-2.0 km/s/Mpc for their TRGB+SNe Ia distance ladder. The
difference in the TRGB calibration and the value of H_0 derived here and by
Freedman et al. (2019) primarily results from their overestimate of the LMC
extinction, caused by inconsistencies in their different sources of TRGB
photometry for the Magellanic Clouds. Using the same source of photometry
(OGLE) for both Clouds and applying the aforementioned corrections yields a
value for the LMC I-band TRGB extinction that is lower by 0.06 mag, consistent
with independent OGLE reddening maps used by us and by Jang & Lee (2017) to
calibrate TRGB and determine H_0.
