Resolving the Discrepancy of Distance to M60, a Giant Elliptical Galaxy
  in Virgo
  There is a well-known discrepancy in the distance estimation for M60, a giant
elliptical galaxy in Virgo: the planetary nebula luminosity function (PNLF)
distance moduli for this galaxy are, on average, $~0.4$ mag smaller than the
values based on the surface brightness fluctuation (SBF) in the literature. We
present photometry of the resolved stars in an outer field of M60 based on deep
F775W and F850LP images in the Hubble Space Telescope obtained as part of the
Pure Parallel Program in the archive. Detected stars are mostly old red giants
in the halo of M60. With this photometry we determine a distance to M60 using
the tip of the red giant branch (TRGB). A TRGB is detected at $F850LP_{\rm
TRGB}=26.70\pm0.06$ mag, in the luminosity function of the red giants. This
value corresponds to $F814W_{0,\rm TRGB}=27.13\pm0.06$ mag and $QT_{\rm
TRGB}=27.04\pm0.07$ mag, where $QT$ is a color-corrected F814W magnitude. From
this we derive a distance modulus, $(m-M)_0=31.05\pm0.07{\rm(ran)}\pm0.06{\rm
(sys)}$ ($d=16.23\pm0.50{\rm (ran)}\pm0.42{\rm (sys)}$ Mpc). This value is
$0.3$ mag larger than the PNLF distances and $0.1$ mag smaller than the SBF
distances in the previous studies, indicating that the PNLF distances to M60 in
the literature have larger uncertainties than the suggested values.
