  This note documents the methods used by the smartphone application,
"GalMass," which has been released on the Android Market. GalMass estimates the
halo virial mass (Mvir), stellar mass (Mstar), gas mass (Mgas), and galaxy gas
fraction of a central galaxy as a function of redshift (z<2), with any one of
the above masses as an input parameter. In order to convert between Mvir and
Mstar (in either direction), GalMass uses fitting functions that approximate
the abundance matching models of either Conroy & Wechsler (2009), Moster et al.
(2010), or Behroozi et al. (2010). GalMass uses a a semi-empirical fit to
observed galaxy gas fractions to convert between Mstar and Mgas, as outlined in
Stewart et al. (2009).
