From the Inner to Outer Milky Way: A Photometric Sample of 2.6 Million
  Red Clump Stars
  Large pristine samples of red clump stars are highly sought after given that
they are standard candles and give precise distances even at large distances.
However, it is difficult to cleanly select red clumps stars because they can
have the same T$_{\mathrm{eff}}$ and log $g$ as red giant branch stars.
Recently, it was shown that the asteroseismic parameters, $\rm{\Delta}$P and
$\rm{\Delta\nu}$, which are used to accurately select red clump stars, can be
derived from spectra using the change in the surface carbon to nitrogen ratio
([C/N]) caused by mixing during the red giant branch. This change in [C/N] can
also impact the spectral energy distribution. In this study, we predict the
$\rm{\Delta}$P, $\rm{\Delta\nu}$, T$_{\mathrm{eff}}$ and log $g$ using 2MASS,
AllWISE, \gaia, and Pan-STARRS data in order to select a clean sample of red
clump stars. We achieve a contamination rate of $\sim$20\%, equivalent to what
is achieved when selecting from T$_{\mathrm{eff}}$ and log $g$ derived from low
resolution spectra. Finally, we present two red clump samples. One sample has a
contamination rate of $\sim$ 20\% and $\sim$ 405,000 red clump stars. The other
has a contamination of $\sim$ 33\% and $\sim$ 2.6 million red clump stars which
includes $\sim$ 75,000 stars at distances $>$ 10 kpc. For |b|>30 degrees we
find $\sim$ 15,000 stars with contamination rate of $\sim$ 9\%. The scientific
potential of this catalog for studying the structure and formation history of
the Galaxy is vast given that it includes millions of precise distances to
stars in the inner bulge and distant halo where astrometric distances are
imprecise.
