  A measurement of the mass of the Higgs boson in the diphoton decay channel is
presented. This analysis is based on 35.9 fb$^{-1}$ of proton-proton collision
data collected during the 2016 LHC running period, with the CMS detector at a
center-of-mass energy of 13 TeV. A refined detector calibration and new
analysis techniques have been used to improve the precision of this
measurement. The Higgs boson mass is measured to be $m_\mathrm{H} =$ 125.78
$\pm$ 0.26 GeV. This is combined with a measurement of $m_\mathrm{H}$ already
performed in the H $\to$ ZZ $\to$ 4$\ell$ decay channel using the same data
set, giving $m_\mathrm{H} =$ 125.46 $\pm$ 0.16 GeV. This result, when further
combined with an earlier measurement of $m_\mathrm{H}$ using data collected in
2011 and 2012 with the CMS detector, gives a value for the Higgs boson mass of
$m_\mathrm{H} =$ 125.38 $\pm$ 0.14 GeV. This is currently the most precise
measurement of the mass of the Higgs boson.
