Gravitational Redshift

\[z = \sqrt{\frac{1 + 2\phi_{obs}/c^2}{1 + 2\phi_{emit}/c^2}} - 1\]
\[z = \sqrt{\frac{1 + 2(-6.26 \times 10^7)/(9 \times 10^{16})}{1 + 2(-1.9 \times 10^{11})/(9 \times 10^{16})}} - 1\]
\[z \approx +2.11 \times 10^{-6}\]
Observer