  We present $L$'-band imaging of the PDS 70 planetary system with Keck/NIRC2
using the new infrared pyramid wavefront sensor. We detected both PDS 70 b and
c in our images, as well as the front rim of the circumstellar disk. After
subtracting off a model of the disk, we measured the astrometry and photometry
of both planets. Placing priors based on the dynamics of the system, we
estimated PDS 70 b to have a semi-major axis of $20^{+3}_{-4}$~au and PDS 70 c
to have a semi-major axis of $34^{+12}_{-6}$~au (95\% credible interval). We
fit the spectral energy distribution (SED) of both planets. For PDS 70 b, we
were able to place better constraints on the red half of its SED than previous
studies and inferred the radius of the photosphere to be 2-3~$R_{Jup}$. The SED
of PDS 70 c is less well constrained, with a range of total luminosities
spanning an order of magnitude. With our inferred radii and luminosities, we
used evolutionary models of accreting protoplanets to derive a mass of PDS 70 b
between 2 and 4 $M_{\textrm{Jup}}$ and a mean mass accretion rate between $3
\times 10^{-7}$ and $8 \times 10^{-7}~M_{\textrm{Jup}}/\textrm{yr}$. For PDS 70
c, we computed a mass between 1 and 3 $M_{\textrm{Jup}}$ and mean mass
accretion rate between $1 \times 10^{-7}$ and $5 \times~10^{-7}
M_{\textrm{Jup}}/\textrm{yr}$. The mass accretion rates imply dust accretion
timescales short enough to hide strong molecular absorption features in both
planets' SEDs.

Earth and Planetary Astrophysics;Solar and Stellar Astrophysics