  Data mining through large, multi-band ground-based surveys and the recent
availability of source catalogues from the {\it Gaia} space mission has led to
a surge in the number of known gravitationally lensed quasars, including some
unusual systems. One of these newly discovered systems is
GraL~J181730853+272940139. This system was reported in Delchambre et al. 2018,
and was identified as a quadruply lensed quasar candidate via a machine
learning search inside {\it Gaia} Data Release 2, where it consists of three
sources with maximum separation $1.8''$. Lemon et al. in prep (private
communications) confirmed it spectroscopically as a lensed quasar with source
redshift $z=3.07$. A mass model of this system has not been published to date,
and the highest resolution imaging data available is from PanSTARRS1
\citep{chambers16}, with seeing $\sim1.0''-1.3''$ in the $grizy$ filters. Here
we present the first mass model of J1817+2729, which includes the measured
relative astrometry and morphology of the lensing galaxy, using newly acquired
Subaru/FOCAS imaging.
