  Time-delay cosmography uses strong gravitational lensing of a time-variable
source to infer the Hubble Constant. The measurement is independent from both
traditional distance ladder and CMB measurements. An accurate measurement with
this technique requires considering the effects of objects along the line of
sight outside the primary lens, which is quantified by the external convergence
($\kappa_{\rm{ext}}$). In absence of such corrections, $H_0$ will be biased
towards higher values in overdense fields and lower values in underdense
fields. We discuss the current state of the methods used to account for
environment effects. We present a new software package built for this kind of
analysis and others that can leverage large astronomical survey datasets. We
apply these techniques to the SDSS J0924+0219 strong lens field. We infer the
relative density of the SDSS J0924+0219 field by computing weighted number
counts for all galaxies in the field, and comparing to weighted number counts
computed for a large number of fields in a reference survey. We then compute
weighted number counts in the Millennium Simulation and compare these results
to infer the external convergence of the lens field.Results. Our results show
the SDSS J0924+0219 field is a fairly typical line of sight, with median
$\kappa_{\rm{ext}} = -0.012$ and standard deviation $\sigma_{\kappa} = 0.028$.
