deletions | additions       diff --git a/Problem 2.tex b/Problem 2.tex  index b5e7f34..21eb72a 100644  --- a/Problem 2.tex  +++ b/Problem 2.tex 
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\frac{A_V}{\rm{N_H}}=5.3\times10^{-22}~\rm{mag~cm^{2}}  \end{equation}  \noindent which is Draine's Eq.~21.7. To give a feel for our systematic uncertainty in this conversion, let's add an uncertainty term such that $R_V=3.1\pm1$. Next we need to model the gas between us and the galactic center. Let's ignore the Sgr B2 molecular cloud, at first. Making the assumption that the ISM composition is effectively isotropic on Galactic scales, we will adopt the characteristic ISM phase densities and filling factors from Draine's Table 1.3.  \begin{tabular}  \end{tabular}