\documentstyle[paasms4,pptwocol,pub]{article}
\begin{document}
 
\title{ABUNDANCE DETERMINATIONS IN EMISSION-LINE OBJECTS:\\
~\\
THE REVISED EMISSION LINE CHART}
\author{J.~B.\ Kingdon and R.~E.\ Williams\\
\\
Space Telescope Science Institute\\
\\
3700 San Martin Drive\\
\\
Baltimore, MD 21218\\
\\
kingdon@stsci.edu; wms@stsci.edu}

\begin{abstract}
We present here a revision of the Emission Line Chart (\cite{W95}) which is
based upon an extensive grid of photoionization models covering a wide range 
of hydrogen densities (n$_{H}$) and stellar temperatures (T$_{*}$). The
results of this grid are used to identify line ratios which are 
insensitive to conditions in the gas and which are therefore good for deriving
abundances. In addition, we classify these ratios according to the region of
(n$_{H}$, T$_{*}$) parameter space in which they are most useful.
\end{abstract}