\begin{table}%t1
\caption{A complete list of all coordinate parameters referred to in this document.
Also included is the associated WCS~label where appropriate, and the units in
which the parameters are expressed.  Parameters given in meters can also be
expressed as relative to the solar radius~$R_\odot$.}
\label{params}
%\centering
\par
\begin{tabular}{lllp{4.5cm}}
\hline  \hline
Par & Units & WCS label & Description\\
\hline
$t$		& --	  &		& Observation date/time\\
$R_\odot$	& m	  &		& Solar radius
					  (\sci{{\approx}6.96}{8} m)\\
$D_\odot$	& m  & {\tt DSUN}	& Distance between the observer and Sun
					  center\\
$\Theta$	& deg & {\tt HGLT}	& Heliographic latitude\\
		&	  & {\tt CRLT}	& Synonym when used with {\tt CRLN}\\
$\Phi$		& deg & {\tt HGLN}	& Stonyhurst heliographic longitude\\
$\Phi\tinysub{C}$  & deg & {\tt CRLN}	& Carrington heliographic longitude\\
$L_0$		& deg	&		& Carrington longitude of central
					  meridian as seen from Earth\\
$r$		& m  & {\tt HECR}	& Radial distance from sun center\\
$h$		& m  & {\tt HECH}	& Radial distance from the solar
					  surface, \mbox{$h=r-R_\odot$}\\
$x$		& m  & {\tt SOLX}	& Heliocentric westward distance\\
$y$		& m  & {\tt SOLY}	& Heliocentric northward distance\\
$z$		& m  & {\tt SOLZ}	& Heliocentric observerward distance\\
$\rho$		& m  & {\tt SOLI}	& Heliocentric impact parameter\\
$\psi$		& deg & {\tt HCPA}	& Position angle from solar North\\
		&	  & {\tt HRLN}	& Synonym when used with {\tt HRLT}\\
$\theta_x$	& deg & {\tt HPLN}	& Helioprojective westward angle\\
$\theta_y$	& deg & {\tt HPLT}	& Helioprojective northward angle\\
$\theta_\rho$	& deg &		& Helioprojective impact angle\\
$\delta_\rho$	& deg & {\tt HRLT}	& Helioprojective-radial
					  declination angle, defined as
					  \mbox{$\theta_\rho - 90\degr$}\\
$d$		& m  & {\tt DIST}	& Radial distance from the observer\\
$\zeta$		& m  & {\tt HPRZ}	& Helioprojective analog of $z$,
					  defined as $D_\odot - d$\\
$\mu$		& --	  &		& Cosine of the angle to the surface
					  normal\\
$B_0$		& deg &			& Tilt of the solar North rotational
					  axis toward the observer
					  (heliographic latitude of the
					  observer)\\
$\Phi_0$	& deg &			& Stonyhurst heliographic longitude of
					  the observer\\
\hline
\end{tabular}
\end{table}