\begin{table}%t12
%\centering
\par
\caption{Recognized values for {\tt SPECSYS}\Ci, {\tt
    SSYSOBS}\Ci, and {\tt SSYSSRC}\Ci.}
\label{ta:specsys}
\begin{tabular}{lllrrl}
\hline\hline
Value & Definition & Magnitude & $\ell$ & $b$ & Reference \\
\hline
{\tt TOPOCENT} &Topocentric  &  0.0~km~~s$^{-1}$
               & -- & -- & \\
{\tt GEOCENTR} &Geocentric   &  0.5
               & -- & -- & \\
{\tt BARYCENT} &Barycentric & 30
               & -- & -- & Stumpff~(\cite{kn:S}) \\
{\tt HELIOCEN} &Heliocentric & 30
               & -- & -- & Stumpff~(\cite{kn:S}) \\
{\tt LSRK}     &Local standard of rest (kinematic) & 20
               & $\dag$ 56 & 23
               & Delhaye~(\cite{kn:D}), Gordon~(\cite{kn:G}) \\
{\tt LSRD}     &Local standard of rest (dynamic) & 16.6
               & 53 & 25 & Delhaye~(\cite{kn:D}) \\
{\tt GALACTOC} &Galactocentric & 220
               & 90 & 0 & Kerr \& Lynden-Bell~(\cite{kn:KLB})\\
{\tt LOCALGRP} &Local Group & 300
               & 90 & 0 & de Vaucouleurs~(\cite{kn:dV})\\
{\tt CMBDIPOL} & Cosmic microwave background dipole & 368
               & 263.85 & 48.25
               & Bennett et~al.~(\cite{kn:BHHJ}) \\
{\tt SOURCE}   &Source rest frame & any
               & -- & -- &  \\
\hline
\multicolumn{6}{l}{$\dag$ {\tt LSRK} is normally quoted as right
    ascension 18 hours, declination 30 degrees (1900).}
\end{tabular}
\end{table}