\begin{table}%t1
\caption{\label{table1}The observed ratios between \lya~and \lyb~photon
radiances.}  
%\centerline
{
\small\begin{tabular}{lccc}
\hline\hline
Reference & Target  & Ratio & Instrument \\
\hline
\citet{Vernazza78} & quiet Sun  & 102 & ATM UV Spectrometer\\
\citet{Vernazza78} & coronal hole  & 108 & ATM UV Spectrometer\\
\citet{Vernazza78} & active region  & 42 & ATM UV Spectrometer\\
\citet{Lemaire78} & full Sun  & 79 & LPSP/OSO 8\\
\citet{Vial82} & prominence   & 77 & LPSP/OSO 8\\
\citet{Lemaire05} & full Sun  & 155 & SUMER/SOHO\\
\citet{Vial07} & prominence   & 114-217 & SUMER/SOHO\\
\citet{Curdt08} & quiet Sun & 188 & SUMER/SOHO\\
Current paper & quiet Sun  & 212-230 & SUMER/SOHO\\
\hline
\end{tabular}} 
\end{table}