\begin{table}%T1
\par
\caption{{\it IUE}~spectra used in this work.}\label{t1}
%\centerline
{
\begin{tabular}{lrcr|lrcr}  
\hline\hline
Spectrum  &  Exp. (s)  &  Aperture$^{*}$  & Obs. date &
Spectrum  &  Exp. (s)  &  Aperture$^{*}$  & Obs. date    \\  \hline
SWP02326  &  1200  &  L      &  18 Aug. 1978  &  SWP40148  &   900  &  L      &  20 Nov. 1990  \\
SWP02334  &  6000  &  L      &  18 Aug. 1978  &  SWP40149  &  9000  &  L      &  20 Nov. 1990  \\
SWP02953  &  2400  &  S      &  13 Oct. 1978  &  SWP43006  &   720  &  L      &   4 Nov. 1991  \\
SWP05669  &  1800  &  S      &  29 Jun. 1979  &  SWP43007  & 13~980  &  L      &   4 Nov. 1991  \\
SWP06353  &  1800  &  S      &   2 Sep. 1979  &  SWP46060  &  2700  &  L      &   5 Oct. 1992  \\
SWP06355  &  4200  &  S      &   2 Sep. 1979  &  SWP46142  &   900  &  L      &   6 Nov. 1992  \\
SWP06527  &  3960  &  L      &  15 Sep. 1979  &  SWP47697  &   720  &  L      &  20 May 1993  \\
SWP06809  &   900  &  L      &   9 Oct. 1979  &  SWP50707  &   720  &  L      &   7 May 1994  \\
SWP07406  &  1800  &  S      &  14 Dec. 1979  &  SWP52387  &  3600  &  L      &  12 Oct. 1994  \\
SWP08760  &  1800  &  S      &  14 Apr. 1980  &  SWP55055  &   900  &  L      &  21 Jun. 1995  \\
SWP09807  &  1440  &  L      &  23 May 1980  &  LWR02591  &  1200  &  S      &  13 Oct. 1978  \\
SWP10454  &  1440  &  L      &  23 Oct. 1980  &  LWR06389  &  3600  &  S      &  14 Dec. 1979  \\
SWP11004  &   900  &  L      &   9 Jan. 1981  &  LWR09130  &  2700  &  L      &  23 Oct. 1980  \\
SWP13975  &   900  &  L      &  10 May 1981  &  LWR10571  &   840  &  L      &  10 May 1981  \\
SWP15649  &   840  &  L      &   4 Dec. 1981  &  LWP09698  &  3000  &  L      &  12 Dec. 1986  \\
SWP15651  &  6600  &  L      &   4 Dec. 1981  &  LWP16684  &  1800  &  L      &  28 Oct. 1989  \\
SWP29862  & 10~800  &  L      &  12 Dec. 1986  &  LWP19253  &  1200  &  L      &  20 Nov. 1990  \\
SWP29863  &  1500  &  L      &  13 Dec. 1986  &  LWP21635  &  1200  &  L      &   4 Nov. 1991  \\
SWP37046  &  1800  &  L      &  16 Sep. 1989  &  LWP24280  &  1800  &  L      &   6 Nov. 1992  \\
SWP37420  &   600  &  L      &  21 Oct. 1989  &  LWP25995  &  3600  &  L      &  25 Jul. 1993  \\
SWP37476  &  1800  &  L      &  28 Oct. 1989  &  LWP28122  &  3900  &  L      &  13 May 1994  \\
SWP37477  & 11~160  &  L      &  28 Oct. 1989  &  LWP30936  &  1080  &  L      &  21 Jun. 1995  \\  \hline
\end{tabular}}
\par
\medskip
$^{*}$ L = Large aperture;  S = Small aperture.
\end{table}