\begin{table}%t1
\caption{Log of observations.\label{table:observations}}
%\centerline
$$
{\begin{tabular} {llcrcrl}
\hline\hline
Epoch        & Instrument & Image ID & Date & $\lambda$ Range & 
                                                  $t_{\rm exp}$ & Remarks
                                                     \rule[-1mm]{0mm}{4.5mm}\\
             &            &      & dd/mm/yy &  [\AA]     &  [min] &          
                                                     \rule[-2mm]{0mm}{4.5mm}\\
\hline %----------------------------------------------------------------
{1983.3} & IUE SWP    & 19905 & 05/05/83 & 1152--1978 & 183 \\
\hline %----------------------------------------------------------------
{1986.3} & IUE SWP    & 28211 & 23/04/86 & 1152--1978 &  45 & 
                                                               underexposed \\
             & IUE LWP    & 08083 & 23/04/86 & 1853--3347 & 240 \\
\hline %----------------------------------------------------------------
{1990.6} & CTIO 4m (a)&       & 12/08/90 & 3447--5096  &   8 &
                                       1.6\arcsec\  slit; $\times$1.3 assumed \\
\hline %----------------------------------------------------------------
{1993.9} & IUE SWP    & 49112 & 05/11/93 & 1152--1978 & 180 
                                                & SWP49075: no useful data \\
             & CTIO 4m (b)&   & 28/01/94 & 3130--7410  & 2 &
                                 1.33\arcsec\  slit; $\times$1.3 to match IUE \\
\hline %----------------------------------------------------------------
{1994.7} & CTIO 4m (b)&   & 02/08/94 & 3108--7375 & 10 &  
                                   2\arcsec\  slit, 40\% flux lost, not used \\
             & CTIO 4m (b)&   & 02/08/94 & 3108--7375 &  5 & 
                                   10\arcsec\  slit, $\times$1.5 to match IUE  \\
             & IUE SWP    & 52212 & 25/09/94 & 1152--1978 & 180 & 
                                                       saturated: not used \\
             & IUE SWP    & 52222 & 26/09/94 & 1152--1978 & 60  & 
 \raisebox{-1.5ex}[0pt][0pt]{\Large \}} \raisebox{-1.2ex}[0pt][0pt]{weighted 
                                                           mean used} \\
             & IUE SWP    & 52223 & 27/09/94 & 1152--1978 & 90 \\
\hline %----------------------------------------------------------------
{1995.0} & CTIO 4m (c)& & 31/12/94 & 3184--7463  & 10 &  
                                    2\arcsec\  slit; not used (40\% flux lost) \\
             & CTIO 4m (c)& & 31/12/94 & 3184--7463  &  5 &  
                                   10\arcsec\  slit; $\times$1.2 to match IUE \\
             & IUE SWP    & 53255 & 02/01/95 & 1152--1978 &  60 & 
 \raisebox{-1.5ex}[0pt][0pt]{\Large \}} \raisebox{-1.2ex}[0pt][0pt]
                                                        {weighted mean used} \\
             & IUE SWP    & 53256 & 02/01/95 & 1152--1978 &  90 \\
\hline %----------------------------------------------------------------
{ 1995.3} & IUE SWP    & 54312 & 06/04/95 & 1152--1978 & 180 &
                                       exposure segmented $2\times90$~min (g)\\
\hline %----------------------------------------------------------------
{ 1995.7} & CTIO 4m (d)&       & 24/08/95 & 3350--6737 & 10
                                 & 1.5\arcsec\  slit, $\times$1.9 to match IUE \\
             & IUE SWP    & 55790 & 01/09/95 & 1152--1978 & 90 & 
                                                               weakly exposed\\
\hline %----------------------------------------------------------------
{ 1995.9} & IUE SWP    & 56155 & 06/11/95&1152--1978&  120 \\
             & CTIO 1.5m (e)&     & 16/11/95&3096--6534&   15 & 
                                    2\arcsec\  slit, $\times$1.3 to match IUE \\
\hline %----------------------------------------------------------------
{ 1996.0} & HST FOS G130H &Y31L0105T& 11/12/95& 1087--1605 & 190 & \\
             & HST FOS G190H &Y31L0106T& 11/12/95& 1573--2330 &  43 & \\
             & HST FOS G400H &Y31L0107T& 11/12/95& 3239--4821 &  35 & \\
             & CTIO-4m (d)&       & 22/01/96& 3633--7330 & 10 & 
                              flux 15\% lower than next obs.; not used\\
             & CTIO-4m (d)&       & 24/01/96& 3633--7330 &  10 & \\
             & IUE SWP    & 56787 & 10/02/96& 1152--1978 & 120 & not used \\
\hline %----------------------------------------------------------------
{ 1996.9} & HST FOS G130H &Y3J30106T& 12/11/96& 1087--1605 & 63.2 \\
             & HST FOS G130H &Y3J30107T& 12/11/96& 1087--1605 & 63.2 &
                            \raisebox{0ex}[0pt][0pt]{\Large \}} mean used \\ 
             & HST FOS G130H &Y3J30108T& 13/11/96& 1087--1605 & 63.2 \\
             & HST FOS G190H &Y3J30109T& 13/11/96& 1573--2330 & 43 & \\
             & HST FOS G400H &Y3J3010AT& 13/11/96& 3239--4821 & 15 & \\
             & CTIO 4m (d)   &         & 13/01/97& 3680--7390 & 30 & \\
\hline %----------------------------------------------------------------
{ 1999.0} & HST STIS G140L&o55r01010& 08/01/99& 1124--1730 & 75 & 
                                                              {\sc fuv-mama} \\
             & HST STIS G230L&o55r01020& 08/01/99& 1580--3160 & 48 & 
                                                              {\sc nuv-mama} \\
             & HST STIS G430L&o55r01030& 08/01/99& 2900--5710 & 28 & {\sc ccd}\\
             & HST STIS G750L&o55r02020& 08/01/99&~~5236--10266& 38 &{\sc ccd}\\
\hline %----------------------------------------------------------------
{ 2000.1} & HST STIS G140L&o5im01010&04/02/00&1120--1718 &100 & 
                                                              {\sc fuv-mama} \\
             & HST STIS G230L&o5im01020&04/02/00&1580--3165 & 61 & 
                                                              {\sc nuv-mama} \\
             & HST STIS G430L&o5im02010&04/02/00&2900--5712 & 34 & {\sc ccd}\\
             & ESO 3.6-m (f)  &         &05/03/00&3229--8063 & 30 \\
\hline %----------------------------------------------------------------
\end{tabular}}
$$
\par
(a) CTIO 4m, RC spectrograph, grating KPGL2, CCD detector.  \rule[0mm]{0mm}{4.5mm}\\
(b) CTIO 4m, RC spectrograph, grating KPGL2, Ret1 detector. \\
(c) CTIO 4m, RC spectrograph, grating KPGL2, Ret2 detector. \\
(d) CTIO 4m, RC spectrograph, grating KPGL3, Loreal3K-1 detector. \\
(e) CTIO 1.5m, RC spectrograph, Loral1K-1 detector. \\
(f) ESO 3.6-m with EFOSC/2.9. \\
(g) {\sc ines} and {\sc newsips} IUE archives erroneously assume one single
90~min exposure and hence give wrongly calibrated data. \\
\end{table}