%\documentclass[referee]{aa}     % for a referee version
\documentclass{aa}     

\begin{document}
 
   \thesaurus{07         % A&A 
              (08.01.2;  % stars: activity
               08.06.1;  % stars: flare
               08.12.1;  % stars: late type 
               08.16.3;  % stars: population II
               08.16.5;  % stars: pre-main sequence
               08.22.3)} % stars: variables

\title{Long-term monitoring of active stars}
\subtitle{VIII. UBV(RI)$_c$ photometry collected in February 1992} 

\author{G. Cutispoto \inst{1}} 
 
\institute{Osservatorio Astrofisico di Catania, V.le A.Doria 6, 
I-95125 Catania, Italy; \\
e-mail:~~gcutispoto@alpha4.ct.astro.it}

\maketitle

\begin{abstract}
As a part of an extensive program focusing on the global properties and 
evolution of active stars, high-precision {\it UBV(RI)$_c$} photometry of 31
selected stars, collected at the European Southern Observatory over the 
14-29 February 1992 interval, is presented. Significant evolution of the light 
curves, period variations and evidence for long-term variability of the global 
degree of spottedness are found. Some spectral classifications are 
revised and the inferred photometric parallaxes are compared, whenever
possible, with the values measured by the Hipparcos satellite. Flare events 
were detected for the star \object{HD 16157} = CC Eri, EXO 055609-3804.4 = 
\object{TY Col} and \object{HD 119285} = V851 Cen. Optical variability was 
discovered for the Pop II binary \object{HD 89499}. These observations 
contribute to the establishment of a 
time-extended photometric database which can give important clues on topics 
such as the stability of spotted areas, differential rotation, solar-like 
cycles and the correlation between inhomogeneities at different atmospheric 
levels.
%
\keywords{stars: activity -- stars: flare -- stars: late-type -- stars: 
variables -- stars: population II -- stars: pre-main sequence}
\end{abstract}

\newpage
\begin{table*}
\caption{Comparison (c) and check (ck) stars for each program star (v),
standard deviations ($\sigma$) for the v-c and ck-c 
{\it V}-band differential magnitudes for each series of N nights, peak-to-peak
($\Delta V$) amplitude of the {\it V}-band light curve and period (P) of
variability}
\begin{tabular}{|ll|l|l|c|c|c|c|l|}
\hline
\multicolumn{2}{|c}{Program star} & \multicolumn{1}{|c}{(c)} & 
\multicolumn{1}{|c|}{(ck)} & $\sigma$ & $\sigma$ & N & 
$\Delta V$ & \multicolumn{1}{c|}{P} \\
\multicolumn{2}{|c|}{(v)} & & & (v-c) & (ck-c) &  & (mag.) & 
\multicolumn{1}{|c|}{(days)} \\
\hline
HD 16157     & = CC Eri    & \object{HD 16371}  & \object{HD 16591}  
& 25 & 5 & 10 &.06&1.56145\\
HD 17084     & = UX For    & \object{HD 16975}  & \object{HD 17322}  
& 12 & 6 &  8 &.04&0.957  \\
HD 26354     & = AG Dor    & \object{HD 26779}  & \object{HD 27274}  
& 11 & 4 &  9 &.04&2.533  \\
HD 32918     & = YY Men    & \object{HD 33763}  & \object{HD 33747}  
& 47 & 6 & 15 &.13&9.75   \\
1E 0505-0527 & = EZ Eri    & \object{HD 33725}  & \object{HD 34673}  
& 23 & 4 & 13 &.08&9.08   \\
HD 293857    &             & \object{HD 33725}  & \object{HD 34673}  
&  4 & 4 & 10 &.01&--     \\
HD 34802     & = YZ Men    & \object{HD 34297}  & \object{HD 33563}  
& 50 & 4 & 15 &.16&19.310 \\
EXO 0527-3329& = UX Col    & \object{SAO 195800}& \object{HD 35528}  
& 15 & 4 & 13 &.05&2.29   \\
HD 36705     & = AB Dor    & \object{HD 35230}  & \object{HD 36316}  
& 28 & 5 & 12 &.09&0.51479\\
EXO 0532-0510& = V~1321 Ori& \object{HD 36235}  & \object{HD 36003}  
&111 & 4 & 13 &.32&5.6    \\
HD 39917     & = SZ Pic    & \object{HD 39901}  & \object{HD 39962}  
& 41 & 5 & 11 &.11&4.905  \\
EXO 0556-3804& = TY Col    & \object{HD 40865}  & \object{HD 39601}  
& 32 & 6 & 13 &.10&3.62   \\
HD 61245     & = V~344 Pup & \object{HD 61390}  & \object{HD 62061}  
& 21 & 3 & 12 &.08&11.761 \\
HD 81410     & = IL Hya    & \object{HD 81904}  & \object{HD 80991}  
& 75 & 5 & 15 &.22&12.86833\\
HD 82558     & = LQ Hya    & \object{HD 82508}  & \object{HD 82447}  
& 36 & 4 & 14 &.12&1.61   \\
HD 86005     & = LZ Vel    & \object{HD 86034}  & \object{HD 85849}  
& 15 & 3 &  9 &.04&44.57  \\
HD 89499     &             & \object{HD 88351}  & \object{HD 91682}  
&  9 & 5 & 13 &.03&5.574  \\
HD 98712     & = SZ Crt    & \object{HD 97977}  & \object{HD 98251}  
&  8 & 8 & 12 &.03&11.58  \\
SAO 202618   & = V~858 Cen & \object{HD 100912} & \object{HD 101679} 
& 49 & 5 & 14 &.15&1.04303\\
HD 101309    & = V~829 Cen & \object{HD 101679} & \object{HD 101614} 
& 30 & 5 & 15 &.09&11.65  \\
HD 102077    & = V~838 Cen & \object{HD 102076} & \object{HD 102202} 
& 12 & 3 &  9 &.04&1.848  \\
HD 106225    & = HU Vir    & \object{HD 105796} & \object{HD 106270} 
& 57 & 3 & 15 &.18&10.424 \\
HD 116544    & = IN Vir    & \object{HD 117635} & \object{HD 118330} 
& 69 & 4 & 15 &.21&8.40   \\
HD 119285    & = V~851 Cen & \object{HD 119164} & \object{HD 119076} 
&  5 & 5 & 13 &.02&12.05  \\
HD 127535    & = V~841 Cen & \object{HD 128227} & \object{HD 128618} 
& 40 & 5 & 13 &.12&5.929  \\
HD 136905    & = GX Lib    & \object{HD 136480} & \object{HD 137241} 
& 32 & 3 & 12 &.12&11.134 \\
HD 139084    & = V~343 Nor & \object{HD 139070} & \object{HD 138363} 
& 71 & 3 & 14 &.19&4.32   \\
SAO 121177   &             & \object{HD 141272} & \object{HD 140345} 
&  4 & 7 &  2 &.01&--     \\
HD 154338    & = V~991 Sco & \object{HD 326583} & \object{HD 154312} 
& 16 & 7 & 10 &.05&3.27   \\
HD 155555    & = V~824 Ara & \object{HD 156427} & \object{HD 154577} 
& 11 & 7 & 10 &.04&1.71   \\
HD 158394/5  & = V~1017 Sco& \object{HD 157750} & \object{HD 158619} 
&  2 & 3 &  9 &.01&--     \\
\hline
\end{tabular}
\end{table*}

\newpage
\begin{table}
\caption{Mean atmospheric extinction coefficients for La Silla site, 
obtained over the 14-29 February 1992 period}
\begin{tabular}{|c|c|c|c|c|c|}
\hline
            &  U  &  B  &  V  &  R  &  I  \\
\hline
Mag/airmass &.538 &.308 &.203 &.165 &.118 \\
\hline
\end{tabular}
\end{table}

\newpage
\begin{table*}
\caption{{\it V} magnitude and colors for the c and ck stars derived from
standard stars. Errors are of the order of 0.01 magnitudes. The symbol ":" 
denotes errors of the order of 0.02 magnitudes}
\renewcommand{\arraystretch}{.9}
\begin{tabular}{|l|c|l|c|c|c||l|c|l|c|c|c|}
\hline
\multicolumn{1}{|c|}{c or ck} & {\it V} & 
\multicolumn{1}{|c|}{{\it U-B}} & {\it B-V} &{\it V-R}$_c$ &{\it V-I}$_c$~ &
\multicolumn{1}{|c|}{c or ck} & {\it V} & 
\multicolumn{1}{|c|}{{\it U-B}} & {\it B-V} &{\it V-R}$_c$ &{\it V-I}$_c$~ \\
\hline
HD 16371  &8.09&0.55:&0.90&0.48&0.93& HD 88351  &6.59&0.54:&0.92&0.50&0.97 \\
HD 16591  &7.22&0.67:&0.94&0.51&0.96& HD 91682  &8.51&0.26:&0.69&0.39&0.73 \\
HD 16975  &5.98&0.65 &0.92&0.47&0.90& HD 97977  &8.84&1.63:&1.42&0.75&1.43 \\
HD 17322  &7.63&0.04 &0.58&0.33&0.65& HD 98251  &9.20&1.44:&1.30&0.69&1.30 \\
HD 26779  &8.58&1.26:&1.23&0.64&1.20& HD 100912 &8.63&0.43 &0.93&0.51&1.00 \\
HD 27274  &7.64&1.11:&1.12&0.69&1.23& HD 101614 &6.85&0.00:&0.58&0.34&0.65 \\
HD 33563  &7.54&-.04:&0.48&0.30&0.59& HD 101679 &8.11&0.79:&1.09&0.59&1.14 \\
HD 33725  &8.04&0.42 &0.80&0.44&0.84& HD 102076 &7.11&0.77 &1.01&0.52&0.98 \\
HD 33747  &8.75&0.72:&0.99&0.52&1.01& HD 102202 &8.86&0.19 &0.68&0.39&0.73 \\
HD 33763  &8.37&0.50:&0.89&0.49&0.94& HD 105796 &8.06&0.94:&1.07&0.55&1.03 \\
HD 34297  &7.33&0.07:&0.65&0.38&0.74& HD 106270 &7.58&0.29:&0.74&0.40&0.76 \\
HD 34673  &7.77&0.91 &1.04&0.63&1.21& HD 117635 &7.32&0.32:&0.78&0.46&0.86 \\
HD 35230  &7.58&0.47 &0.88&0.48&0.93& HD 118330 &7.04&-.01:&0.53&0.32&0.61 \\
HD 35528  &6.81&0.89:&1.06&0.53&0.99& HD 119076 &6.87&0.87 &1.16&0.60&1.14 \\
SAO 195800&9.18&0.36:&0.85&0.47&0.91& HD 119164 &7.20&1.14 &1.28&0.64&1.22 \\
HD 36003  &7.64&1.13:&1.13&0.69&1.25& HD 128227 &8.33&0.81 &1.07&0.57&1.10 \\
HD 36235  &9.43&-.04:&0.52&0.31&0.61& HD 128618 &8.03&1.61:&1.46&0.77&1.47 \\
HD 36316  &7.95&1.74:&1.46&0.78&1.51& HD 136480 &7.35&1.11 &1.16&0.60&1.15 \\
HD 39601  &8.18&0.28:&0.78&0.44&0.86& HD 137241 &7.35&1.09 &1.14&0.58&1.10 \\
HD 39901  &6.55&1.62:&1.36&0.71&1.32& HD 138363 &7.12&0.94 &1.13&0.61&1.15 \\
HD 40865  &8.64&0.05:&0.61&0.37&0.71& HD 139070 &8.70&0.80 &1.11&0.60&1.15 \\
HD 61390  &7.92&0.72 &1.01&0.53&1.03& HD 140345 &8.18&0.11:&0.63&0.35&0.68 \\
HD 62061  &7.51&0.08 &0.60&0.33&0.65& HD 151272 &7.44&0.41:&0.81&0.45&0.84 \\
HD 80991  &8.51&0.83:&1.04&0.54&1.02& HD 326583 &9.52&0.10:&0.63&0.35&0.69 \\
HD 81904  &8.02&0.72:&0.98&0.51&0.98& HD 154312 &7.98&0.02:&0.53&0.31&0.61 \\
HD 82477  &6.11&1.18 &1.19&0.61&1.17& HD 154577 &7.40&0.56:&0.88&0.53&0.99 \\
HD 82508  &7.58&0.35 &0.71&0.40&0.80& HD 156427 &7.41&1.69:&1.49&0.81&1.55 \\
HD 85849  &8.52&1.06:&1.14&0.58&1.11& HD 157750 &8.03&0.17:&0.67&0.37&0.70 \\
HD 86034  &7.90&1.33:&1.26&0.63&1.20& HD 158619 &6.41&1.26:&1.19&0.60&1.11 \\
\hline
\end{tabular}
\end{table*}

\newpage
\begin{table*}
\caption{Maximum luminosity ({\it V$_m$}) and corresponding colors measured
for the program stars, inferred spectral classification (Spectral Type),
distance range measured by the Hipparcos satellite (D$_H$), photometric
distance inferred from the adopted spectral classification (d$_{ph}$) and
{\it V}-band maximum luminosity ever observed ({\it V$_{max}$})}
\renewcommand{\arraystretch}{1.05}
\small
\begin{tabular}{|ll|r|l|l|l|l|l|l|l|r|}
\hline
\multicolumn{2}{|c|}{Program Star} & \multicolumn{1}{|c|}{${\it V}_{m}$} & 
\multicolumn{1}{|c|}{{\it U-B~}} & \multicolumn{1}{|c|}{{\it B-V~}} & 
\multicolumn{1}{|c|}{{\it V-R}$_c$} & \multicolumn{1}{|c|}{{\it V-I}$_c$~} & 
\multicolumn{1}{c|}{Spectral Type} & \multicolumn{1}{|c|}{D$_H$} &
\multicolumn{1}{c|}{d$_{ph}$} & \multicolumn{1}{|c|}{${\it V}_{max}$} \\
\hline
HD 16157   & = CC Eri   & 8.81 & 1.10 & 1.36 & 0.88 & 1.86 & K7~V + M3~V   &
11.4 - 11.6 & 11.5 &  8.70 \\
HD 17084   & = UX For   & 8.05 & 0.23 & 0.75 & 0.44 & 0.89 & G6~V + K3~V   &
39 - 42     & 39   &  7.95 \\
HD 26354   & = AG Dor   & 8.55 & 0.63 & 0.91 & 0.54 & 1.03 & K1~V + K5~V   &
34 - 36     & 35   &  8.55 \\
HD 32918   & = YY Men   & 7.99 & 0.69 & 1.06 & 0.59 & 1.14 & K1~III        &
247 - 355   & 219  &  7.93 \\
1E 0505-0527&= EZ Eri   &10.21 & 0.51 & 0.92 & 0.51 & 1.01 & K2~IV + G2~V  &
            & 290  & 10.17 \\
HD 293857  &            & 9.26 & 0.21 & 0.72 & 0.42 & 0.82 & G6-G9~V       &
31 - 213    & 52-63&  9.26 \\
HD 34802   & = YZ Men   & 7.70 & 0.82 & 1.07 & 0.61 & 1.16 & K1~III        &
162 - 201   & 185  &  7.52 \\
EXO 0527-3329&= UX Col  &10.55 & 0.80 & 1.07 & 0.64 & 1.23 & K3/5 PMS      &
            & $>$43& 10.53 \\
HD 36705   & = AB Dor   & 6.84 & 0.39 & 0.83 & 0.49 & 0.96 & K0~V          &
14.8 - 15.1 & 14.9 &  6.75 \\
EXO 0532-0510&= V1321 Ori&10.51& 0.80 & 1.24 & 0.73 & 1.42 & K3 wTTS       &
            & 500  & 10.51 \\
HD 39917   & = SZ Pic   & 7.85 & 0.31 & 0.81 & 0.47 &0.91&K0~IV/III + G3~IV/III&
172 - 224   & 190  &  7.81 \\
EXO 0556-3804&= TY Col  & 9.56 & 0.16 & 0.68 & 0.42 & 0.82 & G5~V (PMS ?)  &
            & $>$83&  9.53 \\
HD 61245   & = V344 Pup & 6.86 & 0.82 & 1.04 & 0.56 & 1.05 & K1~IV/III     &
105 - 119   & 102  &  6.85 \\
HD 81410   & = IL Hya   & 7.28 & 0.73 & 1.02 & 0.57 & 1.08 & K1~III/IV + ? &
108 - 133   & 119  &  7.20 \\
HD 82558   & = LQ Hya   & 7.80 & 0.57 & 0.90 & 0.53 & 1.02 & K2~V          &
18.0 - 18.7 & 18.5 &  7.77 \\
HD 86005   & = LZ Vel   & 7.19 & 0.99 & 1.31 & 0.70 &1.34&K4~III/II + K1~III/II&
$\geq$~650& $\geq$~315 & 7.18 \\
HD 89499   &            & 8.70 & -.04 & 0.73 & 0.47 & 0.95 & G-K IV ?      &
104 - 122   & 101-165&8.60 \\
HD 98712   & = SZ Crt   & 8.61 & 1.16 & 1.33 & 0.84 & 1.67 & K7~V + M2/3~V &
12.9 - 13.5 & 12.3 &  8.59 \\
SAO 202618 & = V858 Cen &10.50 & 0.53 & 0.90 & 0.54 & 1.05 & K1~V/IV + M5:V&
            & 94   & 10.50 \\
HD 101309  & = V829 Cen & 7.86 & 0.47 & 0.93 & 0.54 & 1.05 & K1~IV + G5~V  &
110 - 135   & 127  &  7.82 \\
HD 102077  & = V838 Cen & 8.95 & 0.55 & 0.92 & 0.56 & 1.08 & K0/1~V + K5~V &
44 - 55     & 42   &  8.85 \\
HD 106225  & = HU Vir   & 8.69 & 0.62 & 1.00 & 0.58 & 1.14 & K1~IV + ?     &
108 - 148   & 170  &  8.55 \\
HD 116544  & = IN Vir   & 9.08 & 1.04 & 1.16 & 0.65 & 1.22 & K3/4~IV/V     &
97 - 136    & 89   &  9.08 \\
HD 119285  & = V851 Cen & 7.68 & 0.80 & 1.07 & 0.61 & 1.20 & K3~IV/V       &
69 - 85     & 45   &  7.62 \\
HD 127535  & = V841 Cen & 8.50 & 0.81 & 1.08 & 0.61 & 1.18 & K3~IV/V       &
30 - 55     & 65   &  8.41 \\
HD 136905  & = GX Lib   & 7.30 & 0.72 & 1.03 & 0.57 & 1.10 & K2~IV + ?     &
87 - 105    & 105  &  7.27 \\
HD 139084  & = V343 Nor & 7.99 & 0.36 & 0.81 & 0.47 & 0.91 & K0~PMS        &
38 - 42     & $>$26&  7.98 \\
SAO 121177 &            & 9.15 & 0.40 & 0.84 & 0.50 & 0.96 & G9/K0~V + K7~V&
45 - 52     & 48   &  9.11 \\
HD 154338  & = V991 Sco & 9.69 & 0.19 & 0.68 & 0.39 & 0.76 & G4/5~PMS      &
$>$27       & $>$91&  9.67 \\
HD 155555  & = V825 Ara & 6.83 & 0.36 & 0.81 & 0.48 & 0.91 &G7~PMS + K0~PMS&
30.7 - 32.2 & 33   &  6.63 \\
HD 158394/5& = V1017 Sco& 8.38 & 0.42 & 0.83 & 0.59 & 1.22 & K3~III + A5~V &
207 - 402   & 358  &  8.23 \\
\hline
\end{tabular}
\end{table*}
\end{document}
