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\begin{document}

\IBVShead{4986}{16 November 2000}

\IBVStitle{UY Piscium: 1990--1992} 

\IBVSauth{Zsoldos, E.}

\IBVSinsto{Konkoly Observatory, Budapest, P.O.Box 67, 1525 Hungary, email: zsoldos@konkoly.hu}

\SIMBADobj{UY Psc}
\IBVStyp{ SR }
\IBVSkey{variable stars - photometry}
\IBVSabs{Photometry of UY Psc is presented.}

\begintext

The variability of UY Piscium was discovered by Strohmeier (Strohmeier et 
al.\ 1957). Huth (1959) detected 100--150 days long cycles from 
photographic plates. The spectral type of the star was estimated as 
M0 (Vyssotsky \& Balz 1958) or K (G\"otz \& Wenzel 1962). Its luminosity 
class is unknown. The only photoelectric photometry of the variable 
was published by Eggen (1973), who estimated a period of about 80 days 
from his observations. The star is classified as SRD in the {\sl 
General Catalogue of Variable Stars}.

I observed UY Psc in 1990--1992 in Budapest with the 24-inch telescope 
of Konkoly Observatory. The observing circumstances were the same as 
mentioned in previous papers (Zsoldos 1993, 1995). I used HD 7346 as a 
comparison star ($V = 8.500$, $B-V = 1.093$) (Ochsenbein et al.\ 2000) and 
HD 7529 as a check. The observations are given in Table~1 and Fig.~1.

\begin{table}[h]
\caption{Photometry of UY Piscium}
\begin{center}
\begin{tabular}{rcc}
\hline
\multicolumn1c{J.D.} & $V$ & $B-V$ \\
\hline
2448163.477 & 9.099 & 1.697 \\
  48176.428 & 9.098 & 1.719 \\
  48187.404 & 9.043 & 1.692 \\
  48190.386 & 9.036 & 1.735 \\
  48202.371 & 8.971 & 1.733 \\
  48271.245 & 8.990 & 1.803 \\
  48480.540 & 8.905 & 1.747 \\
  48485.556 & 8.916 & 1.761 \\
  48502.497 & 8.914 & 1.749 \\
  48506.508 & 8.944 & 1.780 \\
  48534.474 & 9.023 & 1.780 \\
  48536.451 & 9.028 & 1.747 \\
  48561.389 & 9.072 & 1.777 \\
  48562.371 & 9.077 & 1.765 \\
  48593.304 & 9.096 & 1.754 \\
2448897.438 & 8.941 & 1.832 \\
\hline
\end{tabular}
\end{center}
\end{table}

Figure 1 shows the light curve of UY Psc (including Eggen's observations, 
too) phased with a period of 133\fday8. This is longer than the estimate 
by Eggen but is in agreement with that of Huth. The amplitude seems to be 
variable, it was certainly larger when Eggen observed the star. 
The $B-V$ colour (not shown in Fig.~1) does not show any variation 
correlated with the light curve.

\IBVSfig{11.85cm}{4986-f1.ps}{The light curve of UY Piscium. The dots are 
from Table 1, the circles are Eggen's observations.}

The star does not seem to be a SRD variable. Its colour index is too red, 
more appropriate to an M than a K star as given in the {\sl GCVS}. The 
late spectral type and the small amplitude indicates that a classification 
of SRA might be more appropriate.

This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France.

\references

Eggen, O. J., 1973, {\it PASP}, {\bf 85}, 42

G\"otz, W., Wenzel, W., 1962, {\it Mitt.\ Ver.\ Sterne}, No.\ 628

Huth, H., 1959, {\it Mitt.\ Ver.\ Sterne}, No.\ 421

Ochsenbein, F., Bauer, P., Marcout, J., 2000, {\it A\&AS}, {\bf 143}, 23

Strohmeier, W., Kippenhahn, R., Geyer, E., 1957, {\it Kleine Ver\"off.\ Remeis-Sternw.\ Bamberg}, No.\ 18

Vyssotsky, A. N., Balz, A. G. A., Jr., 1958, {\it Publ.\ Leander-McCormick Obs.},
{\bf 13}, Part II

Zsoldos, E., 1993, {\it A\&A}, {\bf 280}, 177

Zsoldos, E., 1995, {\it A\&A}, {\bf 296}, 122

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