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\input ibvs2.sty

\begin{document}

\IBVShead{4503}{31 July 1997}

\IBVStitletl{PHOTOMETRY OF THE ECLIPSING BINARY V1481 C\lowercase{yg}}{ IN THE OPEN CLUSTER NGC\,7128}

\IBVSauth{Mamnun ZAKIROV}

\IBVSinsto{Astronomical Institute, Uzbek Academy of Sciences, e-mail: mamnun@astro.gov.uz}

\IBVSabs{New ephemeris and lightcurve characteristics are given for}
\IBVSabs{the eclipsing binary V1481 Cygni.}

\SIMBADobj{V1481 Cyg}
\SIMBADobj{NGC7128}
\IBVStyp{ EB/DM }
\IBVSkey{photometry}


\begintext

The variability of V1481 Cyg  (= HBV472;~ m=12.1 --- 12.6pg;~ Sp:B2V )
was discovered by Kohoutek (1972). The star lies in the center
of the  very compact $(D=3\farcs 2)$ young open cluster NGC\,7128.  There
are only  photographic (B,V,R) observations  of  the  variable  made  by
Alksnis (1973).  He determined the period of V1481 Cyg and it was
classified as an EB type eclipsing binary. The ephemeris for minima is:
$$
              Min I  =  JD2440040.61  +  2\fday 7634 \times E
$$

Our UBVR  photoelectric  observations  of  the  binary   were
carried out   with   1m   and   0.6m  telescopes  at  Mt.Maidanak
Observatory (Uzbekistan) in 1993--1995.  The star No. 2 of Hoag  et
al. (1961)  catalogue  was chosen as a comparison one $(V=10\,\fmm 13$,
$U-B=0\,\fmm 24$, $B-V=0\,\fmm 36$, $V-R=0\,\fmm 28)$. Total number of the measurements
are 126  in  U, 170  in B, 220 in V and 172 in R.  In accordance with our
estimation the probable error of a single observation of V1481 Cyg is
$0\,\fmm 05$ in $U$, $0\,\fmm 013$ in $B$, $0\,\fmm 008$ in $V$, $0\,\fmm 009$ in $R$.

Having used all times of brightness weakening we improved the ephemeris of
the binary by the method of least squares, as follows:

\begin{center}
\begin{tabular}{rcl}
 $Min I = JDH2440040.707$&+& 2\fday 763252 $\times~E$\\
$\pm$ 0.015&$\pm$& 0.000007\\
\end{tabular}
\end{center}


This ephemeris  was  used  to  calculate the O$-$C residuals in
Table 1.

\bigskip
\centerline{\figcap Table 1}
\vskip -4mm
\begin{center}
\begin{tabular}{|l|c|r|r|}
\hline
$Observers      $&$  JDH24... $&$E~~~$&$O-C$\\
\hline
$Alksnis,Za{\check c}s~(1981) $&$40731.470$&$   250$&$~-0\,\fday 050$\\
$             $&$40944.300$&$   327$&$+0.009$\\
$Kohoutek~(1972)$&$41151.489$&$   402$&$-0.045$\\
$             $&$41187.487$&$   415$&$+0.030$\\
$Alksnis,Za{\check c}s~(1981)$&$41259.293$&$   441$&$-0.008$\\
$             $&$41596.452$&$   563$&$~+0.034$\\
$             $&$41911.465$&$   677$&$+0.036$\\
$Present~paper$&$49170.442$&$  3304$&$-0.049$\\
$             $&$49173.266$&$  3305$&$+0.011$\\
$             $&$49579.447$&$  3452$&$-0.006$\\
$             $&$49582.246$&$  3453$&$+0.030$\\
\hline
\end{tabular}
\end{center}
\vfill \eject

\vspace{1mm}

\IBVSfig{12cm}{4503-f1.ps}{}

\smallskip

The U, B, V, R light  curves  are  shown  in Figure 1.  Their mean
characteristics are listed in Table 2.

\smallskip
\centerline{\figcap Table 2}
\vskip -4mm
\begin{center}
\begin{tabular}{|l|c|c|c|c|}
\hline
$Phase$&$V$&$U - B$&$B - V$&$V - R$\\
\hline
$Max   $&$12.14$&$0.11$&$0.86$&$0.73$\\
$Min I $&$12.55$&$0.07$&$0.89$&$0.74$\\
$Min II$&$12.54$&$0.04$&$0.89$&$0.75$\\
\hline
\end{tabular}
\end{center}

\bigskip

\references

Alksnis, A., 1973, {\it Astron. Tsir.}, No.\,761, p.7

Alksnis, A., Za\v{c}s, L., 1981, {\it Peremen. Zvezdy}, {\bf 21}, 499

Hoag, A.A. {\it et al.\/}, 1961, {\it Publ. Naval. Obs.}, XVII, Part VII, 439

Kohoutek, L., 1972, {\it IBVS}, No.\,683

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