\documentstyle[epsf,twoside]{article}

\input ibvs2.sty
\input ibvst.sty

\begin{document}

\IBVShead{4818}{21 December 1999}

\IBVStitletl{GSC 2684\_1255: A New Variable}{ in the Field of V454 Cygni }

\IBVSauth{\v{S}af\'{a}\v{r}, Jan}

\IBVSinsto{N. Copernicus Observatory, Krav\'{\i} hora 2, 616 00 Brno,
Czech Republic,\\ \indent e-mail: safarplanetar@email.cz}

\SIMBADobj{GSC 2684-1255}

\begintext

\IBVSTnam{GSC 2684\_1255}

\IBVSTcoo{20\hr15\mm55\fsec995}{+37\deg27\arcm15\farcs62}{2000.0}

\IBVSTobs{N. Copernicus Observatory and Planetarium, 0.4-m Newton telescope}

\IBVSTdet{CCD, SBIG ST7}

\IBVSTfil{Without filter}

\IBVSTcomp{GSC 3151\_2212}

\IBVSTchk{GSC 2684\_0631, GSC 3151\_2170}

\IBVSTsysn

\IBVSTtyp{ EW }

\IBVSTrem{
The variability of GSC 2684\_1255 was found while being used
as comparison star for variable V454 Cygni. CCD observations show
that the star exhibits light variations with an amplitude of 0.26
magnitude in the instrumental band (primary minimum), the secondary minimum is 0\fmm21 deep. Range of variability GSC 2684\_1255
is between 12.03 to 12.29 magnitude.\\
A period was computed by neural network software LANCELOT (Gaspani 1999).\\
The ephemeris is as follows:
$$\begin{array}{r@{}r@{}l}
{\rm Min~JD_{hel}} = 2451375.4528 & {} + 0\fday404194 & {} \times E.\\
                       \pm 0.0016 &      \pm 0.000068 \\
\end{array}$$
The shape of the observed light curve corresponds to those of W UMa type stars. Figure 1 shows the light curve of GSC 2684\_1255. Data were obtained from 18 Aug.\ 1999 to 31 Oct.\ 1999. The moments of light minima of the new variable star GSC 2684\_1255 are presented in Table 1.}

\begin{table}
\begin{center}
{\normalsize Table 1}
\vskip 2mm
\begin{tabular}{ccrrl}
\hline
Min JD hel & \raise-6pt\hbox{Uncertainty} & \multicolumn{1}{c}{\raise-6pt\hbox{$E$}} & \multicolumn{1}{c}{\raise-6pt\hbox{$O-C$}} & \raise-6pt\hbox{Observer} \\[-6pt]
2400000\,+ \\
\hline
51375.4528 & $\pm$0.0016 &   0.0 &    0.0000 & J. \v{S}af\'{a}\v{r} \\
51392.4321 & $\pm$0.0020 &  42.0 & $-$0.0032 & J. \v{S}af\'{a}\v{r} \\
51427.3936 & $\pm$0.0016 & 128.5 & $-$0.0019 & J. \v{S}af\'{a}\v{r} \\
51433.4575 & $\pm$0.0025 & 143.5 & $-$0.0029 & J. \v{S}af\'{a}\v{r} \\
51435.4751 & $\pm$0.0018 & 148.5 &    0.0004 & M. Zejda             \\
51449.4213 & $\pm$0.0029 & 183.0 & $-$0.0011 & J. \v{S}af\'{a}\v{r} \\
\hline
\end{tabular}
\end{center}
\end{table}

\IBVSTack{
Special thanks are due to Miloslav Zejda who observed this object on my
request.}

\IBVSfig{8cm}{4818-f1.ps}

\reference

Gaspani, A., 1999, LANCELOT software, private communication

\end{document}
