\documentstyle[twoside, ibvs2, ibvst, epsf]{article} 
\begin{document}

\IBVShead{5024}{26 January 2001}

\IBVStitle{GSC 3969.2430 L\lowercase{ac}: A new short period eclipsing binary}
\centerline{(BAV MITTEILUNGEN NO. 135)}
\IBVSauth{Agerer, Franz}

\IBVSinsto{Bundesdeutsche Arbeitsge\-mein\-schaft f\"{u}r Ver\"{a}nderliche
Sterne e.V. (BAV), Munsterdamm 90, D--12169~Berlin,\\ \indent Germany, e-mail: agerer.zweik@t-online.de}

\SIMBADobj{GSC 3969-2430}

\begintext

\IBVSTnam{GSC 3969.2430}

\IBVSTcoo{22\hr09\mm37\fsec5}{52\deg34\arcm16\arcs}{2000}

\IBVSTobs{Private observatory, 20-cm SCT}

\IBVSTdet{SBIG ST6 camera}

\IBVSTfil{None}

\IBVSTcomp{GSC 3969.2314}

\IBVSTchk{GSC 3969.2134, GSC 3969.2994, GSC 3969.2152}

\IBVSTsysn

\IBVSTdata{Upon request}

\IBVSTtyp{ EW }

\IBVSTrem{
In a photometric investigation in the field of IU Lac, GSC 3969.2430
showed to be variable. A check of the GCVS (Kholopov 1985) and NSV
catalog (Kukarkin et al.\ 1982) did not reveal any previously known
variable at this position. The brightness of GSC 3969.2430 is given as
12\fmm56. Observations were performed in 6 nights between August and
December 2000. The primary and secondary minima have an amplitude of
0\fmm22 and 0\fmm19 respectively. The minimum times are calculated
according to the Kwee--van Woerden method (Kwee, van Woerden 1956). A
least squares fit to the data given in Table~1 (weighting half those
assigned by colon) led to the preliminary
ephemeris:\belowdisplayskip-12pt
\begin{equation}
\begin{array}{r@{}r@{}l}
{\rm Min~I = HJD~}2451817.5495 & {} + 0\fday308894 & {} \times E. \\ 
 \pm 2 & \pm 5 \\ 
\end{array}
\end{equation}
}

\IBVSTack{
This research made use of the SIMBAD data base, operated by the CDS 
at Strasbourg, France.}

\begin{table}[t]
\caption{Observed times of minima for GSC~3969.2430, epochs and residuals
 computed with respect to the linear ephemeris derived in this paper}
\begin{center}
\begin{tabular}{r@{.}lcr@{.}lr@{.}lc|r@{.}lcr@{.}lr@{.}lc}
\hline
 \multicolumn{2}{c}{HJD} & \lower6pt\hbox{Type$^*$} &
 \multicolumn{2}{c}{\lower6pt\hbox{Epoch}} &
 \multicolumn{2}{l}{\lower6pt\hbox{$O-C$}} & &
 \multicolumn{2}{c}{HJD} & \lower6pt\hbox{Type$^*$} &
 \multicolumn{2}{c}{\lower6pt\hbox{Epoch}} &
 \multicolumn{2}{l}{\lower6pt\hbox{$O-C$}} & \\[-4pt]
 \multicolumn{2}{c}{2400000\,+} & &
 \multicolumn{2}{c}{} &
 \multicolumn{2}{l}{} & &
 \multicolumn{2}{c}{2400000\,+}\\
\hline
51771 & 3699& s &$ -150$& 5 &$ +0$& 0001 &&51817 & 5489& p & $ 0$& $0$ & $-0$& 0006 \\
51771 & 5226& p &$ -149$& 0 &$ -0$& 0017 &&51838 & 5548& p & $ 68$& $0$ & $+0$& 0005 \\
51816 & 314: & p &$ -4$& 0 &$ +0$& 000: &&51839 & 3283& s & $ 70$& $5$ & $+0$& 0018 \\
51816 & 4691& s &$ -4$& 5 &$ +0$& 0007 &&51839 & 4831& p & $ 71$& $0$ & $+0$& 0021 \\
51816 & 6221& p &$ -3$& 0 &$ -0$& 0007 &&51890 & 289: & s & $ 235$& $5$ & $-0$& 005: \\
\hline
\multicolumn{16}{c}{\normalsize $^*$\ `p' and `s' denote primary and secondary minima,
 respectivelty} \\
\end{tabular}
\end{center}
\end{table}

\IBVSfig{7.5cm}{5024-f1.eps}{Differential light curve of GSC 3969.2430}

\references

Kholopov, P. N. et al., 1985, {\it General Catalogue of Variable Stars},
4th Edition, Nauka, Moscow

Kukarkin, B. et al., 1982, {\it NSV Catalogue}, Nauka, Moscow

Kwee, K. K., van Woerden, H., 1956, {\it Bull.~Astr.~Inst.~Netherlands}, {\bf 12}, No.\ 464, 327

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