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\input ibvs2.sty
\input ibvst.sty

\begin{document}

\IBVShead{5142}{24 July 2001}

\IBVStitle{Photoelectric Observations of DR Vulpeculae}

\IBVSauth{\c{C}\.{i}\c{c}ek, C.}

\IBVSinsto{\c{C}anakkale Onsekiz Mart University, Faculty of Arts and
Sciences, Department of Physics,\\ \indent
 TR-17100 \c{C}anakkale, Turkey, email: canerk@bornova.ege.edu.tr}

\SIMBADobjAlias{HD 339770}{BD+26 3835}

\begintext

\IBVSTnam{DR Vul = DM +26\deg 3835 = HD 339770}

\IBVSTcoo{20\hr13\mm46\fsec85}{+26\deg45\arcm01\farcs59}{2000}

\IBVSTobs{Ege University Observatory (EUO), 48-cm Cassegrain
reflector; T\"{U}B\.{I}TAK (Scientific and Technical Research
Council of Turkey) National Observatory (TNO), 40-cm Cassegrain
telescope}

\IBVSTdet{EMI 9781 A photomultiplier tube of EUO; Hamamatsu R 4457
photomultiplier tube of TNO}

\IBVSTfil{Johnson $B$ and $V$}

\IBVSTcomp{BD +26\deg 3827}

\IBVSTchk{BD +26\deg 3837}

\IBVSTsysn

\IBVSTdata{Upon request}

\IBVSTtyp{ EA }

\IBVSfig{10cm}{5142-f1.eps}{The light and color curves of DR Vul in
1993}

\IBVSfig{10cm}{5142-f2.eps}{The light and color curves of DR Vul in
1994}

\begin{table}
\caption{Photoelectric minima times of DR Vul, which are obtained
in this work}
\begin{center}
\begin{tabular}{cccrc}
\hline
JD Hel. & \lower6pt\hbox{Filter} & Min. & \lower6pt\hbox{$O-C$} & \lower6pt\hbox{Observatory} \\[-3pt]
2400000\,+ & & Type & & \\
\hline
49162.4627 & $B$ & I & $0.0685$ & EUO \\
49163.4670 & $B$ & II & $-0.0524$ & EUO \\
49180.4704 & $B$ & I & $0.0718$ & EUO \\
49181.4774 & $B$ & II & $-0.0465$ & EUO \\
49189.4755 & $B$, $V$ & I & $0.0746$ & EUO \\
49198.4774 & $B$, $V$ & I & $0.0743$ & EUO \\
49207.4816 & $B$, $V$ & I & $0.0763$ & EUO \\
49208.4878 & $B$, $V$ & II & $-0.0428$ & EUO \\
49216.4854 & $B$, $V$ & I & $0.0779$ & EUO \\
49225.4893 & $B$, $V$ & I & $0.0795$ & EUO \\
49574.3833 & $B$, $V$ & I & $0.1372$ & EUO \\
49575.3788 & $B$, $V$ & II & $0.0075$ & EUO \\
49592.3911 & $B$, $V$ & I & $0.1406$ & EUO \\
49593.3869 & $B$, $V$ & II & $0.0111$ & EUO \\
49601.3953 & $B$, $V$ & I & $0.1425$ & EUO \\
49610.3998 & $B$, $V$ & I & $0.1448$ & EUO \\
49611.3932 & $B$, $V$ & II & $0.0129$ & EUO \\
51737.4606 & $B$, $V$ & I & $0.4294$ & TNO \\
51738.3922 & $B$, $V$ & II & $0.2357$ & TNO \\
\hline
\end{tabular}
\end{center}
\end{table}

\clearpage

\IBVSTrem{DR Vul, which is a well-known eclipsing binary star with
apsidal motion, was observed photoelectrically at the Ege
University Observatory (EUO) on 40 nights during 1993 and 1994
observing seasons and at the T\"{U}B\.{I}TAK (Scientific and
Technical Research Council of Turkey) National Observatory (TNO)
on 2 nights during 2000 observing season. During the observations
no significant light variation of the comparison and check star
was found. The atmospheric extinction coefficients in each color
for each observational night were calculated from the observations
of the comparison star using conventional method. Then, all the
instrumental differential $B$ and $V$ magnitudes (in the sense
variable minus comparison) were corrected for the atmospheric
extinction and the light time effect of the Earth's motion. The
instrumental differential $B$ and $V$ light and $B-V$ color curves are
shown in Figures 1 and 2.\\
During the observations, I obtained 12 primary and 7 secondary
times of minimum light. These times of the minima are presented in
Table 1. The times of the minima given in Table~1 are averaged
values of the eclipse times obtained in $B$ and $V$ colors during the
same observational night. The $O-C$ values were calculated using the
following light elements given by \c{C}i\c{c}ek (1995):
$$
{\rm HJD_{min\,I}} = 2449162.4631(2) + 2\fday2509350(15) \times E.
$$
The photometric phases in Figures~1 and 2 are calculated with the
formula (1). The shape of the light curves of DR Vul is typical of
EA type. As seen from the light curves, the phase of the
mid-secondary minimum (0.447 in 1993 and 0.440 in 1994) is
clearly shifted from 0.5, and no significant variation at 
minima in $B-V$ color curves was found.}

\IBVSTack{We would like to present our thanks to the Ege
University Observatory and T\"{U}B\.{I}TAK National Observatory
for partial financial and equipment support.}

\reference

\c{C}i\c{c}ek, C., 1995, unpublished Ph.D. Thesis, Ege University.

\end{document}
