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\IBVShead{4190}{8 May 1995}

\centerline{\ft PHOTOELECTRIC OBSERVATIONS OF THE}
\centerline{\ft ECLIPSING VARIABLE ER VULPECULAE}
\vskip 8mm

\begintext

The eclipsing binary system ER Vul with the period of 0.6980960 days (Northcott
and Bakos, 1967) was observed during four nights, 29 July-1 August, 1994, with 
the 51 centimeter Cassegrain telescope of Birouni Observatory (Iran, Shiraz, 
latitude=29\degr 36' N, longitude=52\degr 31'48'' E) using a photoelectric 
photometer equipped with an unrefrigerated RCA 4509 photomultiplier tube. The
observations were made through UBV filters which are approximately in the standard
system. The probable errors of a single observation were estimated to be about
$\pm$0.01 in the three colours, i.e., corresponding to a measure of the observational
scatter at a particular phase. The variable was observed differentially with
respect to the comparison star HD\,200270. The star HD\,200425 was observed as
check star.

Figures 1,2 and 3 show the UBV light curves for ER Vul, respectively.

The following light elements given by Ibanoglu et al. (1985) were used in
computing the phases of the individual observations:
\begin{center}
Min.\,I=J.D. Hel. 2440182.2621+0\fd 69809409$\times$E.
\end{center}

Table 1 indicates the photoelectric minimum times of ER Vul, in the three different
filters.
\vskip 1mm
\centerline{Table 1}
\vskip 1mm
\begin{center}
\begin{tabular}{ccl}
\hline
J.D. Hel.&Filter&Min.\\
2449000+& & \\
\hline
\\
563.26074&U&II\\
563.25953&B&II\\
563.24449&V&II\\
564.29480&U&I\\
564.31173&B&I\\
564.28007&V&I\\
\hline
\end{tabular}
\end{center}
\vskip 3mm

\centerline{Table 2}
\vskip 1mm
\begin{center}
\begin{tabular}{lc}
\hline
\ \ \,Date&Phase\\
\hline
\\
29 July 1994&0.9448-0.1319\\
30 July 1994&0.3403-0.5707\\
31 July 1994&0.7729-0.9826\\
1 August 1994&0.2146-0.4309\\
\hline
\end{tabular}
\end{center}
\vfill \eject

\centerline{2}
\epsfysize=11cm
\centerline{\epsffile{4190-f1.ps}}
\centerline{Figure 1}
\epsfysize=11cm
\centerline{\epsffile{4190-f2.ps}}
\centerline{Figure 2}
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\centerline{3}
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\epsfysize=9.5cm
\centerline{\epsffile{4190-f3.ps}}
\centerline{Figure 3}
\vskip 3mm
Our observations indicate the existence of asymmetry, especially
in the beginning of the ascending part of the secondary minimum. These phenomena
can be explained as a result of the presence of a gaseous stream flowing from
the secondary to the primary component, starting off roughly in the inner
Lagrangian point and falling behind the primary as that star moves round on its 
orbit (Struve, 1947). Also we see in our observations a shift for primary
and secondary minima from phases zero and 0.5.

Table 2 lists the dates of observations and phases covered. The data has been
folded so that both primary and secondary minima are clearly visible. These
observations do indicate proximity effects, wave-like distortions, mutual eclipses
and short-term light fluctuations (see Northcott and Bakos (1967)).
\vskip .7cm

\beginauthors
\authorsrightcol
F. ZEINALI
M.T. EDALATI
Physics Dept.,
School of Sciences
University of Ferdowsi,
Mashad, Iran
\vskip 2mm
M.T. MIRTORABI
Birouni Observatory
University of Shiraz,
Shiraz, Iran
\endauthors

\references
Ibanoglu, C., Akan, M. C., Evren, S., and Tunca, Z., 1985, {\it Inf. Bull. Var.
Stars}, No.\,2782

Northcott, R. J. and Bakos, G. A., 1967, {\it Astronomical J.}, {\bf 72}, 89

Struve, O., 1947, {\it Astrophys. J.}, {\bf 106}, 255
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