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\begin{document}
\IBVShead{4669}{9 February 1999}

\IBVStitle{V473 C\lowercase{as}: FIRST ELEMENTS AND LIGHTCURVE}

\IBVSauth{ W. Moschner$^{1,3}$, P. Frank$^{2,3}$, U. Bastian$^{4}$}


\IBVSinst{D-57368 Lennestadt, Germany,
      e-mail:  wolfgang.moschner@t-online.de}
\IBVSinst{D-84149 Velden, Germany, e-mail: frank.velden@t-online.de}
\IBVSinst{Bundesdeutsche Arbeitsgemeinschaft
      f\"ur Ver\"anderliche Sterne e.V. (BAV),
      Munsterdamm 90,
      D-12169 Berlin, Germany }
\IBVSinst{Astronomisches Rechen-Institut, M\"onchhofstr.\ 14, D-69120
    Heidelberg, Germany,\\ e-mail: s01@ix.urz.uni-heidelberg.de}


\SIMBADobj{V473 Cas}
\IBVStyp{ EB }
\IBVSkey{eclipsing binaries}
\IBVSabs{Variability type and precise lightcurve elements for}
\IBVSabs{V473~Cas were derived from CCD photometry. V473~Cas}
\IBVSabs{is an EB-type eclipsing binary with a period of 0.4~days}

\begintext

V473 Cas = SON 8461 = GSC 3679-1417 was discovered by Hoffmeister
(1964) on photographic plates of the Sonneberg Observatory. He
classified the star as a short-period variable with a photographic
magnitude range of 13.5--14.0. A first follow-up investigation was
performed by Gessner and Meinunger (1973). On the plates of the
Sonneberg astrograph (400/1600 mm and 400/1950 mm) they found six
(partly uncertain) minima in the period between JD~2438286 and
JD~2438328 (42~days) which were insufficient for determining a
period.  Nevertheless they classified the star as an eclipsing binary
and gave the photographic magnitude range as 13.4--14.0.  This is the
information given for V473~Cas in the fourth edition of the GCVS
(Kholopov et~al.~1985).

About 15~years after Gessner and Meinunger we put V473~Cas on our
observing program, after a photographic minimum had accidentally been
found by Peter Frank in a series of photographs aimed at V470~Cas. Our
subsequent CCD observations were made with an SBIG~ST6 camera without
filters, attached to a 32-cm Ritchey-Chretien telescope with $f =
1740$~mm (Wolfgang Moschner), and with an OES-LcCCD~11 camera without
filters, attached to a 30cm flatfield camera with $f = 576$~mm (Peter
Frank). The integration times were 60 seconds at both telescopes.  The
CCD observations cover 3~years. GSC~3679-2081 served as the comparison
star; several other stars in the same field were used to check its
constancy.

V473~Cas turned out to be a $\beta$-Lyr-type eclipsing binary (see
Fig.~1).  In the instrumental system of the ST6~camera the amplitude of
variability is 0.85~mag for the primary minima and 0.30~mag for the
secondary minima. From 17~individual nightly CCD series we determined
moments of primary minima, using the method of Kwee and
van~Woerden~(1956).  They are listed in Table~1.

Using the 17 CCD minima, a weighted least-squares
fit led to the following
elements:
$$
\begin{array}{r@{}r@{}l}
\hbox{Min.\ I}=\hbox{JDhel\ } 2450334.4400&{}+0\fday41546073&{}\times  E.\\
                                   \pm 2&            \pm 4& \\
\end{array}
$$

\begin{table}
{\normalsize
\caption{Observed times of minima for V473 Cas}
\begin{center}
\begin{tabular}{clcccrl}
\hline
No.   & Observer &  Type  & Weight & JD hel.  &  O$-$C &  Ref. \\
\hline
1&W. Moschner&P&0&29086.4960&$-$0.0359&this paper\\
2&W. Moschner&P&0&29106.4170&$-$0.0570&this paper\\
3&W. Moschner&P&0&29108.5170&$-$0.0343&this paper\\
4&W. Moschner&P&0&29553.4580&$-$0.0517&this paper\\
5&W. Moschner&P&0&30259.5120&$-$0.0733&this paper\\
6&W. Moschner&P&0&36604.2810&$-$0.0128&this paper\\
7&W. Moschner&P&0&38044.2840&+0.0033&this paper\\
8&I. Meinunger&P&0&38286.4970&+0.0027&VSS 7\\
9&W. Moschner&P&0&38291.4910&+0.0112&this paper\\
10&I. Meinunger&P&0&38296.4670&+0.0017&VSS 7\\
11&I. Meinunger&P&0&38318.4830&$-$0.0048&VSS 7\\
12&I. Meinunger&P&0&38322.6190&$-$0.0018&VSS 7\\
13&I. Meinunger&P&0&38325.5390&$-$0.0204&VSS 7\\
14&W. Moschner&P&0&38327.6310&+0.0061&this paper\\
15&I. Meinunger&P&0&38328.4440&$-$0.0118&VSS 7\\
16&W. Moschner&P&0&38339.2360&$-$0.0218&this paper\\
17&W. Moschner&P&0&38343.4280&+0.0156&this paper\\
18&W. Moschner&P&0&38372.5010&+0.0063&this paper\\
19&W. Moschner&P&0&38640.4430&$-$0.0238&this paper\\
20&W. Moschner&P&0&39054.4780&+0.0045&this paper\\
21&W. Moschner&P&0&39063.3790&$-$0.0269&this paper\\
22&W. Moschner&P&0&39414.4550&$-$0.0152&this paper\\
23&W. Moschner&P&0&40127.4190&+0.0182&this paper\\
24&W. Moschner&P&0&45607.3480&+0.0202&this paper\\
25&W. Moschner&P&0&45940.5400&+0.0127&this paper\\
26&W. Moschner&P&0&46685.4560&+0.0076&this paper\\
27&P. Frank&F&5&47776.4540&+0.0057&this paper\\
28&P. Frank&E&5&50043.4058&$-$0.0040&this paper\\
29&P. Frank&E&5&50043.6116&$-$0.0059&this paper\\
30&W. Moschner&E&10&50330.4931&+0.0000&this paper\\
31&W. Moschner&E&10&50332.5719&+0.0015&this paper\\
32&W. Moschner&E&10&50334.4400&+0.0000&this paper\\
33&W. Moschner&E&10&50368.3019&+0.0019&this paper\\
34&W. Moschner&E&10&50369.3390&+0.0003&this paper\\
35&W. Moschner&E&10&50376.3968&$-$0.0047&this paper\\
36&F. Agerer&E&10&50465.3090&$-$0.0011&this paper\\
37&P. Frank&E&10&50604.4905&+0.0010&this paper\\
38&P. Frank&E&10&50652.4836&+0.0084&this paper\\
39&W. Moschner&E&10&50668.4700&$-$0.0004&this paper\\
40&P. Frank&E&10&50672.4121&$-$0.0052&this paper\\
41&P. Frank&E&10&50673.4566&+0.0006&this paper\\
42&W. Moschner&E&10&50685.5020&$-$0.0023&this paper\\
43&W. Moschner&E&5&51041.5544&+0.0002&this paper\\
44&W. Moschner&E&10&51079.3588&$-$0.0023&this paper\\
\hline
\end{tabular}
\end{center}
Notes to Table~1:  O$-$C residuals were computed with respect to the
elements derived in this paper. In the third column, ``P" denotes
minimum light on a single photographic plate, ``F" a minimum time
derived from a dense series of photographic plates, and ``E" a minimum
time from a dense series of CCD measurements.  The fourth column lists
the weights used in the least-squares adjustment for the elements. In
the last column, ``VSS~7" is an abbreviation for Gessner \&  Meinunger
(1973).  Minima nos.~38 and 40 are secondary minima, all others are
primary minima.}
\end{table}

\IBVSfig{10.5cm}{4669-f1.eps}{Folded differential lightcurve of V473~Cas.}

\IBVSfig{9.5cm}{4669-f2.ps}{O$-$C~diagram for V473~Cas using the elements derived in this paper.}


\vspace{-23pt}
In addition to the CCD observations, one of us (Wolfgang Moschner)
investigated the variable on about 320~photographic plates of the
0.4-m~astrographs of the Sonneberg Observatory.  Twenty additional times
of minimum light could be found in this way, from plates taken between
JD~2429086 and JD~2446685. They are listed in Table~1.  Residuals from
the least-squares fit are listed in Table~1 and displayed in the
O$-$C~diagram, Fig.~2, both for the CCD minima which were used for the
fit, and for the photographic minima which were not used.  A small
decrease in the period around or before JD~2438000 is indicated in
Fig.~2.

Acknowledgements:  We thank for help and assistance by the management
and staff of Sonneberg Observatory, especially by Dr.\ Peter Kroll in
using the library and plate archive.  This research made use of the
SIMBAD data base, operated by the CDS at Strasbourg, France.

\references

Gessner H., Meinunger I., 1973, {\it Ver\"offentlichungen der Sternwarte in Sonneberg},
{\bf 7}, 619

Hoffmeister C., 1964, {\it Mitteilungen \"uber
Ver\"anderliche Sterne (Sonneberg)}, {\bf 2}, 99

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

Kwee, K.K., van Woerden, H., 1956, {\it Bull.\ Astron.\ Inst.\
Netherlands}, {\bf 12}, 32

\end{document}
