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\IBVShead{4308}{13 March 1996}

\centerline{\ft NEW ELEMENTS FOR THE ECLIPSING BINARY ZZ Cnc}
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\begintext

ZZ Cnc = HD\,65025 (A0) = BD\,+11\degr 172 (8.7) = BV\,361 was discovered an
as Algol-type eclipsing binary by Strohmeier
(1961). The GCVS (Kholopov et al., 1985) contains first elements
derived by Strohmeier (1962a,b):
\vskip 1mm
\hspace*{3cm} Min = J.D.\,2426770.350 + 25.5950 $\times$ E  \hfill (1)
  \centerline{(EA 9.40 - 10.90 m$_{pg}$)}
\vskip 1mm

Since the period is rather long, further photometric observations
of the star were not numerous. Only one minimum has been published 
up to now (Isles, 1986).

Brightness of ZZ Cnc was estimated using the photographic plates of the
Sonneberg Sky Survey to check the validity of the above elements.
These elements were found to be not correct. In the
paper of Strohmeier only minima with even numbers of epoch were
listed.

The magnitude values determined from 195 plates covering the years 1975-1995, have
pointed out to double the value of the period found by Strohmeier.
The light curve folded on the new period is shown in Figure 1. 
Period analysis of that material by means of a method published by
Renson (1978) has been done (Figure 2) confirming the above conclusion.

A weighted least squares fit yields the following linear
ephemeris:
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\hspace*{3cm} Min = J.D.\,2444635.44 + 51\fd 1894 $\times$ E  \hfill (2)
\hspace*{72mm}$\pm$3\ \ \ \ \ \ \ \ \ \ \ $\pm$2

\centerline{(EA 10.10 - 11.55/10.20(:) m$_{pg}$; D=0.07$\times$P)}
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\centerline{Table 1. Observed times of minima for ZZ Cnc, epochs and residuals}
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\begin{center}
\begin{tabular}{lrrcl}
\hline
Minimum      &   Epoch & (O$-$C$_2$) &  Weight  &     Observer\\
JD 2400000+ & & & & \\
\hline
\\
  26770.35   &   $-$349 &    0.005  &   1   &  Strohmeier\\
  27538.33   &   $-$334 &    0.145  &   1    & \\
  27896.334  &   $-$327 &   $-$0.177&     1& \\
  37315.47   &   $-$143 &    0.114  &   1& \\
  44635.378  &      0 &   $-$0.059  &   2& Berthold\\
  45403.367  &     15 &    0.090    & 2& \\
  45761.401  &     22 &   $-$0.202  &   2& \\
  47860.530  &     63 &    0.163    & 2& \\
  48679.389  &     79 &   $-$0.008  &   2& \\
  48986.507  &     85 &   $-$0.027  &   2& \\
\hline
\end{tabular}
\end{center}
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\centerline{2}
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\centerline{\epsffile{4308-f1.ps}}
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\begin{center}
Figure 1. Photographic light curve of ZZ Cnc plotted using the elements (2).
Photographic magnitudes were obtained by a photographic photometer
and refer to the Harvard-Groningen SA 76.
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\large
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\centerline{\epsffile{4308-f2.ps}}
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\begin{center}
Figure 2. Periodogram (20-55 days) of ZZ Cnc.
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\large
\vfill \eject

\centerline{3}
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The minimum of Isles (derived from 6 visual observations) has not
been considered.


This paper could be prepared by courtesy of management and staff of
Sonneberg Observatory.

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\beginauthors
\authorsrightcol
Thomas BERTHOLD
Bundesdeutsche Arbeitsgemeinschaft
f\"ur Ver\"anderliche Sterne e.V.
Bruno-H.-B\"urgel-Sternwarte Hartha
T\"opelstra\ss e 43
D-04746 Hartha
\endauthors

\references

Isles, J.E. , 1986, {\it Brit. Astr. Assoc. Var. Star Section Circ.},
No.\,63

Kholopov, P.N. et al., 1985, {\it Gen. Cat. of. Var. Stars}, 4th Ed.

Renson, P., 1978, {\it Astron. Astrophys.}, {\bf 63}, 125

Strohmeier, W., 1961, {\it Astron. Nachrichten}, {\bf 286}, 3, 133

Strohmeier, W., 1962a, {\it Ver\"off. Remeis Sternwarte Bamberg}, V.13.11

Strohmeier, W., 1962b, {\it Inf. Bull. Var. Stars}, No.\,9
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