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\begin{document}
\IBVShead{4386}{25 October 1996}
\title{NSV 6177: First elements and lightcurve}
\vspace{-2em}
\centerline{[BAV Mitteilungen Nr. 88]}
\vskip 8mm

\begintext

NSV\,6177 = SVS\,1257 was discovered by Kurochkin (1959) in an
investigation of new variables on 9 photographic plates of the field
SA\,57, centered at 13\fh04\fmm +30\degr ~(1900). In this search 10 new variables
were found with SVS\,1257 among them. It was classified as a
possibly RR~Lyrae type variable with a brightness range between 12\fm3
and 13\fm0. An identification chart was given but no
light-curve. Since elements were not published, SVS\,1257 is
listed as NSV\,6177 in the New Catalogue of Suspected Variable Stars
(Kholopov et al.~1982).

%On plates of a photographic Sky Patrol with a 400mm-astrograph and
%with a 160mm-camera 35 additional times of minimum light could be
%found (Kurochkin 1959). 

Almost 40 years later we put NSV\,6177 on our observing program.
The CCD observations were made with SBIG ST6 cameras without filters,
attached to a 32-cm Ritchey-Chretien telescope with f = 1740 mm (W.~Moschner)
and a 12-cm astrograph with f = 509 mm (P.~Frank). The integration time was
45 seconds at the RC-telescope and 90 seconds at the astrograph. Our
CCD observations cover 44 days. 

The shape of the light-curve reveals NSV\,6177 surprisingly as variable
of $\beta$~Lyrae type (Figure 2). All minima times were calculated with the Kwee
-- van Woerden method (Kwee, van Woerden 1956). In the instrumental
system of our CCD observations the depth of the primary and the
secondary minima were found to be 0\fm48 and 0\fm28, respectively.

Based on our conclusion that NSV\,6177 is of $\beta$ Lyrae type, we
reinterpreted Kurochkin's individual estimations in the following way:
Each observation fainter than 12\fm85 was considered to be a
minimum. Weighting CCD minima 10 times higher than Kurochkin's
photographic data, we obtained the following ephemeris:
\vskip 1mm
\hspace*{3cm}Min\,I = HJD\,2450186.398 + 0\fd 4068974 $\times$ E \hfill (1)
\hspace*{7.6cm}$\pm$1\ \ \ \ \ \ \ \ \ \ \ \ \ \ $\pm$1
\vskip 1mm
 
The resulting O$-$C diagram (Figure 3) shows a large scattering of the
photographic data. This is caused by the interpretation of dim magnitudes as minima (the related moments may not be the exact minima
times) as well as the rather long exposure times of the photographic plates
(not given by Kurochkin, but we assume some 60 minutes) compared to
the short period of the star.
\vfill \eject

\centerline{2}
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\centerline{\epsffile{4386-f1.ps}}
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Figure 1. Identification chart for NSV\,6177 (A), comparison (B) and check star (C). The size of the frame is 12$\times$16 arcmin, North is on top.
\end{center}


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\centerline{\epsffile{4386-f2.ps}}
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Figure 2. Differential light curve of NSV\,6177 computed with
respect to the first elements
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\vfill \eject

\centerline{3}

\begin{center}
\normalsize
Table 1. Observed times of minima for NSV\,6177, epochs and residuals computed
with respect to the ephemeris derived in this paper
\vskip 1mm
\begin{tabular}{rlrcrrc}
\hline\\
N&JD hel&W&T$^{\star}$&Epoch&O$-$C&Observer\\
 &2400000+& & & & & \\
\hline
\\
   1 & 18062.431 &  1 &   P   &  $-$78949.5 &    $-$0.028  & [1] \\
   2 & 18446.394 &  1 &   P   &  $-$78005.0 &    +0.028  & [1] \\
   3 & 19116.370 &  1 &   P   &  $-$76359.5 &    +0.047  & [1] \\
   4 & 19122.387 &  1 &   P   &  $-$76344.5 &    $-$0.039  & [1] \\
   5 & 19153.377 &  1 &   P   &  $-$76268.5 &    +0.026  & [1] \\
   6 & 33034.425 &  1 &   P   &  $-$42153.0 &    $-$0.027  & [1] \\
   7 & 34116.361 &  1 &   P   &  $-$39494.0 &    $-$0.031  & [1] \\
   8 & 34117.362 &  1 &   P   &  $-$39492.5 &    $-$0.047  & [1] \\
   9 & 34118.411 &  1 &   P   &  $-$39489.0 &    $-$0.016  & [1] \\
  10 & 34126.324 &  1 &   P   &  $-$39470.5 &    $-$0.037  & [1] \\
  11 & 34127.361 &  1 &   P   &  $-$39467.0 &    $-$0.017  & [1] \\
  12 & 34130.377 &  1 &   P   &  $-$39460.5 &    $-$0.053  & [1] \\
  13 & 34420.542 &  1 &   P   &  $-$38747.5 &    $-$0.006  & [1] \\
  14 & 34472.405 &  1 &   P   &  $-$38619.0 &    $-$0.022  & [1] \\
  15 & 34477.334 &  1 &   P   &  $-$38607.0 &    +0.024  & [1] \\
  16 & 34485.446 &  1 &   P   &  $-$38587.0 &    $-$0.002  & [1] \\
  17 & 34826420 &  1 &   P   &   $-$37749.0 &    $-$0.008  & [1] \\
  18 & 34834552 &  1 &   P   &   $-$37729.0 &    $-$0.014  & [1] \\
  19 & 35219486 &  1 &   P   &   $-$36783.0 &    $-$0.005  & [1] \\
  20 & 35246368 &  1 &   P   &   $-$36717.0 &    +0.022  & [1] \\
  21 & 35540541 &  1 &   P   &   $-$35994.0 &    +0.008  & [1] \\
  22 & 35547439 &  1 &   P   &   $-$35977.0 &    $-$0.011  & [1] \\
  23 & 35550.290 &  1 &   P   &  $-$35970.0 &    $-$0.009  & [1] \\
  24 & 35598.307 &  1 &   P   &  $-$35852.0 &    $-$0.005  & [1] \\
  25 & 35907.563 &  1 &   P   &  $-$35092.0 &    +0.009  & [1] \\
  26 & 35907.394 &  1 &   P   &  $-$35093.5 &    +0.043  & [1] \\
  27 & 35923.419 &  1 &   P   &  $-$35053.0 &    $-$0.004  & [1] \\
  28 & 35929.544 &  1 &   P   &  $-$35038.0 &    +0.017  & [1] \\
  29 & 35930.340 &  1 &   P   &  $-$35036.0 &    $-$0.001  & [1] \\
  30 & 35930.354 &  1 &   P   &  $-$35036.0 &    +0.013  & [1] \\
  31 & 35932.382 &  1 &   P   &  $-$35031.0 &    +0.007  & [1] \\
  32 & 35933.408 &  1 &   P   &  $-$35029.5 &    +0.016  & [1] \\
  33 & 35954.350 &  1 &   P   &  $-$34977.0 &    +0.002  & [1] \\
  34 & 35956.379 &  1 &   P   &  $-$34972.0 &    $-$0.003  & [1] \\
  35 & 35956.401 &  1 &   P   &  $-$34972.0 &    +0.019  & [1] \\
  36 & 50157.5094& 10 &   E   &     $-$71.0 &    +0.0011 & [2] \\
  37 & 50163.4073& 10 &   E   &     $-$57.5 &    $-$0.0010 & [2] \\
  38 & 50180.4990& 10 &   E   &     $-$15.5 &    +0.0010 & [3] \\
  39 & 50186.3980& 10 &   E   &       0.0 &    +0.0000 & [3] \\
  40 & 50188.4319& 10 &   E   &       5.0 &    $-$0.0006 & [3] \\
  41 & 50189.4515& 10 &   E   &       7.5 &    +0.0018 & [3] \\
  42 & 50199.4185& 10 &   E   &      32.0 &    $-$0.0002 & [3] \\
  43 & 50201.4534& 10 &   E   &      37.0 &    +0.0002 & [3] \\
\hline\\
\end{tabular}
\end{center}
\centerline{$^{\star}$ E\ denotes CCD observed maxima, P\ are
  photographic; W -- relative weight.}
\vskip 3mm

[1]: Kurochkin (1959),

[2]: P. Frank: this paper,

[3]: W. Moschner: this paper.

\large

\vfill \eject

\centerline{4}
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\centerline{\epsffile{4386-f3.ps}}
\begin{center}
Figure 3. O$-$C diagram of NSV\,6177. $+$ -- photographic minima by
Kurochkin, $\times$ -- CCD by the authors
\end{center}


\vskip 1cm

\beginauthors
\authorsrightcol
 P.~FRANK
 J. MOSCHNER
 W.~MOSCHNER
 E-mail:
 wolfgang.moschner@t-online.de                     %email

 Bundesdeutsche Arbeitsgemeinschaft
 f\"ur Ver\"anderliche Sterne e.V. 
 (BAV)
 Munsterdamm 90,
 D-12169 Berlin, Germany
\endauthors

\references
 
Kholopov, P.N.~et al.: 1982, New Catalogue of Suspected Variable
           Stars

Kurochkin, N.: 1959, {\it Variable Stars}, {\bf 12}, 409

Kwee, K. K., van Woerden, H.: 1956, {\it Bull. Astr. Inst. Netherlands},
 {\bf 12}, 327

\end{document}

