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\IBVShead{5730}{20 October 2006}

\IBVStitle{GSC~02799-00902: a New {\boldmath $\delta$} S\lowercase{ct} Variable}

\IBVSauth{Zhang, X.B.; Zhang, R.X.}

\IBVSinsto{National Astronomical Observatories, Chinese Academy of
Sciences, Beijing 100012, China }

\SIMBADobj{GSC 02799-00902}
\IBVSkey{photometry - Delta Scuti stars}

\begintext

GSC~02799-00902 ($\alpha_{2000}=01\hr01\mm26\fsec55$, $\delta_{2000}=
+38\deg03\arcm13\farcs0$) is a never-studied faint star ($V\simeq11.1$ mag) in
the field of the eclipsing binary WZ And. In the 2004 observation
season, we have made a time-series CCD photometry of WZ And (Zhang
\& Zhang, 2006). GSC 2799-902 was observed as one of the reference
stars. Nelson (2000) also used this star as comparison for WZ And. During data 
reductions, we found that it could be a new
pulsating variable star. To identify its spectral type as well as
the variation classification, spectroscopy of the star was
performed later. In this paper, we report the discovery of this new
variable. A preliminary discussion on the properties and pulsating
nature of the star is given.

Our photometric observations were carried out at the Xinglong Station of NAOC on
three nights between 12 and 14 October, 2004. The data were collected using the 85-cm
reflector with a AP7P $512\times512$ CCD camera. A single Johnson $V$ filter was
used. The exposure time was 60 seconds for each measurement. The star GSC~02799-00396
was used as the comparison star. The spectroscopy was made on 25 Oct., 2004 with the
2.16-m telescope at the Xinglong Station of NAOC{}. A Zeiss universal spectrograph
was used with a Tektronix 1~k${}\times{}$1~k CCD and a 200~\AA\,mm$^{-1}$ grating. A
He-Ar lamp was used for wavelength calibration.

The light curves obtained for the star are shown in Fig.~1. It
shows that GSC~02799-00902 is obviously an oscillating variable
with an observed total $V$ amplitude of about 0.04 mag. The
spectrum presented in Fig.~2 suggests a spectral type of F0-F2 for
the star. Therefore we conclude that GSC~02799-00902 could be a
new $\delta$ Scuti variable.

To search for periodicity of the light variations, a Fourier
analysis was performed by using the algorithm {\tt Period98} (Sperl,
1998). The step-by-step amplitude spectra produced from the
data are shown in Fig.~3. The Fourier analysis reveals a dominant
pulsating frequency $f_1$ at 9.9046 c/d. Another frequency could be
detected at $f_2 = 5.3804$ c/d, though the S/N ratio is relatively
low. It seems that this star could be oscillating with multi-period.
The main results of the frequency analysis are given in Table 1.
With the 2-frequency model, a fitting to the observed light curve is
made as shown in Fig.~1.

\newpage

\IBVSfig{7.6cm}{5730-f1.ps}{Observed $V$-band light curve of
GSC~02799-00902, fitted with a 2-frequency model}
\IBVSfigKey{5730-f1.ps}{GSC 02799-00902}{light curve}

\IBVSfig{7.6cm}{5730-f2.ps}{The 1-D spectrum of GSC~02799-00902}
\IBVSfigKey{5730-f2.ps}{GSC 02799-00902}{spectrum}

\newpage

\IBVSfig{7.6cm}{5730-f3.ps}{The spectral window and amplitude
spectrum of GSC~02799-00902 photometric data}
\IBVSfigKey{5730-f3.ps}{GSC 02799-00902}{periodogram}

\IBVSfigNoCaption{8.6cm}{5730-f4.ps}
\IBVSfigKey{5730-f4.ps}{GSC 02799-00902}{finding chart}
\IBVSecomment{Finding chart}

\newpage

\begin{table}
\begin{center}
{\normalsize Table 1. Results of the frequency analysis} \vskip2mm
\begin{tabular}{ccccc}
\hline
Name & Frequency (c/d) & Ampl./2 (mmag) & Phase & S/N \\
\hline
$f_1$ & 9.9046 & 7.84 & 0.5962629 & 8.4 \\
$f_2$ & 5.3804 & 4.12 & 0.5564623 & 3.8 \\
\hline
\end{tabular}
\end{center}
\end{table}

\references

Nelson, R.H., 2000, {\it IBVS}, No.\ 4840

Sperl, M., 1998, Manual for Period98 (V1.0.4). A period
search-program for Windows and Unix,
http://www.univie.ac.at/tops/Period98/

Zhang, X.B., Zhang, R.X., 2006, {\it New A.}, {\bf 11}, 339

\endreferences

\IBVSedata{5730-t2.txt}
\IBVSdataKey{5730-t2.txt}{GSC 02799-00902}{photometry}
\IBVSecomment{Photometric data}


\end{document}
