\documentstyle[twoside,ibvs2,ibvst,ibvse,epsf]{article}

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\IBVShead{5244}{8 March 2002}

\IBVStitletl{HD\,275525, GSC\,02866-01866 and GSC\,03429-01645\,:}{ Three New Delta Scuti Type Variables}

\IBVSauth{Kim, S.-L.$^1$; Kwon, S.-G.$^1$; Youn, J.-H.$^1$; Kyeong, J.-M.$^1$; Lee, J.W.$^2$}

\IBVSinst{Korea Astronomy Observatory, Daejon, 305-348, Korea, e-mail: slkim@kao.re.kr}
\IBVSinst{Dept. of Astronomy and Space Science, Chungbuk National University, Cheongju, 361-763, Korea}

\SIMBADobj{HD 275525}
\SIMBADobj{GSC 02866-01866}
\SIMBADobj{GSC 03429-01645}
\IBVStyp{ DSCT }
\IBVSkey{Delta Scuti stars, photometry}
\IBVSabs{We report photometric results of three new delta Scuti stars,}
\IBVSabs{HD 275525, GSC 02866-01866 and GSC 03429-01645}

\begintext

\IBVSTobs{Sobaeksan Optical Astronomy Observatory, 61cm telescope}

\IBVSTdet{SITe 2K CCD camera (FOV 20\farcm5$\times$20\farcm5)}

\IBVSTfil{$B$, $V$}

\IBVSTsysn

\IBVSTdata{Upon request}

\IBVSEred{Standard CCD-frame reduction using the IRAF package\footnotemark[1]}
\footnotetext[1]{IRAF is distributed by the National Optical Astronomy Observatories,
    which are operated by the Association of Universities for Research
    in Astronomy, Inc., under cooperative agreement with the National Science Foundation.}

\vskip 10mm

\IBVSEstarlis{
HD\,275525       & DSCT & 3 37 15.0 & +40 54 00 & HD\,275605/GSC\,02866-01819 \\
GSC\,02866-01866 & DSCT & 3 36 54.4 & +40 55 40 & HD\,275605/GSC\,02866-01819 \\
GSC\,03429-01645 & DSCT & 9 32 45.7 & +49 38 06 & GSC\,03429-00621/GSC\,03429-01027 \\
}  


\vspace*{-1cm}

\IBVSfig{6.5cm}{5244-f1.eps}{
An observed CCD image (20$\farcm$5$\times$20$\farcm$5) near the eclipsing binary AB Per. Two new variable stars (V1 = HD\,275525 
and V2 = GSC\,02866-01866) and two comparison stars (C1 = HD\,275605 and C2 = GSC\,02866-01819) are marked. 
North is up and east is to the left}


\IBVSfig{12.0cm}{5244-f2.eps}{
Light curves (upper) and its power spectra (lower) of two variable stars discovered in the observed field of AB Per. 
The dominant frequency (vertical dashed line) is about 8.72 c/d for HD\,275525 and about 12.07 c/d for GSC\,02866-01866, respectively.
Magnitude differences between comparison star (C1) and check star (C2) are plotted in the top panel}



\IBVSfig{7cm}{5244-f3.eps}{
An observed CCD image (20$\farcm$5$\times$20$\farcm$5) near the eclipsing binary XZ UMa. A new variable star (V = GSC\,03429-01645)
and two comparison stars (C1 = GSC\,03429-00621 and C2 = GSC\,03429-01027) are marked. 
North is up and east is to the left}


\IBVSfig{9.2cm}{5244-f4.eps}{
Light curves (upper) and its power spectra (lower) of a variable star discovered in the observed field of XZ UMa. 
A dominant frequency is shown at about 27.0 c/d (vertical dashed line). 
Magnitude differences between comparison star (C1) and check star (C2) are plotted in the top panel}


\IBVSTrem{
As a part of the observational survey to search for $\delta$ Scuti type pulsating components in eclipsing binary systems 
(Kim et al. 2002), we performed time-series CCD observations of AB Per and XZ UMa in December 23 and 28, 2001 with $V$ filter.
After reducing the data, we have discovered serendipitously three new variable stars in the observed fields.
To confirm this variability, we obtained again time-series CCD frames in January 30 and 31, 2002 with $B$ filter.
We applied classical two-star differential photometry to get differential magnitudes and
derived variable periods from the discrete Fourier analysis (Scargle 1989).
\\
Maximum amplitudes are about 0\fmm03 in V-band and 0\fmm04 in B-band for HD\,275525,
about 0\fmm04 in V-band and 0\fmm05 in B-band for GSC\,02866-01866 and
about 0$\fmm$03 in V-band and 0$\fmm$04 in B-band for GSC\,03429-01645.
Light variations show smooth and very complicated curves, indicating that multiple periods are superimposed.
The dominant frequency for each variable star is about 8.72 c/d (0\fday115) for HD\,275525, about 12.07 c/d
(0\fday083) for GSC\,02866-01866 and about 27.0 c/d (0\fday037) for GSC\,03429-01645, respectively.
Considering the above variable characteristics,
we suggest that the three variable stars can be identified as $\delta$ Scuti type pulsating variables. 
}

\IBVSTack{This research made use of the SIMBAD database, operated at CDS, Strasbourg, France}

\references

Kim, S.-L., Lee, J.W., Kwon, S.-G., Youn, J.-H., Kyeong, J.-M., 2002, {\it Journal of the Korean Astronomical Society},
to be submitted

Scargle, J.D., 1989, {\it ApJ}, {\bf 343}, 874

\endreferences


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