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\IBVShead{5362}{8 January 2003}

\IBVStitle{A New Variable Star in the Vicinity of YY H\lowercase{er}}

\IBVSauth{Pejcha, O.$^{1,5}$; H\'{a}jek, P.$^6$; Koss, K.$^{2,6}$; Kudrn\'{a}\v{c}ov\'{a}, J.$^{3,6}$; Motl, D.$^{4,6}$; Sobotka, P.$^5$}

\IBVSinst{Okrouhl\'{a} 1, 625 00 Brno, Czech Republic; e-mail: {\tt pejcha@astro.sci.muni.cz}}

\IBVSinst{Lu\v{c}n\'{\i} 7, 695 01 Hodon\'{\i}n, Czech Republic;
e-mail: {\tt karel.koss@tiscali.cz}}

\IBVSinst{Kam\'{\i}nky 7, 634 00 Brno, Czech Republic; e-mail: {\tt jkudrnacova@centrum.cz}}

\IBVSinst{\v{C}tvrt\v{e} 12, 634 00 Brno, Czech Republic; e-mail: {\tt dmotl@volny.cz}}

\IBVSinst{MEDUZA, c/o Nicholas Copernicus Observatory and Planetarium,
Krav\'{\i} hora 2, 616 00 Brno, Czech Republic; e-mail: {\tt sobotka@physics.muni.cz}}

\IBVSinst{Vy\v{s}kov Observatory, P.O. Box 43, 628 01 Vy\v{s}kov, Czech Republic; e-mail: {\tt phajek@sci.muni.cz}}

\IBVSabs{We present multi-colour CCD observations of IRAS F18122+2053,}
\IBVSabs{a new semiregular variable star in the close vicinity of YY Her.}

\SIMBADobj{IRAS F18122+2053}
\IBVStyp{ SR }
\IBVSkey{photometry}

\begintext

While monitoring the field of YY~Her (cf. the observing campaign
called up by Hric et al., 2001, and Sobotka \& Hric, 2001, on
behalf of the MEDUZA\IBVSfm\IBVSfoot{{\tt http://www.meduza.info}}
group) we have noted that a very red star IRAS F18122+2053 ($V
\approx 16.5$ mag, $V-R \approx 2.5$ mag, $R-I \approx 2.5$ mag)
located at $\alpha = 18\hr 14\mm 23\fsec15$, $\delta = +20\deg
54\arcm 28\farcs6$ (J2000) varies its brightness. The observations
were carried out using the 0.4~m ($f = 1.75$ m) Newtonian
telescope of Nicholas Copernicus Observatory and Planetarium in
Brno and the 0.3~m ($f = 1.2$ m) Newtonian telescope of the
Vy\v{s}kov Observatory both equipped with SBIG~ST-7 CCD camera and
$VR_CI_C$ filters. Frames (typically two to six in each band per
night) were processed using MUNIDOS 2.2 (Hroch, Nov\'{a}k and
Kr\'{a}l, 2001). Although the field stars were measured by Henden
and Munari (2001), we did not attempt to put our measurements on
the standard system due to the redness of the star. Instead,
GSC~01579~00432 ($V = 12\fmm040$; Henden and Munari, 2001) was
chosen as the comparison star for differential photometry. Its
constancy was checked by using several field stars. The spectral
response differences between observatories were removed by a
zero-point shift. Weighted averages of CCD observations made on
the same night with the same filter and at one observatory were
made. Magnitude errors served as weights. The data are available
through IBVS website as \hbox{5362-t1.txt}. 

\IBVSedata{5362-t1.txt}
%\IBVSdataKey{5362-t1.txt}{IRAS F18122+2053}{photometry}

In Figure 1 we present $R$ and $I$ differential light curves of
IRAS F18122+2053. Data in $V$ band confirm the variability, but
are not plotted due to their low quality.

Averaged observations were submitted to a PDM period searching
algorithm (Widjaja, 1996) resulting a period of 
98 days. The colour of the star and the
amplitude and period of the light variations indicate that, 
IRAS F18122+2053 is most probably a semiregular variable star.

\IBVSfig{7cm}{5362-f1.eps}{Light curves of IRAS F18122+2053. Open
circles and filled squares are measurements in $R$ and $I$
filters, respectively. The datasets were shifted for plot
clarity.}
%\IBVSfigKey{5362-f1.eps}{IRAS F18122+2053}{light curve}

\newpage

{\it Acknowledgements:} We acknowledge overall support and the use
of the telescope with CCD camera of the Nicholas Copernicus
Observatory and Planetarium. We would like to thank L. Kr\'{a}l
for software support.

This work has made use of the SIMBAD database, operated at CDS,
Strasbourg, France. The NASA ADS Abstract Service was used to
access data and references.

\references

Henden, A. A., Munari, U., 2001, {\it A\&A}, {\bf 372}, 145  
%%\BIBCODE {2001A&A...372..145H}

Hric, L., et al., 2001, {\it IBVS}, No.\ 5046  
%%\BIBCODE {2001IBVS.5046....1H}

Hroch, F., Nov\'{a}k, R., Kr\'{a}l, L., 2002, {\tt http://munipack.astronomy.cz}

Sobotka, P., Hric, L., 2001, {\it MEDUZA Circular}, {\bf 21}, 1 (available through \\
{\tt ftp://astro.sci.muni.cz/meduza/circular/21cirk.pdf})

Widjaja, A., 1996, {\tt http://www.kusastro.kyoto-u.ac.jp/vsnet/etc/prog.html}

\endreferences

\end{document}

