\documentstyle[epsf]{article}

\input ibvs.sty

\begin{document}
\IBVShead{4317}{9 April 1996}

\begin{center}
\ft PHOTOMETRIC OBSERVATIONS OF THE NEW BRIGHT CLASSICAL 
 CEPHEID SAO\,25009 = HD\,32456
\end{center}

\vskip 8mm

\begintext

The star SAO 25009 (HD\,32456, BD\,+55\degr 0956, PPM\,29610, AGK\,+55\degr 0438,
GSC 3738.0234) of spectral type G5 is one of the variables discovered
by the TYCHO Instrument of the ESA Hipparcos Satellite. It was
announced to have a magnitude variation range between 7.73 and 8.51 in
T magnitudes (TYCHO magnitudes) with a possible 90 day period (Makarov 
et al., 1994).  
As a result of an observational program proposed by Bastian (1995),
Born (1995) observed visually the star indicating that it should be a
new delta Cephei star with a 3.25 day period.

Without previous knowledge of the work by Born we proceeded, from 29 October
1995, to visually monitor SAO\,25009. Initial observations indicated that the 
period of the light variation was much shorter than the announced value of 90 
days. For this reason, we decided to continue our monitoring work
photometrically. Due to the fact that we had to deal with a rather bright
star, and also the need to work with a wide field to include suitable
comparison stars in terms of brightness and color index, from 30 December
1995 to 24 February 1996 we undertook the task of observing SAO\,25009 in 
the V band at Piera Observatory (Spain) using a 6-cm finder telescope and
a LYNXX-2 CCD camera. We chose  SAO\,25029 (HD\,32606, 
BD\,+55\degr 0958, PPM\,29633, GSC\,3739.0913) as a comparison star. 
\vskip 3.8cm
\epsfysize=6.4cm
\centerline{\epsffile{4317-f1.ps}}
\vskip -3cm
\centerline{Figure 1}
\vfill \eject

\centerline{2}
\vskip 1mm

At the same time, we took some brightness measurements using the 0.41-m telescope 
at Mollet Observatory (Spain) and an Optec SSP-3 photometer. We also 
determined the V and B magnitudes of the comparison star SAO\,25029 using HR\,1511, HR\,1546, and HR\,1561 as reference stars.

Our observations allowed us to conclude that SAO 25009 is a bright
cepheid (V=7.19 $\pm$0.05 magnitudes at maximum light) with a period close
to 3.295 days, and an asymmetry factor (M$-$m)/P=0.30 $\pm$0.02 with a
variation range of 0.60 $\pm$0.01 magnitudes in the V band (Figure 1).
According to light curve shape, SAO\,25009 can be classified as a
classical cepheid. Nevertheless this last statement should be confirmed
by other observational means.

We derived the following ephemeris:
\vskip 1mm
\centerline{Max. = HJD\,2450117.597  +  3\fd 2951 $\times$ E}
 \hspace*{7.1cm}$\pm$0.004  $\pm$\ \,0.0008
\vskip 1mm

Photographic archival plates stored at various observatories should be 
analysed to refine
the above given ephemeris, as well as reconstruct  the past years' light curve of this new cepheid.
\vskip 1cm

\beginauthors
Francisco CAMPOS-CUCARELLA          
Joan GUARRO-FLO                  
Josep M. GOMEZ-FORRELLAD            
Grup d'Estudis Astronomics         
Apartado 9481                     
08080 Barcelona                     
Spain                               
e-mail: jmgomez@astro.gea.cesca.es
\authorsrightcol
Enrique GARCIA-MELENDO
Esteve Duran Observatory
El Montanya - Seva
08553 SEVA
Barcelona
Spain
e-mail: duranobs@astro.gea.cesca.es
\vskip 6mm
\endauthors


\references

Bastian, U., 1995, {\it Sterne und Weltraum}, No.\,10, 724

Born, E., 1995, {\it BAV Rundbrief}, {\bf 44}, No.\,4, 155

Makarov, V., Bastian U., Hoeg, E., Grossmann, V. and Wicenec, A., 1994,
 {\it IBVS}, No.\,4118.
 

\end{document}
