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\IBVShead{5347}{2 December 2002}

\IBVStitletl{Photometry of OW G\lowercase{em}}

\IBVSauth{Kaiser, D.H.$^1$; Henden, A. A.$^2$; Dvorak, S.$^3$; Garcia-Melendo, E.$^4$; Gomez-Forrellad, J. M.$^5$; Howell, J. A.$^6$; Koff, R. A.$^7$; Kuebler, P.$^8$; Lubcke, G. C.$^9$; Martin, B.$^{10}$; Nelson, R. H.$^{11}$; Pullen, A. C.$^{12}$; Terrell, D.$^{13}$; West, D.$^{14}$; Williams, D. B.$^{15}$; Wolf, G. W.$^{16}$; Zissell, R. E.$^{17}$}

\IBVSinst{2631 Washington St., Columbus, Indiana 47201; USA, e-mail: dhkaiser@sprynet.com}

\IBVSinst{Universities Space Research Association/U.S. Naval
Observatory, P.O. Box 1149, Flagstaff,  AZ 86002-1149,
USA; e-mail: aah@nofs.navy.mil}

\IBVSinst{Rolling Hills Observatory, 1643 Nightfall Dr., Clermont, Florida 34711, USA; e-mail: sdvorak@cfl.rr.com}

\IBVSinst{Esteve Duran Observatory Foundation, Montseny 46, El Montanya, 08553 Seva, Barcelona, Spain; \\ e-mail: duranobs@astrogea.org}

\IBVSinst{Esteve Duran Observatory Foundation, Montseny 46, El Montanya, 08553 Seva, Barcelona, Spain; \\ e-mail: jmgomez@astrogea.org}

\IBVSinst{3522 NW 18th Avenue, Gainesville, FL 32605, USA; e-mail: astrogator@mindspring.com}

\IBVSinst{980 Antelope Drive West, Bennett, Colorado 80102, USA; e-mail: bob.koff@tds.net}

\IBVSinst{1550 Blackstone Drive, Columbus, OH 43235; e-mail: pkueb@aol.com}

\IBVSinst{3817 Patrick Henry Way, Middleton, Wisconsin 53562, USA; e-mail: gil2@ix.netcom.com}

\IBVSinst{The King's University College, 9125-50th Street, Edmonton, Alberta T6B 4H3, Canada; \\ e-mail: bmartin@kingsu.ab.ca}

\IBVSinst{1393 Garvin Street, Prince George, BC, Canada, V2M 3Z1; e-mail: bob.nelson@shaw.ca}

\IBVSinst{10215 Davis Road, P.O.Box 930, Wilton, California 95693, USA; e-mail: cpullen@pacsafe.com}

\IBVSinst{Dept. of Space Studies, Southwest Research Institute,
1050 Walnut St., Suite 426, Boulder CO 80302, USA;
e-mail: terrell@boulder.swri.edu}

\IBVSinst{P.O. Box 517, Derby, KS 67037, USA;
e-mail:dwest61506@aol.com}

\IBVSinst{P. O. Box 58, Whitestown, Indiana 46075, USA; e-mail: dbwilyumz@aol.com}

\IBVSinst{SW Missouri State University, Dept. Physics, Astronomy and Materials Science, Springfield, MO 65804, USA; e-mail: georgewolf@smsu.edu}

\IBVSinst{Williston Observatory, Mount Holyoke College, South Hadley, MA 0175, USA; \\ e-mail: rzissell@mhc.mtholyoke.edu}

\IBVSabs{We report on the eclipses of OW Gem}

\SIMBADobj{OW Gem}

\IBVStyp{ EB }


\begintext

\vspace*{-0.5cm}

Variability of the long period eclipsing binary OW Geminorum (= HDE~258878 = 
BD+17\deg 1281, spectral type F2 Ib-II, $V_{\rm max}$=8\fmm22) was discovered by Kaiser in 1988 while conducting a photographic nova patrol (Kaiser et al. 1988).  Kaiser (1988) also determined the system's long period of 1258 days.  Williams (1989) discovered the high eccentricity.  Griffin and Duquennoy (1993) have given a thorough report based on radial velocity studies.

Four primary eclipses have occurred since discovery; three have published 
observations, either visual or photometric (Williams and Kaiser 1991; Pravec 
1992; Hanzl et al. 1993; Hager 1996; Derekas et al. 2002).  Unfortunately, 
coverage was sparse due to longitudinally limited observing sites or solar 
conjunction.  The secondary eclipse has had extremely little coverage published, consisting of three photoelectric observations from Williams (Williams 1989).\\

\vspace*{-0.5cm}

The AAVSO's eclipsing binary team has conducted a multi-filtered international campaign on OW Gem covering the primary and secondary eclipses in 1995 and 2002. Henden used the USNO 1.0-m telescope with a SITe 1024 $\times$ 1024 thinned, backside illuminated CCD and standard Johnson-Cousins standard $UBV(RI)_{c}$ filters along with Landolt standards to determine standard magnitudes for the variable and the comparison stars.  These data are in Table 1 with all errors under 0.01 mag.  GSC~1332.0564 was used as the 
comparison and GSC~1332.0578 as the check star for all four eclipses. Derekas et al. (2002) reported possible variability in GSC~1332.0564, although we do not see this in our data.

{\small
\begin{table}
\centerline{{\small Table 1. Standard magnitudes and color indices, Henden }}
\begin{center}
\begin{tabular}{ccccccc}
\hline
Star & GSC & $V$ & $B-V$ & $U-B$ & $V-R_{c}$ & $R_{c}-I_{c}$ \\ \hline
var max & 1332.0490 & 8.217 & 0.689 & 0.437 & 0.418 & 0.433 \\
var primary min & 1332.0490 & 9.673 & 1.005 & 0.619 & 0.589 & 0.595 \\
var secondary min & 1332.0490 & 8.317 & 0.646 & 0.420 & 0.390 & 0.409 \\
comp & 1332.0564 & 9.004 & 0.239 & 0.065 & 0.148 & 0.158 \\
check & 1332.0578 & 9.900 & 0.325 & 0.006 & 0.204 & 0.206 \\ \hline
\end{tabular}
\end{center}
\end{table}
}


{\small
\begin{table}
\centerline{{\small Table 2. Observers and equipment used }}
\begin{center}
\begin{tabular}{ccccc}
\hline
Observer & Telescope & CCD/Photometer & Filter(s) & Campaign \\ \hline
DHK & 0.35-m & ST-9E & $BVR_{c}$ & '95 p, '02 ps\\
AAH & 1.00-m & SITe Tektronix & $UBV(RI)_{c}$ & '02 ps \\
SD & 0.20-m & ST-9E & $V$ & '02 s \\
EGM & 0.20-m & Starlight Express & $V$ & '02 p \\
JGF & 0.10-m, 0.41-m & Starlight Express & $V$ & '02 ps \\
JAH & 0.45-m & ST-9E & $V$ & '02 p \\
RAK & 0.25-m & ST-6 & $BV(RI)_{c}$ & '02 p \\
PK & 0.35-m & FLI & $V$ & '02 p \\
GCL & 0.27-m & ST-9E & $V(RI)_{c}$ & '02 p \\
ACP & 0.27-m & ST-6 & $BV(RI)_{c}$ & '02 p \\
DT & 0.40-m, 0.60-m & Photometrics CCD, ST-8 & $V$ & '95 p, '02 p \\
DW & 0.20-m & ST-9E & $V$ & '02 ps \\
REZ & 0.60-m & Photometrics CCD & $BV(RI)_{c}$ & '95 ps, '02 p \\
DBW & 0.90-m & SSP-3 & $V$ & '95 p \\
BM & 0.20-m & Lynxx & $V$ & '95 p \\
GWW & 0.40-m & Photometrics CCD & $V$ & '95 p \\ \hline
\end{tabular}
\end{center}
\end{table}
}

\large

Photometric data about all stars within 5 arcmin of the variable are available at {\tt ftp://ftp.nofs.navy.mil/pub/outgoing/aah/sequence/owgem.dat}. Sixteen observers from two continents participated in the campaigns, see Table 2.

Results of the campaigns are listed in Table 3. Primary times of minimum were determined with the software $AVE$ (Barbera 2000) based on the Kwee and Van Woerden method (Kwee-van Woerden 1956). Using a Fourier curve-fitting technique, Nelson determined the time of secondary minimum. Light curves for all eclipses are found in Figures~1-4.

The primary minima are consistent with the light elements given below, which are from Williams and Kaiser (1991).  The secondary minimum occurs at phase 0.232 using the same elements.  A full model of OW Geminorum will be published elsewhere.

\[
\begin{array}{r@{}r@{}l}
{\rm Min.~I = HJD~} 2415779.0 & {} + 1258\fday59 & {} \times E. \ 
\end{array}
\]


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{\normalsize
\begin{table}
\centerline{{\normalsize Table 3. Times of minimum }}
\begin{center}
\begin{tabular}{cc}
\hline
Eclipse & Time of minimum (error) \\ \hline
1995 primary & 2449760.59 (2) \\
1995 secondary & 2450053.2 (2) \\
2002 primary & 2452277.77 (1) \\
2002 secondary & 2452570.9 (1) \\ \hline
\end{tabular}
\end{center}
\end{table}
}

\large

DT wishes to acknowledge the continued support of Keith Gleason at Sommers-Bausch Observatory for a generous allocation of time on the SBO 24-inch for this and other binary star projects.

\references

Barbera, R., AVE software (V2.5), {\tt http://www.astrogea.org}

Derekas, A., Kiss, L. L., Szab\'o, Gy. M., F\H ur\'esz, G., S\'arneczky, K., Heiner, Zs.,  2002, {\it IBVS}, No.\,5239

Griffin, R. F., Duquennoy, A., 1993, {\it The Observatory}, {\bf 113}, 53

Hager, T., 1996, {\it JAAVSO}, {\bf 24}, No.\,1, 9

Hanzl, D., Papousek, J., Chochol, D., Pravec, P., 1993, {\it IBVS}, No.\,3821

Henden, A. A., 2000, \,{\tt ftp://ftp.nofs.navy.mil/pub/outgoing/aah/sequence/owgem.dat} 

Kaiser, D. H., Baldwin, M. E., Williams, D. B., 1988, {\it IBVS}, No.\,3196 

Kaiser, D. H., 1988, {\it IBVS}, No.\,3233

Kwee, K. K., and Van Woerden, H., 1956, {\it BAN}, {\bf 12}, 327

Pravec, P., 1992, {\it IBVS}, No.\,3793

Williams, D. B., 1989, {\it JAAVSO}, {\bf 18}, 7

Williams, D.B., Kaiser, D.H., 1991, {\it JAAVSO}, {\bf 20}, 231


\endreferences


\IBVSedata{5347-t4.txt}

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