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\input ibvs2.sty
\begin{document}

\IBVShead{5546}{30 July 2004}

\IBVStitle{GSC 3449-0688 - A New Solar-Type Overcontact Binary }

\IBVSauth{Nelson, Robert H.$^{1,2}$; Henden, Arne A.$^3$; Krajci, T.$^4$}

\IBVSinst{1393 Garvin Street, Prince George, BC, Canada, V2M 3Z1; e-mail: bob.nelson@shaw.ca}
\IBVSinst{Guest User, Canadian Astronomy Data Centre, which is operated by the Dominion Astrophysical Observatory for the National Research Council of Canada's Herzberg Institute of Astrophysics.}
\IBVSinst{Universities Space Research Association/U.S. Naval Observatory, P.O.Box 1149, Flagstaff, Arizona 86002-1149, USA, e-mail: aah@nofs.navy.mil}

\IBVSinst{3933 Stockton Loop, S. E., Albuquerque, NM.  87116, U.S.A., loukrajci@comcast.net} %email

\SIMBADobj{GSC 3449-0688}

\begintext

GSC 3449-0688 (10\hr 45\mm 15\sec +52\deg 16\arcm 49\arcs, 2000.0) was discovered to be variable by RHN on 2004 February 18 during filtered CCD observations of nearby BH UMa.  Further CCD observations by RHN and TK over the next few nights and into March quickly established a period.  Table 1 contains all the available times of minimum and deviations from the best fit linear relation.

\begin{table}[!hb]
\centerline{Table 1.  Observed minima of GSC 3449-0688}
\begin{center}
\begin{tabular}{|c|c|c|c|c|c|}
\hline
HJD - 2400000&Error&Type&Cycle&$O-C$ (days)&Observer\\
\hline
53053.804&0.01&I&$-$3&$-$0.002&Nelson\\
53053.974&0.01&II&$-$2.5&$-$0.004&Nelson\\
53054.8371&0.0001&I&0&0.0000&Nelson\\
53055.3529&0.0003&II&1.5&0.0000&Krajci\\
53055.5253&0.0002&I&2&0.0005&Krajci\\
53057.7602&0.0002&II&8.5&0.0003&Nelson\\
53057.9317&0.0002&I&9&$-$0.0001&Nelson\\
53058.9635&0.0002&I&12&0.0001&Nelson\\
53059.6509&0.0010&I&14&$-$0.0002&Nelson\\
53066.8716&0.0006&I&35&$-$0.0006&Nelson\\
53067.0450&0.0006&II&35.5&0.0009&Nelson\\
53074.7807&0.0003&I&58&$-$0.0002&Nelson\\
53074.9528&0.0003&II&58.5&$-$0.0001&Nelson\\
53077.7032&0.0003&II&66.5&$-$0.0005&Nelson\\
53077.8758&0.0002&I&67&0.0001&Nelson\\
\hline
\end{tabular}
\end{center}
\end{table}

The following elements were determined (where the numbers in brackets are the errors in the units of the last digit):
$${\rm JD\ Hel\ Min\ I} = 53054.8371(1) + 0.343854(4) {\rm E}$$
A total of 135 and 162 observations in V and Rc respectively was made by RHN at the Sylvester Robotic Observatory (see Nelson 2002b).  They were reduced using MIRA by Axiom Research (for Windows; this platform was used by Nelson throughout his part of the study), in the usual way (ibid).

Henden (2004) used the USNO Flagstaff Station 1.0-m. telescope equipped with a SITe/Tektronix 1024$\times$1024 CCD to observe the field in the standard Johnson-Cousins BVRcIc passbands on several photometric nights, using Landoldt standards to calibrate the field.  Astrometry is based on USNO-A 2.0 and has errors less than 100mas internal error.  Comparison and check stars were standardized as follows in Table 2:


\begin{table}
\centerline{Table 2.  Positions and magnitudes}
\normalsize
\begin{center}
\begin{tabular}{|c|c|c|c|c|c|c|c|c|c|}
\hline
Star&GSC&RA&Dec&V&Error&$B-V$&Error&$V-R$&Error\\
&3449-&HH.MMSSss&DD.MMSSs&mag&mag&mag&mag&mag&mag\\
\hline
Variable&0688&10.451472&52.16485&13.686&0.242&0.640&0.002&0.400&0.005\\
Comp&0707&10.453084&52.10144&11.590&0.018&0.681&0.005&0.366&0.008\\
Check&0726&10.451102&52.12136&13.103&0.006&0.547&0.016&0.319&0.006\\
\hline
\end{tabular}
\end{center}
\end{table}


Assuming no interstellar reddening (a reasonable assumption at the galactic latitude of 55 degrees) and main sequence stars, a colour index of $B-V$ = 0.64 implies a spectral type of G3 and a $\log g$ value of 4.444 (cgs units, Allen, 1973), and a primary temperature T1 = 5751 K (Flower, 1996).

The photometric data were analyzed by the Wilson Devinney (WD) light curve 
analysis program (Wilson and Devinney, 1971, Wilson, 1990) using an interface 
program, `WDWint' written by the author (see Nelson, et al., 2002b).  
The general appearance of the curve suggested an overcontact binary; hence mode
 3 was chosen.  The following settings were selected: convective envelopes (appropriate for solar-type stars), giving albedos of A1 = A2 = 0.5 and gravity exponents of g1 = g2 = 0.32 and the logarithmic (LD=2) limb darkening law, 
appropriate for cooler stars (Bessell, 1979). Limb darkening values were 
found from a program by Terrell (1994) that interpolates from van Hamme's tables (van Hamme, 1993).  Black body radiation was used initially, but later runs employed the atmosphere option of WD taken from the Carbon and Gingerich atmospheres (Carbon \& Gingerich, 1969).


After a best-fit solution was found, third light was tested for and the predicted correction less than the estimated error.  Therefore third light may be ruled out.  The final values are given in Table 3, the final light curves are plotted in Figure 1, and a 3-D representation at phase 0.25 generated by Binary Maker 3-D (Bradstreet, 1993) is shown in Figure 2.


\begin{table}
\centerline{Table 3.  Solution parameters}
\begin{center}
\begin{tabular}{|c|c|c|c|c|c|c|}
\hline
Quantity&\multicolumn{2}{c|}{Value}&Error&Quantity&Value&Error\\
&Star 1&Star 2&&&&\\
\hline
F&1.000&1.000&[fixed]&q = M2/M1&0.331&0.003\\
g&0.320&0.320&[fixed]&i (deg)&81.2&0.4\\
A&0.500&0.500&[fixed]&L1/(L1+L2)  (V)&0.704&0.003\\
x (bol)&0.138&0.138&[fixed]&L1/(L1+L2)  (Rc)&0.708&0.003\\
y (bol)&0.636&0.636&[fixed]&$\varphi_0$&0.005&0.0003\\
x (V)&0.550&0.550&[fixed]&e&0&0.002\\
y (V)&0.254&0.254&[fixed]&r1 (pole)&0.453&0.002\\
x (Rc)&0.653&0.653&[fixed]&r1 (side)&0.487&0.003\\
y (Rc)&0.138&0.138&[fixed]&r1 (back)&0.514&0.002\\
T1 (K)&5751&&[fixed]&r2 (pole)&0.273&0.003\\
T2 (K)&&5921&14&r2 (side)&0.285&0.004\\
$\Omega$&2.510&2.510&0.009&r2 (back)&0.232&0.006\\
f (fill factor)&0.12&0.12&0.03&$\Sigma\ \omega_{\rm res}^2$&0.0266&na\\
\hline
\end{tabular}
\end{center}
\end{table}


\IBVSfig{9cm}{5546-f1.eps}{}
\IBVSfigKey{5546-f1.eps}{GSC 3449-0688}{light curve}

\IBVSfig{10cm}{5546-f2.eps}{}
\IBVSfigKey{5546-f2.eps}{GSC 3449-0688}{}


\IBVSedata{5546-t4.txt}
\IBVSdataKey{5546-t4.txt}{BH UMa}{sequence}
\AladinChart{5546-t4}
\IBVSecomment{BH UMa photometric sequence}


{\bf Acknowledgements:}

Thanks are due to Environment Canada for the website satellite images (see `Satellite images' below) that were essential in predicting clear times for observing runs in this cloudy locale and to Attila Danko for his Clear Sky Clocks, (see below).

		

\newpage
\references

Allen, C.W., 1973, {\it Astrophysical Quantities}, (Univ. of London Press)

Bessell, M.S., 1979, {\it PASP}, {\bf 91}, 589

Bradstreet, D.H., 1993, {\it ``Binary Maker 2.0 - An Interactive Graphical Tool for Preliminary Light Curve Analysis"}, in Milone, E.F. (ed.) Light Curve Modelling of Eclipsing Binary Stars,  pp 151-166 (Springer, New York)

Carbon, D.F. and Gingerich, O., 1969, in Theory and Observation of Normal Stellar Atmospheres, ed. O. Gingerich, Cambridge, MA, MIT U. Press, p 377

Danko, A., Clear Sky Clocks, {\tt http://cleardarksky.com/}

Flower, P., 1996, {\it ApJ}, {\bf 469}, 355

Henden, A.A., 2004, {\tt ftp://ftp.nofs.navy.mil/pub/outgoing/aah/sequence/bhuma.dat}

Nelson, R.H., 2002a, {\it IBVS}, 5493

Nelson, R.H., Robb, R.M., Kaiser, D.H., and Billings, G.B., 2002b, {\it IBVS}, 5285

Satellite images for North America, {\tt http://www.cmc.ec.gc.ca/cmc/htmls/satellite.html}

van Hamme, 1993, {\it AJ}, {\bf 106}, 2096

Wilson, R.E., and Devinney, E.J., 1971, {\it ApJ}, {\bf 166}, 605

Wilson, R.E., 1990, {\it ApJ}, {\bf 356}, 613

\endreferences 

\end{document}


