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

\begin{document}

\IBVShead{5547}{30 July 2004}

\IBVStitletl{Preliminary Solutions for the Eclipsing Binaries}{ ROTSE1 J180616.31+280109.1, V883~H\lowercase{er}, V507~L\lowercase{yr}, MQ~P\lowercase{eg}, and MX~P\lowercase{eg}}

\IBVSauth{Wetterer, C. J.$^1$; Bloomer, R. H.$^2$; Carlson, E.$^1$; Dougherty, M. S.$^1$; Olive, D.$^3$; Crawford, B.$^2$; Cox, S.$^4$; Fletcher, K.$^5$; Kunkle, R.$^6$}

\IBVSinst{United States Air Force Academy, USAF
Academy, CO 80840, USA, e-mail: charles.wetterer@usafa.edu}

\IBVSinst{King College, Bristol, TN 37620, USA, e-mail: rhbloome@king.edu}

\IBVSinst{Carson Newman College, Jefferson
City, TN 37760, USA, e-mail: olivejr@cn.edu}

\IBVSinst{Warren Wilson College, Ashville, NC 28815, USA}

\IBVSinst{Emory and Henry College, Emory ,VA 24327, USA}

\IBVSinst{Albuquerque
Technical Vocational Institute, Albuquerque, NM 87109, USA,
e-mail: jkunkle@tvi.edu}

\SIMBADobj{ROTSE1 J180616.31+280109.1} 
\SIMBADobj{V883 Her}
\SIMBADobj{V507 Lyr} 
\SIMBADobj{MQ Peg} 
\SIMBADobj{MX Peg}
\GCVSobj{V883 Her}
\GCVSobj{V507 Lyr} 
\GCVSobj{MQ Peg} 
\GCVSobj{MX Peg}

\IBVSabs{Results of photometry on five W~UMa eclipsing variable
stars previously discovered in the CCD/Transit Instrument (CTI)
survey are reported.  These variables were part of a Consortium
for Astronomy Research and Teaching (CART) summer project at the
US Air Force Academy (USAFA) Observatory and follow-up independent
cadet study.}

\begintext

\IBVSEstarlis{
ROTSE1 J180616.31+280109.1 & EW  & 18\hr 06\mm 16\fsec3 & $+$28\deg 01\arcm 09\arcs & CTI catalog \\
V883~Her & EW   & 17\hr 50\mm 46\fsec5 & $+$28\deg 00\arcm 49\arcs & CTI catalog \\
V507~Lyr & EW   & 18\hr 40\mm 48\fsec5 & $+$28\deg 01\arcm
38\arcs & CTI catalog \\
MQ~Peg   & EW   & 22\hr 48\mm 10\fsec4 & $+$28\deg 05\arcm
19\arcs & CTI catalog \\
MX~Peg   & EW   & 23\hr 22\mm 15\fsec0 & $+$28\deg 05\arcm
33\arcs & CTI catalog \\}

\IBVSTobs{CCD Transit Instrument (CTI), 1.8-m f/2.2 meridian pointing telescope \\
Capilla Peak Observatory (CAP), 0.61-m f/15.2 Cassegrain telescope \\
US Air Force Academy Observatory (AFA), 0.61-m f/15.6 Cassegrain
telescope}

\IBVSTdet{CTI: RCA LN2-cooled CCD, 320 $\times$ 512 pixels,
8\farcm3 \ wide strip, CAP: RCA LN2-cooled CCD, 320 $\times$ 512
pixels, 3\farcm6 \ $\times$ 5\farcm2 \ FOV, AFA: Photometrics
LN2-cooled CCD, 512 $\times$ 512 pixels, 3\farcm6 \ $\times$
3\farcm6 \ FOV.}

\IBVSTfil{CTI: $BVR$, CAP: $V$, AFA: $BVR$}

\IBVSTdateobs{CTI: 1987.10--1991.05, CAP: 1994.06--1996.10, AFA:
2003.06--2003.09}


ROTSE1 J180616.31+280109.1 (hereafter J180616) previously
discovered in the ROTSE test field (Akerlof et al. 2000) and
recently identified during a new search for variable stars in the
CCD/Transit Instrument (CTI) databases, along with four other
W~UMa stars identified by Wetterer et al. 1996 (hereafter W96) in
the CTI survey (V883~Her, V507~Lyr, MQ~Peg, and MX~Peg) were
chosen for observations as part of a Consortium for Astronomy
Research and Teaching (CART) summer project at the US Air Force
Academy (AFA) Observatory and follow-up independent cadet study of
modeling W~UMa eclipsing systems.  The CTI data and 1994 CAP data
for V883~Her, V507~Lyr, MQ~Peg, and MX~Peg were previously
used in the photometric analysis in W96.\\

\begin{table}[h]
\centering \caption{Photometric Characteristics}
\normalsize
\begin{tabular}{llllll} \hline\hline
           &  J180616       & V883~Her       & V507~Lyr       & MQ~Peg         & MX~Peg \\
$V_{Max}$  & 12.737(2)      & 13.146(3)      & 14.266(3)      & 13.434(4)      & 16.326(13) \\
$V_{MinP}$ & 13.151(1)      & 13.355(6)      & 14.720(6)      & 13.694(5)      & 16.611(6) \\
$V_{MinS}$ & 13.039(1)      & 13.323(5)      & 14.689(7)      & 13.685(8)      & 16.587(8) \\
$V_{Mean}$ & 12.875(1)      & 13.224(1)      & 14.422(1)      & 13.539(1)      & 16.056(10) \\
$(B-V)$    &  0.414(12)     &  0.412(10)     &  0.57(6)       &  0.502(5)      &  0.63(5) \\
$(V-R)$    &  0.255(3)      &  0.257(6)      &  0.379(21)     &  0.314(3)      &  0.44(6) \\
$E(B-V)$   &  0.100         &  0.061         &  0.181         &  0.061         &  0.063  \\
period     & 0.6600655(20)  & 0.695016(3)    & 0.3669098(10)  & 0.3793826(15)  & 0.3943902(20) \\
epoch      & 52906.674(4)   & 52843.788(7)   & 52865.694(5)   & 52901.8527(23) & 52872.955(8) \\
\hline\hline
\end{tabular}
\end{table}

Photometric characteristics for these stars are listed in Table 1:
$V_{Max}$, $V_{MinP}$, and $V_{MinS}$ are the average standard V
magnitudes at maximum, primary minimum, and secondary minimum
light (CAP and AFA magnitudes transformed to CTI instrumental
magnitudes via differential photometry with nearby stars in CTI
database and then to standard magnitudes as detailed in W96);
$V_{Mean}$ is the flux averaged standard V magnitude; $(B-V)$ and
$(V-R)$ are the standard colors (recalculated from all available
CTI and AFA data); $E(B-V)$ is reddening (as estimated from HI
maps in Burstein and Heiles 1982); period is in days (using V
photometry and employing Lafler and Kinman's period finding
algorithm (Lafler and Kinman 1965)); and epoch is HJD - 2400000 of
latest primary minima measured.  Observations of all stars were
planned to fill in the light curve and not necessarily measure a
minimum timing.  For those nights where a minimum was adequately
observed, however, the Kwee and Van Woerden method (Kwee and Van
Woerden 1956) was used to measure the minimum's timing.  This is
not possible for the CTI data because CTI observed each star only
once per night, however, approximate minima timings can be listed
for CTI data (and poorly covered CAP data) by listing the most
prominent darkenings (within 10 percent of the known minimum
magnitude and given a standard 0.02 day uncertainty). All
these minima timings are listed in Table 3. \\

We used the Binary Star Maker 2.0 software and reference manual
(Bradstreet 1993) to obtain preliminary solutions for these
eclipsing binaries.  By examining the most precise photometry (CAP
1996) V507~Lyr appears to undergo a total eclipse with a broadened
secondary eclipse and a rounded and slightly deeper primary
eclipse.  For this system, we used the measured $B-V$ color to
determine surface temperature, and assumed identical temperatures
for the primary and secondary. The uncertainty in temperature was
determined from the uncertainty in $B-V$ color.  We simultaneously
adjusted the mass ratio, fillout factor, and inclination to
reproduce the observed light curve and list the best fit values and
ranges qualitatively estimated by examining model fits. The other
four systems appear to have rounded and smoothly varying
light curves characteristic of W~UMa eclipsing binaries undergoing
partial eclipses.  For these systems, we used the measured $B-V$
color and eclipse depths to estimate surface temperatures and
calculated mass ratios consistent with equivalent temperature
stars on the Main Sequence.  This is probably a good assumption
for MQ~Peg and MX~Peg whose light curve, color, and period are
consistent with a contact system with stellar radii approximately
equal to the equivalent Main Sequence stars.  The observed colors
and longer periods of J180636 and V883~Her, however, suggest that
one or both components in these systems are extended stars (radii
40-50 percent greater than Main Sequence equivalents).  Given the
above assumptions, two uncertainties in temperature were
determined: the first from the uncertainties in eclipse depths and
the second from the uncertainty in the corrected $B-V$ color. Again,
given the above assumptions, the uncertainty in mass ratio was
determined from the uncertainties in eclipse depths only (the
effect of the uncertainty in the $B-V$ color on the mass ratio is
negligible). We simultaneously adjusted the fillout factor and
inclination to reproduce the observed light curve and list the best
fit value and ranges qualitatively estimated by examining model
fits. We modeled all stars using standard values for gravity
darkening coefficients (1.00 for radiative stars of T $>$ 7200 K
and 0.32 for convective stars), limb darkening coefficients (from
Appendix III in Bradstreet 1993) and reflection coefficients (1.0
for radiative stars and 0.5 for convective stars) and assumed
there was no third light contribution.  Table 2
summarizes the results. \\

\begin{table}[h]
\centering \caption{Preliminary Solutions}
\normalsize
\begin{tabular}{llllll} \hline\hline
              & J180616                  & V883~Her                 & V507~Lyr                 & MQ~Peg                   & MX~Peg \\
$T_{P}$ (K)   & 7390 $\pm$ 40,70         & 7110 $\pm$ 130,60        & 6800 $\pm$ 260           & 6535 $\pm$ 60,20         & 6130 $\pm$ 80,180  \\
$T_{S}$ (K)   & 5900 $\pm$ 40,60         & 6720 $\pm$ 130,60        & 6800 $\pm$ 260           & 6480 $\pm$ 60,20         & 5990 $\pm$ 80,180  \\
$mass ratio$  & 0.621 $\pm$ 0.007        & 0.876 $\pm$ 0.033        & 0.24 $\pm$ 0.01          & 0.984 $\pm$ 0.017        & 0.959 $\pm$ 0.022  \\
$fillout$     & 0.1 (0.0 - 0.3)          & 0.1 (0.0 - 0.15)         & 0.2 (0.1 - 0.4)          & 0.1 (0.0 - 0.35)         & 0.0 (0.0 - 0.1) \\
$inclination$ & 66\deg (68\deg - 64\deg) & 54\deg (56\deg - 53\deg) & 80\deg (84\deg - 76\deg) & 59\deg (61\deg - 51\deg) & 62\deg (62\deg - 60\deg)      \\
\hline\hline
\end{tabular}
\end{table}

\begin{table}[h]
\centering \caption{Minima Timings}
\begin{tabular}{llll} \hline\hline
HJD               & type       & HJD              & type \\
\textbf{J180616}  &           & 2452842.7594(28)& secondary\\
2447320.852(20)  & secondary  & 2452843.860(10) & secondary\\
2447322.856(20)  & secondary  & 2452844.7772(27)& primary\\
2447323.844(20)  & primary    & 2452864.779(5)  & secondary\\
2447643.965(20)  & primary    & 2452865.694(5)  & primary\\
2447688.845(20)  & primary    & 2452878.721(6)  & secondary\\
2447100.719(20)  & primary    & 2452884.776(9)  & primary\\
2448101.717(20)  & secondary  & \textbf{MQ~Peg}\\
2452830.760(12)  & primary    & 2447443.715(20) & primary\\
2452833.732(19)  & secondary  & 2447466.651(20) & secondary\\
2452834.719(12)  & primary    & 2447470.640(20) & primary\\
2452866.7340(25) & secondary  & 2447482.606(20) & secondary\\
2452906.674(4)   & primary    & 2447807.718(20) & secondary\\
\textbf{V883~Her} &           & 2449545.859(20) & primary \\
2447319.844(20)  & primary    & 2449952.920(20) & primary\\
2447357.742(20)  & secondary  & 2450036.5601(15)& secondary\\
2447678.861(20)  & secondary  & 2450036.7566(20)& primary\\
2447679.858(20)  & primary    & 2450041.6865(18)& primary\\
2447686.840(20)  & primary    & 2452864.861(5)  & secondary\\
2448062.811(20)  & primary    & 2452865.813(4)  & primary\\
2448100.709(20)  & secondary  & 2452866.760(6)  & secondary\\
2448381.907(20)  & secondary  & 2452871.691(9)  & secondary\\
2449528.907(20)  & secondary  & 2452871.882(5)  & primary\\
2449611.637(20)  & secondary  & 2452878.710(4)  & primary\\
2450228.796(5)   & secondary  & 2452894.644(4)  & primary\\
2450229.8298(25) & primary    & 2452894.828(9)  & secondary\\
2452842.745(9)   & secondary  & 2452901.6607(14)& secondary\\
2452843.788(7)   & primary    & 2452901.8527(23)& primary\\
2452844.834(17)  & secondary  & 2452907.733(7)  & secondary\\
\textbf{V507~Lyr} &            & \textbf{MX~Peg}  &\\
2447293.948(20)  & secondary  & 2447466.673(20) & primary\\
2447323.867(20)  & primary    & 2447482.630(20) & secondary\\
2447680.889(20)  & primary    & 2447500.581(20) & primary\\
2447682.883(20)  & secondary  & 2448126.865(20) & primary\\
2448062.845(20)  & primary    & 2448212.631(20) & secondary\\
2448391.941(20)  & primary    & 2449610.747(20) & secondary\\
2449538.922(20)  & primary    & 2449634.804(9)  & secondary\\
2450218.8071(22) & primary    & 2452872.758(8)  & secondary\\
2452838.725(16)  & secondary  & \\
\hline\hline
\end{tabular}
\end{table}

Notes on individual stars: \\

\textbf{J180616} is listed in Akerlof et al. 2000 as a W~UMa
eclipsing system with a period of 0.65998(23) days. The best
period determined using the CTI and AFA V data is 0.6600655(20)
days.  There is evidence of possible star spot activity in the AFA
photometry (see phases 0.6 to 0.9 in Figure 1) where a single
night of V observations was approximately 0.05 magnitudes
fainter than during other observations. \\

\textbf{V883~Her}'s period is listed in W96 (using previously
reported CTI and CAP (1994) V data) as 0.695000(3) days
(uncertainty originally not published). The new CAP (1996) V data
slightly modifies this period to 0.695002(3) days. The new AFA V
data, however, is systematically shifted later by about 1.1 hours.
The best period determined using the new CAP (1996) and AFA V data
is 0.695016(3) days with now the CTI data offset. No systematic
timing error is known in any of the data, and so this may indicate
that V883~Her's period is changing. If real, this implies a period
increase of about 8.6 $\pm$ 2.3 seconds/century. This is
extraordinarily large, but of the same order of magnitude as some
other W~UMa stars (see Molik and Wolf 1998). Clearly further more
precise observations are warranted. Using the latter period and
the minima listed in Table 3, the $O-C$
plot in Figure 6a illustrates this possible period increase. \\

\textbf{V507~Lyr}'s period is listed in W96 as 0.366912(1) days.
The new CAP (1996) V data fits this period well while the new AFA
V data is systematically shifted, this time earlier by about 15
minutes.  The best period determined by CAP and AFA V data is
0.3669098(10) days.  Again, if real, this implies a period
decrease of about 1.0 $\pm$ 0.8 seconds/century. Using the latter
period and the minima listed in Table 3, the $O-C$ plot in Figure 6b
illustrates this possible period decrease. \\

\textbf{MQ~Peg}'s period is listed in W96 as 0.379380(3) days. The
new CAP (1995) V data refines this slightly to 0.3793785(15) days.
The new AFA V data is again systematically shifted, this time
later by about 30 minutes.  The best period determined by CAP and
AFA V data is 0.3793826(15) days.  Again, if real, this implies a
possible period increase of about 2.2 $\pm$ 1.1 seconds/century.
Using the latter period and the minima listed
in Table 3, the $O-C$ plot in Figure 6c illustrates this possible period increase. \\

\textbf{MX~Peg}'s period is listed in W96 as 0.394387(3) days. The
new CAP (1996) V data and AFA V data refined this slightly to 0.3943902(20) days. \\


\IBVSTack{We thank the Appalachian College Association for their
support of this research.  This research made use of the SIMBAD
database, operated at CDS, Strasbourg, France.}


\references

Akerlof, C. et al., 2000, {\it AJ}, {\bf 119}, 1901.

Bradstreet, 1993, {\it Binary Star Maker 2.0}, Contact Software.

Burstein, D., and Heiles, C., 1982, {\it AJ}, {\bf 87}, 1165.

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

Lafler, J. and Kinman, T. 1965, {\it ApJ Sup.}, {\bf 11}, 216.

Molik, P. and Wolf, M. 1998, {\it IBVS}, No. 4640.

Wetterer, C.J., McGraw, J.T., Hess T.R., and Grashuis, R., 1996,
{\it AJ}, {\bf 112}, 742.

\endreferences

\IBVSfig{50mm}{5547-f1.eps}{Light curve for J180616: P = 0.6600655 days,
epoch = 2452906.674 HJD}
\IBVSfigKey{5547-f1.eps}{ROTSE1 J180616.31+280109.1}{light curve}

\IBVSfig{50mm}{5547-f2.eps}{Light curve for V883~Her: P = 0.695016 days,
epoch = 2452843.788 HJD}
\IBVSfigKey{5547-f2.eps}{V883 Her}{light curve}

\IBVSfig{50mm}{5547-f3.eps}{Light curve for V507~Lyr: P = 0.3669098
days, epoch = 2452865.694 HJD}
\IBVSfigKey{5547-f3.eps}{V507 Lyr}{light curve}

\IBVSfig{50mm}{5547-f4.eps}{Light curve for MQ~Peg: P = 0.3793826 days,
epoch = 2452901.8527 HJD}
\IBVSfigKey{5547-f4.eps}{MQ Peg}{light curve}

\IBVSfig{50mm}{5547-f5.eps}{Light curve for MX~Peg: P = 0.3943902 days,
epoch = 2452872.955 HJD}
\IBVSfigKey{5547-f5.eps}{MX Peg}{light curve}

\IBVSfig{55mm}{5547-f6.eps}{O-C plots for V883~Her, V507~Lyr, and
MQ~Peg (solid lines are non-weighted quadradic fits)}
\IBVSfigKey{5547-f6.eps}{V883 Her, V507 Lyr, MQ Peg}{light curve}


\end{document}
