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\IBVShead{5067}{8 May 2001}

\IBVStitle{Times of Minima of Eclipsing Binaries}

\IBVSauth{Sandberg Lacy, Claud H.; Hood, Ben; Straughn, Amber}

\IBVSinsto{Department of Physics, University of Arkansas, Fayetteville,
Arkansas 72701, USA}

\begintext

We report times of minima of eclipsing binary stars derived from $V$-band
photometric observations made by an automated observatory at the
University of Arkansas (the URSA telescope). The URSA telescope is a
10-inch aperture Meade LX-200 $f/6.3$ with an SBIG ST8EN CCD camera
(before 2000 September 1, an SBIG ST6 camera was used). Observations
were made through a Bessel $V$ filter. The observations were 60 seconds
integrations followed by 30 seconds as the image was downloaded and
stored on the control computer. Images were dark-subtracted and
flat-fielded before being processed by a virtual measuring engine
(manual measurements were made before 2000 November 14). Differential
magnitudes were measured relative to a comparison star and a check star
in the same $20\arcm \times 30\arcm$ frame. Constancy of the comparison
stars on a time scale of months has been verified by comparisons with a
third comparison star in the field. Pixel size was 1.15 arcsec$^2$. For
each variable star, the ultimate measurement accuracy for differential
magnitude measurements depends on the availability of suitably bright
comparison stars within the same image, which is 30\arcm\ wide E--W and
20\arcm\ wide N--S\@. This ultimate accuracy can range from 0\fmm004 to
0\fmm02 for our program stars. Additionally, we sometimes observe
through thin cirrus. This can double the standard errors. A sample of
the observations is shown in Figure~1. Heliocentric times of minima
were estimated by using the method of Kwee and van Woerden (1956) as
adapted to a Macintosh computer. Uncertainties in the times of minima
were estimated from the values of standard error computed by the
method. In Table~1, primary eclipses are designated as type~1 eclipses,
and secondary eclipses as type~2.

\newpage

\begin{center}
{\normalsize Table 1}
\vskip2mm
\begin{tabular}{ll@{${}\pm{}$}lc}
\hline
\lower6pt\hbox{Star} & \multicolumn2c{\lower6pt\hbox{JD of Min${} - 2400000$}} & Type of \\[-2pt]
& \multicolumn2c{} & Eclipse \\
\hline
KP Aql    &  51751.6264  & 0.0005      & 1 \\
WW Cam    &  51474.7295  & 0.0006      & 2 \\
AY Cam    &  51919.8679  & 0.0005      & 1 \\
          &  51974.5666  & 0.0006      & 1 \\
          &  51989.60769 & 0.00014     & 2 \\
          &  52015.5921  & 0.0005      & 1 \\
IT Cas    &  51826.6876  & 0.0010      & 1 \\
MU Cas    &  51876.5835  & 0.0004      & 1 \\
V459 Cas  &  51863.63570 & 0.00014     & 1 \\
          &  51867.7992  & 0.0005      & 2 \\
          &  51918.5502  & 0.0004      & 2 \\
WW Cep    &  51739.7305  & 0.0014      & 2 \\
          &  51868.55092 & 0.00015     & 2 \\
          &  51914.5600  & 0.0004      & 2 \\
RT CrB    &  51993.8053  & 0.0011      & 2 \\
RW CrB    &  51931.9083  & 0.0003      & 1 \\
          &  51936.9931  & 0.0004      & 1 \\
          &  51982.7572  & 0.0004      & 1 \\
          &  52011.8148  & 0.0004      & 1 \\
          &  52023.8029  & 0.0004      & 2 \\
          &  52024.8899  & 0.0003      & 1 \\
V477 Cyg  &  51720.7450  & 0.0004      & 1 \\
V885 Cyg  &  52025.8414  & 0.0006      & 2 \\
V1061 Cyg &  52015.90554 & 0.00011     & 1 \\
UZ Dra    &  52017.86742 & 0.00012     & 2 \\
DI Her    &  51757.7215  & 0.0013      & 2 \\
RW Lac    &  51750.6943  & 0.0006      & 2 \\
RU Mon    &  51862.9000  & 0.0003      & 1 \\
TY Tau    &  51582.6638  & 0.0007      & 1 \\
          &  51862.7781  & 0.0005      & 1 \\
          &  51868.7074  & 0.0005      & 2 \\
          &  51869.7830  & 0.0004      & 2 \\
          &  51875.7080  & 0.0002      & 1 \\
          &  51876.7850  & 0.0004      & 1 \\
          &  51877.8624  & 0.0003      & 1 \\
          &  51882.7130  & 0.0004      & 2 \\
          &  51883.7900  & 0.0006      & 2 \\
          &  51924.7290  & 0.0010      & 2 \\
          &  51931.7309  & 0.0004      & 1 \\
          &  51943.5824  & 0.0005      & 1 \\
          &  51951.6609  & 0.0007      & 2 \\
          &  51985.6011  & 0.0003      & 1 \\
CF Tau    &  51919.7246  & 0.0005      & 2 \\
          &  51966.5772  & 0.0007      & 2 \\
\hline
\end{tabular}
\end{center}

\newpage

\IBVSfig{10cm}{5067-f1.ps}{A sample observation of a primary eclipse on 2000 November 15
UT\@. Approximately the last half of the observations were made through thin
cirrus clouds. Note that the standard error of the observations was larger
then}


\reference

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

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