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\begin{document}

\IBVShead{5040}{9 March 2001}

\IBVStitle{CCD Minima of Selected Eclipsing Binaries in 2000}

\IBVSauth{Nelson, Robert H.}

\IBVSinsto{College of New Caledonia, 3330 -- 22nd Avenue, Prince
George, BC, Canada, V2N 1P8, \\ \indent e-mail: nelson@cnc.bc.ca}

\IBVSabs{This report presents minima timings of selected eclipsing binaries}

\IBVStyp{ Eclipsing binary }

\begintext

Sixty new times of minima for various eclipsing binaries have been
determined using an unfiltered CCD camera at the Prince George
Astronomical Observatory in 2000.

The CCD camera, a SBIG ST6, was mounted at the cassegrain focus of the
61-cm telescope and cooled to $-40\deg$~C\@. The camera used a telecompressor
lens and operated at $f/7$. Images were taken continuously using the
data acquisition software CCDSoft on ``focus'' mode. Depending on
exposure time for the star (usually between 10 and 60 seconds),
exposures were taken approximately every minute. The duration of
observing runs varied between one and three hours, and typically
covered 100--200 or more frames. Data reduction was by MIRA\@.  For more
details, see Nelson (2000).

A variety of methods (usually a minimum of three) was used to determine
the time of minimum, depending on the nature of the data set.  The
methods available were: the tracing paper method, bisectors of chords,
curve fitting (quadratic on central part, Fourier fit on the full curve
if appropriate) --- all on a spreadsheet, and Kwee--van Woerden (1956)
--- by separate software.  For each time of minimum, the standard
deviation of the resulting times (from the various methods) was used as
a starting point in setting the estimated error, given in Table 1,
column 5.

For each star, the available times of minimum in the literature
were gathered and entered in a spreadsheet; the $O-C$ plots therein
were used to predict times of minimum before observing on a given
night and, based on earlier works, to determine the type of
minimum.  The latter is given in column 6 (I = primary, II =
secondary).

The $O-C$ plots frequently hinted at, or sometimes strongly
indicated a period change; this information is presented in
column 7.  The period behaviour for some of these stars has been
well studied; others await new data and analyses. All the $O-C$
plots, in spreadsheet form, may be obtained from the World-Wide
Web at the relevant URL in the references.

Some of the results were less accurate than desirable due to
problems of sharply varying sky transparency during the run and
limitations in the duration of the run due to the onset of clouds
and other factors.

Another problem was the occasional ambiguous identity of the
variable; the GCVS 4 position did not agree with the GSC
catalogue position, or with RealSky images ($100\times{}$compression of
POSS digital scans).  In these cases, the equivalences are given
in the footnotes.

Three light curves at minimum were chosen at random for
display. See Figures 1--3.

\newpage

\begin{center}
\normalsize
Table 1 \\
\vskip 2mm
\begin{tabular}{lllllccc}
\hline
\lower6pt\hbox{UT date}   & \lower6pt\hbox{Star} & Comp. star & Minimum & Estimated  & \lower6pt\hbox{Type} & Period & \lower6pt\hbox{New period} \\[-2pt]
&      & (GSC No.)  & HJD 24\dots & error & & change? & \\
\hline
2000-10-15 & AD And & 3641-0023 & 51832.81735 & 0\fday00007 & I & -- & 0\fday9861911\\
2000-06-02 & BL And & 3635-1961 & 51697.82162 & 0.00009 & I & -- & 0.7223759\\
2000-09-25 & CN And & 2787-1803 & 51812.8787  & 0.0002  & I & yes? & 0.4627898\\
2000-10-11 & DS And & 2816-1250 & 51828.6893  & 0.0001  & I & -- & 1.0105195\\
2000-08-05 & LO And & 3637-0897 & 51761.8118  & 0.0003  & II? & yes? & 0.3808235\\
2000-02-05 & SS Ari* & 1758-0121 & 51579.7217  & 0.0003  & II & -- & 0.4059839\\
2000-09-27 & ZZ Aur & 2915-0468 & 51814.89102 & 0.00006 & I & -- & 0.6012168\\
2000-12-28 & AH Aur & 1887-1240 & 51906.95915 & 0.0006  & II & -- & 0.4942714\\
2000-02-13 & AC Boo & 3474-0834 & 51588.0118  & 0.0006  & I & yes & 0.3524441\\
2000-03-29 & TY Boo & 2568-0991 & 51632.79821 & 0.00005 & I & -- & 0.3171503\\
2000-12-09 & UZ CMi & 0184-1875 & 51887.9262  & 0.0001  & II & -- & 0.7619496\\
2000-09-23 & AZ Cam & 4547-1052 & 51810.8735 & 0.0001 & I & yes? & 1.3192308\\
2000-03-04 & WW Cam & 4673-1078 & 51607.7921  & 0.0006  & I & yes? & 2.2743713\\
2000-08-30 & CW Cas & 4020-1387 & 51786.8746  & 0.0002  & II & yes? & 0.3188638\\
2000-09-16 & V364 Cas & 3270-0612 & 51803.8936 & 0.0004 & I & -- & 1.5430662\\
2000-09-26 & V364 Cas & 3270-0612 & 51813.9229 & 0.0003 & II & -- & 1.5430662\\
2000-07-22 & V523 Cas & 3257-1068 & 51747.8792 & 0.0001 & I & yes & 0.2336930\\
2000-12-07 & V541 Cas* & 4050-0957 & 51885.8766 &0.0001 & II & -- & 0.9098486\\
2000-03-05 & VZ Cep & 4470-1497 & 51608.7237 & 0.0003 & I & yes? & 1.1833637\\
2000-12-11 & WZ Cep & 4486-1402 & 51889.6940 & 0.0001 & I & -- & 0.4174453\\
2000-05-15 & BE Cep & 3996-0441 & 51679.8576 & 0.0002 & II & -- & 0.4243941\\
2000-12-07 & EF Cep & 4523-0854 & 51885.7625 & 0.0004 & I & -- & 0.6061077\\
2000-01-21 & EG Cep & 4585-0165 & 51564.86095 & 0.00008 & I & -- & 0.5446224\\
2000-03-19 & GW Cep A & 4502-0724 & 51622.5520 & 0.0001 & I & -- & 0.3188440\\
2000-03-31 & GW Cep B & 4502-0724 & 51634.80913 & 0.00015 & II & -- & 0.3188440\\
2000-04-25 & OT Cep & 4504-0663 & 51659.80612 & 0.00005 & I & -- & 0.9624610\\
2000-04-14 & RW Com & 1991-1659 & 51648.77918 & 0.00025 & I & -- & 0.2373453\\
2000-05-12 & RZ Com & 1990-3503 & 51676.7736 & 0.0003 & I & -- & 0.3385073\\
2000-07-24 & CV Cyg & 3137-0227 & 51749.8469 & 0.0002 & II & -- & 0.9834109\\
2000-06-15 & DK Cyg & 2712-1841 & 51710.8499 & 0.0003 & I & yes & 0.4706928\\
2000-05-13 & V387 Cyg* & 2714-0538 & 51677.9260 & 0.0004 & I & -- & 0.6405966\\
2000-07-17 & V401 Cyg* & 2654-1313 & 51742.8339 & 0.0002 & I & yes & 05827244\\
2000-09-25 & V463 Cyg* & 2656-4079 & 51812.7731 & 0.0002 & I & -- & 2.1175747\\
2000-06-16 & V513 Cyg & 3170-0502 & 51711.8397 & 0.0002 & I & -- & 1.0561803\\
2000-12-13 & V680 Cyg & 3968-0228 & 51891.8040 & 0.0003 & I & -- & 1.1991437\\
2000-05-20 & RZ Dra & 3916-1962 & 51684.89711 & 0.00025 & I & -- & 0.5508762\\
2000-03-06 & RW Gem & 1864-1948 & 51609.776 & 0.002 & II & -- & 2.8654961\\
2000-04-16 & GW Gem* & 1933-0570 & 51650.77409 & 0.00007 & I & -- & 0.6594445\\
2000-03-19 & SZ Her & 2610-1214 & 51622.96964 & 0.00025 & II & -- & 0.8180968\\
2000-09-22 & CO Lac & 3992-1927 & 51809.9448 & 0.0002 & I & apsidal & 1.5422071\\
2000-05-26 & EM Lac & 3982-3238 & 51690.91843 & 0.00005 & I & -- & 0.3891347\\
2000-09-21 & PP Lac & 3984-1619 & 51808.6546 & 0.0001 & I & -- & 0.4011633\\
2000-03-26 & XZ Leo & 1412-0423 & 51629.807 & 0.002 & I & yes & 0.4877373\\
2000-05-08 & CE Leo* & 1985-1274 & 51672.79847 & 0.00005 & I & -- & 0.3034290\\
2000-06-03 & TZ Lyr & 3107-0618 & 51698.82501 & 0.00005 & I & -- & 0.5288272\\
2000-12-11 & BO Mon* & 4850-0630 & 51889.9281 & 0.0001 & I & yes & 2.2251719\\
2000-12-13 & V496 Mon & 0151-1326 & 51891.8954 & 0.0002 & I & -- & 0.6607624\\
2000-05-26 & V508 Oph* & 1019-1850 & 51690.8308 & 0.0001 & I & -- & 0.3447905\\
2000-12-28 & V343 Ori* & 0725-0502 & 51906.8087 & 0.0003 & I & -- & 0.8091418\\
2000-09-27 & BO Peg* & 1127-1477 & 51814.7788 & 0.0001 & I & yes? & 0.5804273\\
2000-08-05 & BX Peg* & 2197-1946 & 51761.91545 & 0.0001 & I & yes & 0.2804168\\
2000-12-11 & V432 Per* & 2856-0823 & 51889.8058 & 0.0001 & I & yes & 0.3833100\\
2000-04-14 & AU Ser & 1502-1573 & 51648.88903 & 0.00013 & I & yes & 0.3864935\\
\hline
\end{tabular}
\end{center}

\newpage

\begin{center}
\normalsize
Table 1 (continued) \\
\vskip 2mm
\begin{tabular}{lllllccc}
\hline
\lower6pt\hbox{UT date}   & \lower6pt\hbox{Star} & Comp. star & Minimum & Estimated  & \lower6pt\hbox{Type} & Period & \lower6pt\hbox{New period} \\[-2pt]
&      & (GSC No.)  & HJD 24\dots & error & & change? & \\
\hline
2000-02-12 & RZ Tau & 1274-1281 & 51586.7378 & 0\fday0001 & I & -- & 0\fday4156768\\
2000-10-06 & AH Tau & 1804-2485 & 51823.8420 & 0.0001 & I & yes? & 0.3326779\\
2000-09-24 & CT Tau & 1871-0434 & 51811.8973 & 0.0001 & I & yes & 0.6668249\\
2000-10-05 & EQ Tau* & 1260-0575 & 51822.9035 & 0.0001 & I & -- & 0.3413471\\
2000-01-29 & XY UMa & 3805-0990 & 51572.7472 & 0.0002 & I & -- & 0.478996?\\
2000-01-30 & AG Vir & 0871-0330 & 51573.9120 & 0.0001 & II & -- & 0.6426530\\
2000-04-25 &GP Vul & 2151-1825 & 51659.9171 & 0.0002 & I & -- & 1.0324998\\
\hline
\end{tabular}

\begin{tabular}{p{15.5cm}}
{\bf Notes:} \\
SS Ari = GSC 1758-0116; V541 Cas = GSC 4051-1764; V387 Cyg = GSC
2714-0556; V401 Cyg = GSC 2654-2502; V463 Cyg = GSC 3170-0931; GW Gem =
GSC 1933-0692; CE Leo = GSC 1985-1209; BO Mon = GSC 4837-1454; V508 Oph
= GSC 1019-1840; V343 Ori = GSC 0725-1137; BO Peg = GSC 1127-0916; BX
Peg = GSC 2197-1458; V432 Per = GSC 2856-1647; EQ Tau = GSC 1260-0909
\end{tabular}
\end{center}

\IBVS2fig{7.5cm}{5040-f1.eps}{Secondary minimum of the 0\fday76 W UMa-type binary UZ Canis Minoris}{5040-f2.eps}{Primary minimum of the 0\fday30 W UMa-type binary CE Leonis}

\IBVSfig{6.5cm}{5040-f3.eps}{Primary minimum of the 0\fday58 $\beta$
Per-type binary BO Pegasi}

{\it Acknowledgements:} Thanks are due to Mr.~Brian Battersby for
assisting on some of the observing runs.  In addition, the satellite
views from the Environment Canada website (see below) were essential in
predicting clear times for observing runs in this cloudy locale.
Thanks are also due to Arne Henden, Peter Guilbault, Gary Billings,
Chuck Pullen, Dirk Terrell, and David Williams, for useful comments and
corrections. Thanks also the editor and referee Katalin Ol\'ah who caught
some mistakes and suggested some improvements. The author is also a
Guest User of the Canadian Astronomy Data Centre, which is operated by
the Dominion Astrophysical Observatory for the National Research
Council of Canada's Herzberg Institute of Astrophysics.

\references

Kwee, K.K., and Van Woerden, H., 1956, {\it BAN}, {\bf
12}, No.\ 464, 327

Nelson, R.H., 2000, {\it IBVS}, No.\ 4840

{\tt http://www.cmc.ec.gc.ca/cmc/htmls/satellite.html}

{\tt http://www.cnc.bc.ca/physics/EB\_Database.htm}

\endreferences


\vspace*{2.5cm}
%from IBVS 5371
\IBVSerratum{5040}
~\\
In IBVS 5040, the time of minimum for the GW Cep on 2002-03-19 (UT) should read
51622.8521.
~\\

\end{document}
