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

\IBVShead{5371}{31 January 2003}

\IBVStitle{CCD Minima for Selected Eclipsing Binaries in 2002}

\IBVSauth{Nelson, Robert H.}

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


\begintext

\vspace*{-1cm}
\IBVSEobs{Sylvester Robotic Observatory\footnote{Formerly 'Backyard Observatory' (BYO)} (SRO):  33 cm f/4.5 Newtonian on Paramount GT-1100s mount.}

\IBVSEdet{SBIG ST7e, 1\farcs24 pixels, 15\farcm8 $\times$ 10\farcm5 FOV, 
cooled to \\& $-$10\deg C $<\ T\ <$ $-$30 \deg C}

\IBVSEred{Aperture photometry using MIRA, by Axiom Research}

\IBVSEmethod{Digital tracing paper method, bisection of chords, curve fitting, 
and (occasionally) Kwee and van Woerden (1956).  See Nelson (2000) for 
more information.}

\vspace*{-0.75cm}
{\small
\begin{table}[!hb]
\begin{center}
\begin{tabular}{|ccccccc|}
\hline
\multicolumn{2}{|l}{\bf Observed star(s):}  & & & & & \\
\hline
Star & GCVS & \multicolumn{2}{c}{J2000} & Comp.  & Epoch $-$ & Latest\\
Name & type & RA$^*$ & Dec & Star & 2400000 & Period (d)\\
\hline
RT And & EA/DW/RS & 23.1110 & 53.0133 & GSC 3998:2212 & 52566.7024 & 0.6289283\\
WZ And & EB/KE: & 1.0143 & 38.0550 & GSC 2799:1170 & 52513.7977 & 0.6956630 \\
AB And & EW/KW & 23.1132 & 36.5335 & GSC 2763:0735 & 52559.6322 & 0.3318910 \\
AD And & EB/DW: & 23.3645 & 48.4016 & GSC 3641:0023 & 52633.6243 & 0.9862163 \\
BX And & EW/DW: & 2.0903 & 40.4739 & GSC 2833:0089 & 52604.6742 & 0.6101144 \\
LO And & EW/KW & 23.2706 & 45.3331 & GSC 3637:0299 & 52524.7879 & 0.3808220 \\
EP And & EW/KW & 1.4229 & 44.4542 & GSC 2827:0575 & 52601.6481 & 0.4041105 \\
ZZ Aur & EB/KE & 5.4542 & 41.0859 & GSC 2915:0220 & 52633.7473 & 0.6012168 \\
BF Aur & EB & 5.0503 & 41.1719 & GSC 2899:0175 & 52600.6934 & 1.5832226 \\
HL Aur & EB/SD & 6.1913 & 49.4207 & GSC 3383:0823 & 52600.8134 & 0.6225055 \\
KU Aur & EA/SD: & 6.2756 & 30.2323 & GSC 2422:0809 & 52618.8453 & 1.3195725 \\
WW Cam & EA/DM & 4.3125 & 64.2145 & GSC 4073:0510 & 52528.907 & 2.2743633 \\
AO Cam & EW/KW & 4.2813 & 53.0245 & GSC 3732:1016 & 52631.7377 & 0.3299284 \\
BU Cas & EA/DM & 1.2841 & 61.0755 & GSC 4031:1639 & 52619.5771 & 2.2551969 \\
GT Cas & EA/SD & 0.1330 & 58.1659 & GSC 3665:0996 & 52524.6942 & 2.9897984 \\
MM Cas & EA/SD & 0.5435 & 54.2636 & GSC 3672:0189 & 52639.5873 & 1.1584800 \\
MN Cas & EA/DM & 1.4203 & 54.5736 & GSC 3675:1855 & 52493.8614 & 1.9169249 \\
OX Cas & EA/DM & 1.0900 & 61.2814 & GSC 4030:0987 & 52608.5841 & 2.4893439 \\
V357 Cas & EB & 23.2951 & 54.5800 & GSC 4033:1848 & 52563.7916 & 0.7607589 \\
V366 Cas & EW/DW & 1.0826 & 58.4417 & GSC 3681:0642 & 52537.8238 & 0.7292900 \\
V459 Cas & EA/DM & 1.1130 & 61.0848 & GSC 4030:0348 & 52565.6717 & 8.4582654 \\
\hline
\end{tabular}
\end{center}
\end{table}
}


\clearpage

{\small
\begin{table}[!ht]
\begin{center}
\begin{tabular}{|ccccccc|}
\hline
\multicolumn{2}{|l}{\bf Observed star(s):}  & & & & & \\
\hline
Star & GCVS & \multicolumn{2}{c}{J2000} & Comp.  & Epoch $-$ & Latest\\
Name & type & RA$^*$ & Dec & Star & 2400000 & Period (d)\\
\hline
BE Cep & EW/KW & 22.4121 & 58.3636 & GSC 3996:0441 & 52490.8752 & 0.4243941 \\
EF Cep & EW & 4.4540 & 80.4426 & GSC 4523:0854 & 52535.812 & 0.6061075 \\
OT Cep & EA & 0.2922 & 82.1005 & GSC 4504:0663 & 52557.7838 & 0.4812310 \\
SS Cet & EA/SD & 2.4836 & 1.4827 & GSC 0047:0638 & 52565.8290 & 2.9739807 \\
XZ CMi & EA & 7.5407 & 3.3854 & GSC 0185:1509 & 52605.9685 & 0.5788091 \\
V387 Cyg & EW/K:  & 21.1537 & 37.2952 & GSC 2714:0043 & 52517.7527 & 0.6405973 \\
V628 Cyg & EW & 21.3404 & 47.1422 & GSC 3595:1315 & 52538.7802 & 0.6516518 \\
V700 Cyg & EW/KW & 20.3113 & 38.4741 & GSC 3153:0819 & 52609.5920 & 0.3400219 \\
V1073 Cyg & EW/KE & 21.2500 & 33.4115 & GSC 2711:2412 & 52569.6317 & 0.7858582 \\
YY Eri & EW/KW & 4.1209 & -10.2810 & GSC 5315:0565 & 52550.9432 & 0.3214990 \\
RW Gem & EA/SD: & 6.0128 & 23.0828 & GSC 1864:1888 & 52619.8506 & 2.8654963 \\
EY Gem & EB/KE & 6.4532 & 17.1331 & GSC 1334:0226 & 52626.7388 & 0.9411168 \\
GW Gem & EB/SD & 7.5229 & 27.0916 & GSC 1933:0570 & 52585.8672 & 0.6594456 \\
DF Hya & EW/KW & 8.5502 & 6.0537 & GSC 0225:0943 & 52600.9568 & 0.3306063 \\
SW Lac & EW/KW & 22.5342 & 37.5619 & GSC 3215:1406 & 52607.5828 & 0.3207186 \\
VX Lac & EA/SD & 22.4101 & 38.1920 & GSC 3214:1036 & 52489.8547 & 1.0745058 \\
VY Lac & EB/KE & 22.4959 & 45.0016 & GSC 3227:0195 & 52482.8311 & 1.0362311 \\
CM Lac & EA/DM & 22.0005 & 44.3308 & GSC 3197:1602 & 52537.6998 & 1.6046917 \\
EM Lac & EW/KW & 22.2355 & 54.0108 & GSC 3982:1914 & 52551.6860 & 0.3891346 \\
SW Lyn & EA/DW & 8.0742 & 41.4802 & GSC 2976:1660 & 52607.8091 & 0.6440658 \\
FR Ori & EB/SD: & 5.5104 & 9.2633 & GSC 0718:0690 & 52635.7590 & 0.8831629 \\
BX Peg & EW/KW & 21.3853 & 26.4223 & GSC 2197:1871 & 52546.6670 & 0.2804186 \\
CC Peg & E & 21.3942 & 28.2455 & GSC 2201:0061 & 52534.7137 & 0.6056033 \\
RT Per & EA/SD & 3.2340 & 46.3436 & GSC 3312:1534 & 52554.7167 & 0.8494059 \\
RV Per & EA/SD & 4.1038 & 34.1555 & GSC 2366:1876 & 52547.8658 & 1.9734905 \\
WY Per & EA/SD & 3.3825 & 42.4041 & GSC 2870:1440 & 52546.8189 & 3.3270740 \\
XZ Per & EA/SD & 4.0928 & 46.3358 & GSC 3328:1131 & 52555.8134 & 1.1516284 \\
V432 Per & EW/KW & 3.1011 & 42.5210 & GSC 2855:0585 & 52516.9010 & 0.3833116 \\
V449 Per & EA/KE & 2.5733 & 35.1401 & GSC 2334:0150 & 52517.9391 & 0.9462100 \\
V579 Per & EW? & 3.3912 & 41.1658 & GSC 2870:2649 & 52559.7957 & 0.4656232 \\
UV Psc & EA/D:/RS & 1.1655 & 6.4842 & GSC 0026:0669 & 52607.6729 & 0.8610407 \\
RZ Tau & EW/KW & 4.3638 & 18.4518 & GSC 1270:0877 & 52551.941 & 0.4156706 \\
CU Tau & EW/KW & 3.4737 & 25.2313 & GSC 1804:2270 & 52551.8458 & 0.4122054 \\
EQ Tau & EW/KW & 3.4813 & 22.1922 & GSC 1260:0575 & 52608.6852 & 0.3413479 \\
V781 Tau & EW/KW & 5.5013 & 26.5743 & GSC 1870:0514 & 52554.9210 & 0.3449080 \\
V Tri & EB/SD & 1.3147 & 30.2202 & GSC 2293:1331 & 52528.7718 & 0.5852056 \\
RV Tri & EA/SD & 2.1318 & 37.0101 & GSC 2321:1715 & 52548.734 & 0.7536616 \\
XY UMa & EB/DW/RS & 9.0956 & 54.2917 & GSC 3805:0479 & 52559.9583 & 0.4789863 \\
\hline
\end{tabular}
\end{center}
$^*$ RA values are in the format HH.MMSS, Dec in DD.MMSS.  'G' stands for 'GSC'.
\vspace*{-0.2cm}
\end{table}
\IBVSEsource{
$O-C$ charts using all available published times of minima.  See 'Bob Nelson's 
$O-C$ Files' in the references.  The epochs above are the latest and best 
times of minima (which usually coincide with the times newly reported here).
}
\vspace*{-0.5cm}
\IBVSEmin{
RT And & 52566.7024 & 0.0002 & s & V & $-$ & \\
WZ And & 52513.7977 & 0.0002 & s & clear & $-$ & \\
AB And & 52559.6322 & 0.0002 & s & R & $-$ & \\
AD And & 52633.6243 & 0.0003 & p & clear & $-$ & \\
BX And & 52604.6742 & 0.0001 & p & I & $-$ & \\
LO And & 52524.7879 & 0.0001 & s & clear & $-$ & \\
EP And & 52601.6481 & 0.0001 & s & clear & $-$ & \\
}
}

\clearpage

{\small
\IBVSEmin{
ZZ Aur & 52633.7473 & 0.0001 & p & clear & $-$ & \\
BF Aur & 52600.6934 & 0.0005 & P & clear & $-$ & \\
HL Aur & 52600.8134 & 0.0002 & p & clear & $-$ & \\
HL Aur & 52635.6739 & 0.0001 & p & clear & $-$ & \\
KU Aur & 52618.8453 & 0.0003 & p & clear & $-$ & C-K slope \\
WW Cam & 52528.907 & 0.002 & p & clear & $-$ & \\
AO Cam & 52631.7377 & 0.0001 & p & clear & $-$ & \\
BU Cas & 52619.5771 & 0.0001 & p & clear & $-$ & \\
GT Cas & 52524.6942 & 0.0004 & p & clear & $-$ & \\
MM Cas & 52639.5873 & 0.0002 & p & clear & $-$ & \\
MN Cas & 52493.8614 & 0.0003 & p & clear & $-$ & \\
OX Cas & 52608.5841 & 0.0004 & p & clear & $-$ & \\
V357 Cas & 52563.7916 & 0.0004 & s & clear & $-$ & \\
V366 Cas & 52537.8238 & 0.0003 & s & clear & $-$ & \\
V459 Cas & 52565.6717 & 0.00005 & p & clear & $-$ & \\
BE Cep & 52490.8752 & 0.00005 & s & clear & $-$ & \\
EF Cep & 52535.812 & 0.001 & s & clear & $-$ & \\
OT Cep & 52557.7838 & 0.0002 & p & clear & $-$ & \\
SS Cet & 52565.8290 & 0.0003 & p & clear & $-$ & \\
XZ CMi & 52605.9685 & 0.0001 & p & clear & $-$ & \\
V387 Cyg & 52517.7527 & 0.0001 & p & clear & $-$ & \\
V628 Cyg & 52538.7802 & 0.0001 & p & clear & $-$ & \\
V700 Cyg & 52609.5920 & 0.0003 & p & clear & $-$ & \\
V1073 Cyg & 52569.6317 & 0.0002 & p & V & $-$ & \\
YY Eri & 52550.9432 & 0.0001 & s & V & $-$ & \\
YY Eri & 52619.7447 & 0.0002 & s & V & $-$ & \\
RW Gem & 52619.8506 & 0.0001 & p & clear & $-$ & \\
EY Gem & 52626.7397 & 0.0003 & p & clear & $-$ & C-K slope \\
GW Gem & 52585.8672 & 0.0003 & p & clear & $-$ & \\
DF Hya & 52600.9568 & 0.0002 & s? & clear & $-$ & \\
SW Lac & 52607.5828 & 0.0001 & p & I & $-$ & \\
VX Lac & 52489.8547 & 0.00003 & p & clear & $-$ & \\
VY Lac & 52482.8311 & 0.0002 & p & clear & $-$ & C-K slope \\
CM Lac & 52537.6998 & 0.0001 & p & V & $-$ & \\
EM Lac & 52551.6860 & 0.0001 & p & clear & $-$ & \\
SW Lyn & 52607.8091 & 0.0001 & p & V & $-$ & \\
FR Ori & 52635.7585 & 0.0005 & p & clear & $-$ & C-K slope \\
BX Peg & 52546.6670 & 0.00005 & s & clear & $-$ & \\
CC Peg & 52534.7137 & 0.0003 & s & clear & $-$ & \\
RT Per & 52554.7167 & 0.0001 & p & clear & $-$ & \\
RV Per & 52547.8658 & 0.0005 & p & clear & $-$ & \\
WY Per & 52546.8189 & 0.00008 & p & clear & $-$ & \\
XZ Per & 52555.8134 & 0.00005 & p & clear & $-$ & \\
V432 Per & 52516.9010 & 0.00004 & p & clear & $-$ & \\
V432 Per & 52550.8236 & 0.0004 & s & clear & $-$ & \\
V449 Per & 52517.9391 & 0.0004 & p & clear & $-$ & \\
V579 Per & 52559.7957 & 0.0005 & p & V & $-$ & \\
UV Psc & 52607.6729 & 0.0001 & p & clear & $-$ & \\
RZ Tau & 52551.941 & 0.001 & p & clear & $-$ & \\
CU Tau & 52551.8458 & 0.0001 & p & clear & $-$ & \\
EQ Tau & 52608.6852 & 0.0002 & p & clear & $-$ & \\
V781 Tau & 52554.9210 & 0.0003 & p & V & $-$ & \\
V Tri & 52528.7718 & 0.0002 & s & clear & $-$ & \\
V Tri & 52547.792 & 0.001 & p & clear & $-$ & \\
V Tri & 52554.8155 & 0.0001 & p & clear & $-$ & \\
RV Tri & 52548.734 & 0.001 & p & clear & $-$ & \\
XY UMa & 52559.9583 & 0.0001 & p & clear & $-$ & \\
}
}

\IBVSEremexp{'C-K slope' refers to a change in the C-K plot of 0.01 magnitudes 
or greater over the observing run.  See below.}

\IBVSErem{
$\quad$In the case of bright stars, V, R or I filters were used to maintain the 
same exposures (of 1-5 minutes) which were required for low random errors.\\
Check stars (K1, K2, ...) were used for all program stars in addition to 
the comparison (C).  However, for some, the plot of comparison-check 
(C-K) magnitude difference versus time revealed a disturbing change of 
0.01 - 0.02 magnitudes over a time span of 0.05 - 0.08 days.\\
$\quad$Further analysis of one of the stars, FR Ori, revealed that check 
stars having nearly equal airmasses gave a check2-check1 (i.e, K2-K1) 
plot versus time constant to within 0.004 (2) magnitudes whereas a third 
check star (K3) having a line of centres with K1 perpendicular to the 
horizon gave K3-K1 changes of 0.023 (3) magnitudes.  Since the C-V 
(variable) line was also perpendicular to the horizon, a tentative 
correction was applied to the light curve resulting in a disturbing 
0.00055 day shift in the time of minimum.  This calls into question 
the accuracy with which some times of minima are reported, here and 
elsewhere.  (For now, no corrections are included in any of the times 
reported here.)\\
$\quad$Further discussion and analysis will be presented in a future IBVS note.
}

\IBVSEack{
$\quad$Thanks are due to Environment Canada for the website satellite images 
(see below) that were essential in predicting clear times for observing 
runs in this cloudy locale.  Thanks are also due to Attilla Danko for 
his Clear Sky Clocks, (see below).\\
Much use was made of the Eclipsing Binary Ephemeris Generator; thanks 
Shawn.\\
$\quad$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

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

Dvorak, S., {\it Eclipsing Binary Ephemeris Generator}, \\
{\tt http://rollinghillsobs.dyn.dhs.org:8000/cgi-bin/calcEBephem.pl}

Kwee, K. K., \& van Woerden, H., 1956, {\it B.A.N.}, {\bf 12}, 327

Nelson, R. H., {\it Bob Nelson's $O-C$ files}, {\tt http://binaries.boulder.swri.edu/binaries/omc/}

Nelson, R. H., 2000, {\it IBVS}, 4840

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

\endreferences

\vspace*{0.5cm}
\IBVSerratum{5040}
~\\
In IBVS 5040, the time of minimum for the GW Cep on 2002-03-19 (UT) should read 51622.8521.
~\\

\end{document}
