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\input ibvs2.sty

\begin{document}
\IBVShead{5228}{24 January 2002}

\IBVStitle{Eclipsing Variable GSC 2084.0777 = ROTSE1 J174103.55+273429.1}

\IBVSauth{Nelson, R.H.$^1$; Lubcke, G.C.$^2$; Henden, A.A.$^3$; Guilbault, P. R.$^4$}

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

\IBVSinst{3817 Patrick Henry Way, Middleton, Wisconsin 53562, USA,
e-mail: gil2@ix.netcom.com}

\IBVSinst{Universities Space Research Association/U.S. Naval
Observatory, P.O.Box 1149, Flagstaff, \\ \indent Arizona
86002-1149, USA, e-mail: aah@nofs.navy.mil}

\IBVSinst{P.O. Box 287, Chepachet, RI 02814, USA, e-mail: pete1199@aol.com}

\IBVSabs{We report on the nature of GSC 2084.0777}

\SIMBADobj{GSC 2084-0777}

\IBVStyp{EW}

\begintext

The wealth of data gathered by the ROTSE1 CCD Survey (Akerlof et
al., 2000) has resulted in the discovery of a large number of
previously unknown variable stars, many of which are eclipsing
binaries. In a continuing cooperative effort, the variability
of GSC 2084.0777 = ROTSE1 J174103.55+273429.1 has been studied by
a team of AAVSO members. All sky photometry was performed in order
to determine the color indices for the variable and comparison
stars. We used CCD and photographic observations to accurately
determine the light elements of the system. In this note we
discuss our methods of observation and present an ephemeris and
light curve.

From his private observatory Lubcke observed the system with a
0.28-m Schmidt- Cassegrain telescope equipped with a ST9E CCD. On
12 nights, from JD2451775 to JD2452120. A total of 362 observations were made, yielding four
primary and two secondary times of minimum. Nelson observed ${\rm GSC}
 2084.0777$ from the observatory of the Prince George Astronomical
Society using a 0.60-m Cassegrain telescope and a ST6 CCD camera.
From these unfiltered observations three times of primary minimum
and four times of secondary minimum were extracted.

Henden used the USNO Flagstaff Station 1.0-m. telescope equipped
with a SITe/Tektro- nix $1024\times1024$ CCD to observe the field in
the standard Johnson-Cousins $BVR_{c}I_{c}$ passbands on five
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. With magnitude and color errors shown in
parenthesis to the last decimal place, the variable, comparison
and check stars were standardized as follows:

{\small
\begin{center}
\begin{tabular}{cccccccc}
\hline
Star & GSC & RA (J2000) & DEC & $V$ & $B-V$ & $V-R_{c}$ & $R_{c}-I_{c}$\\
\hline

var $^1$& 2084.0777 & 17:41:03.354 & +27:34:34.77 & 11.887(2) & 0.617(1) & 0.361(2) & 0.338(2)\\
var $^2$& 2084.0777 & 17:41:03.354 & +27:34:34.77 & 12.374(3) & 0.630(3) & 0.366(4) & 0.350(5)\\
comp & 2084.1119 & 17:41:29.097& +27:37:06.70 & 12.594(2) & 0.476(18) & 0.283(11) & 0.293(12) \\
check & 2084.1154 & 17:41:31.324 & +27:31:39.99 & 12.472(24) & 0.766(15) & 0.410(12) & 0.366(11) \\

\hline
\end{tabular}
\end{center}

\begin{tabular}{l p{13cm}}
1 = maximum light, 2 = primary minimum. \\
\end{tabular}
}

\vskip 0.5cm

More complete photometric information about all stars within 5
arcmin of the variable can be found in 5228-t2.txt. In addition,
Henden recorded a time of primary minimum in $V$ which appears in
Table 1.

\IBVSedata{5228-t2.txt}

Guilbault visited the Harvard College Observatory and estimated
the brightness of GSC 2084.0777 on 165 blue- sensitive
photographic plates from the AC, Damon and RH Patrol Series. From
these observations 24 times of minimum light were gathered. The
times of minimum light from all sources are collected in Table 1.

\begin{center}

{\normalsize Table 1. Times of minimum, GSC 2084.0777} \vskip2mm
\begin{tabular}{r@{.}lccccccc}
\hline
\multicolumn{2}{c}{HJD} & Type & Error &  Cycle & $O-C$ & Phase  &   Observer     &  Source\\
\multicolumn{2}{c}{2400000\,+} && $+/-$ && $(d)$ &&& \\
\hline
25369&845&  I &-          &$-$66420 & $-$0.006& 0.986 & Guilbault    &   pg\\
28012&605&  I  &-          &$-$59777 & $-$0.021 & 0.947  & Guilbault    &   pg\\
28716&761&  I &-          &$-$58007 & $-$0.022 & 0.945 & Guilbault    &   pg\\
29816&642& II &- &  $-$55242 & $+$0.062  & 0.656 & Guilbault    &   pg\\
42219&718& II &-         &$-$24065 & $+$0.035  & 0.587 & Guilbault    &   pg\\
42325&513& II &-          &$-$23780 & $+$0.008  & 0.518 & Guilbault     &   pg\\
42574&753&  I  &-          &$-$23173 & $+$0.008  & 0.019 & Guilbault     &   pg\\
42684&517&  I  &-          &$-$22897 & $-$0.029  & 0.925 & Guilbault    &   pg\\
42844&897&  I  &-          &$-$22494 & $+$0.026  & 0.065 & Guilbault    &   pg\\
44369&735&  I &-          &$-$18658 & $-$0.013 & 0.967 & Guilbault     &   pg\\
44425&642& II &-          &$-$18541 & $-$0.001  & 0.497 & Guilbault    &   pg\\
44465&648&  I  &-          &$-$18420 & $+$0.023  & 0.058 & Guilbault     &   pg\\
44732&762&  II &-          &$-$17749 & $-$0.005 & 0.488 & Guilbault    &   pg\\
44782&680&  I  &-          &$-$17623 & $-$0.014  & 0.964 & Guilbault     &   pg\\
44836&609& II   &-          &$-$17487 & $+$0.009 & 0.523 & Guilbault    &   pg\\
45053&830& II   &-          &$-$16941 & $-$0.016  & 0.523 & Guilbault    &   pg\\
45260&491&   I &-          &$-$16422 & $+$0.005  & 0.011 & Guilbault    &   pg\\
45823&795&  I  &-          &$-$15006 & $+$0.017 & 0.958 & Guilbault     &   pg\\
46146&862& I &-          &$-$14194 & $+$0.013  & 0.034 & Guilbault     &   pg\\
46562&780& II &-          &$-$13149 & $+$0.002  & 0.504 & Guilbault    &   pg\\
46652&684& II &-          &$-$12923 & $-$0.004  & 0.491 & Guilbault    &   pg\\
47243&875& II &-         & $-$11436 & $+$0.014 & 0.535 & Guilbault & pg\\
47294&801& II  &-          &$-$11308 & $+$0.018  & 0.545 & Guilbault    &   pg\\
47628&755&  I  &-          &$-$10469 & $-$0.005  & 0.987 & Guilbault    &   pg\\
51781&6929& I  &0.0001  &$-$30     & $+$0.000  & 0.999 & Lubcke   &   CCD unfiltered\\
51784&6766& II &0.0001  &$-$23     & $+$0.000  & 0.499 & Lubcke   &   CCD unfiltered\\
51792&6334& II &0.0001  &$-$3    & $+$0.000  & 0.499 & Lubcke   &   CCD unfiltered\\
51793&6282&  I &0.0001  &0    & $+$0.000  & 0.000 & Lubcke   &   CCD unfiltered\\
51803&5742&  I &0.0004  &$+$25    & $+$0.000  & 0.001 & Lubcke   &   CCD unfiltered\\
51809&7395& II &0.0006  &$+$40    & $-$0.001  & 0.498 & Nelson   &   CCD unfiltered\\
52000&8971&  I &0.0001  &$+$521   & $-$0.000  & 0.000 & Nelson   &   CCD unfiltered\\
52020&7876&  I &0.0002  &$+$571   & $-$0.001  & 0.998 & Nelson   &   CCD unfiltered\\
52038&8897& II &0.0001  &$+$617   & $+$0.001  & 0.500 & Nelson   &   CCD unfiltered\\
52047&8403&  I &0.0001  &$+$639   & $+$0.000  & 0.999 & Nelson   &   CCD unfiltered\\
52054&8020& II &0.0001  &$+$656   & $+$0.000 & 0.498 & Nelson   &   CCD unfiltered\\
52073&8980& II &0.0003  &$+$704  & $+$0.000 & 0.499 & Nelson & CCD unfiltered\\
52110&6974&    I        &0.0000  &$+$797  &$+$0.000  & 0.999 & Henden  & CCD $V$-filter\\
52120&6434&     I       &0.0001  &$+$822  & $+$0.000  & 0.000 & Lubcke  & CCD $V$-filter\\
\end{tabular}
\end{center}

\vskip 0.5cm

The CCD times of minimum were determined using the computer
program $AVE$ (Barbera, 2000) based on the Kwee--Van Woerden
(1956) method. These photometric times of primary minima were
fitted into a least squares solution to yield the preliminary
light elements HJD$_I$ = 2451793.6282(0) + 0\fday39782832(10)$ \times
 E$. The archival minima gathered at Harvard have enabled us to
more accurately refine the period of GSC 2084.0777. In most cases
the photographic exposures were of 60 minutes duration and the
time of mid-exposure is the date the variable was estimated to be
at minimum light. The earliest primary minima have been excluded from our solution. The Harvard
primary minima from 2442574 to 2447628 were assigned a weight of 1
and the CCD primary minima a weight of 10. Our analysis determined
the following ephemeris:

$$ \begin{array}{r@{}r@{}l} {\rm Min.~I = HJD~} 2451793.6280 & {}
+ 0\fday39782863 & {} \times E.\\
\pm 0.0006 & {} \pm 0.00000010\\
\end{array} $$


The unfiltered CCD observations by Lubcke were folded using the
elements above and the phased light curve is shown in Figure 1,
and these data are available electronically as 5228-t3.txt
through the $IBVS$ Web site. The magnitudes shown are differential
magnitudes with respect to the comparison star GSC 2084.1119.

\IBVSedata{5228-t3.txt}

\vskip 1.0cm

\IBVSfig{10cm}{5228-f1.eps}{Differential phased light curve, GSC
2084.0777- unfiltered CCD - Lubcke.}

The CCD light curve shows that the star is a W Ursae Majoris type
(EW) eclipsing variable that is characterized by continuous light
changes, with the primary and secondary minima being almost equal
in depth.

The phase diagram of the folded Harvard photographic data is shown
in Figure 2. These observations are available as 5228-t4.txt.
Estimates were made by eye, and a sequence of steps was used to
determine changes in brightness with respect to comparison stars
GSC2084.0693 and GSC2084.1154.

\IBVSedata{5228-t4.txt}
\vskip 1.0cm

\IBVSfig{10cm}{5228-f2.eps}{Phased Harvard light curve, GSC
2084.0777.}

We wish to thank Alison Doane, acting Curator of the Astronomical
Photograph Collection at the Harvard College Observatory, for use
of the Harvard Patrol Plates. We also would like to thank Dr. Dirk
Terrell of the Southwest Research Institute located in Boulder,
Colorado USA, for his helpful suggestions, and Timothy Hager for
drawing the light curves used in this report.

\IBVSefigure{5228-f3.ps}
%\IBVSefigureKey{5228-f3.ps}{GSC 2084.0777}{finding chart}
\IBVSecomment{Finder Chart for GSC 2084-0777}

\references

Akerlof, C., Amrose, S., Balsano, R., Bloch, J., Casperson, D.,
Fletcher, S., Gisler, G., Hills, J., Kehoe, R., Lee, B., Marshall,
S., McKay, T., Pawl, A., Schaefer, J., Szymanski, J., Wren, J.,
2000, {\it AJ}, {\bf 119}, 1901

Barbera, R., 2000, {\tt http://www.gea.cesca.es}

Henden, \,A.\,2000,\,{\tt
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/sequence/g2084.dat}

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

\end{document}

