\documentstyle[twoside,epsf]{article}

\input ibvs2.sty
\input ibvst.sty

\begin{document}

\IBVShead{5052}{30 March 2001}

\IBVStitletl{CCD Light Curves of ROTSE1 Variables, IX:}{ GSC 2530.488 CV\lowercase{n}, GSC 1991.1390 C\lowercase{om}, GSC 1991.1633 C\lowercase{om}}

\IBVSauth{Bl\"attler, E.$^1$; Diethelm, R.$^2$}

\IBVSinst{BBSAG, Schl\"usselacher 1, CH--8636 Wald,
Switzerland; e-mail: blaettler-wald@bluewin.ch}
\IBVSinst{BBSAG, Rennweg 1, CH--4118 Rodersdorf, Switzerland; e-mail: diethelm@astro.unibas.ch}

\SIMBADobj{GSC 2530-488}
\SIMBADobj{GSC 1991-1390}
\SIMBADobj{GSC 1991-1633}

\begintext

{\bf VAR1}\smallskip\hrule

\IBVSTnam{GSC 2530.488 = ROTSE1 J122607.59+355548.9}

\IBVSTcoo{12\hr 26\mm 07\fsec6}{+35\deg 55\arcm 49\arcs}{2000.0}

\IBVSTcomp{GSC 2530.525}

\IBVSTchk{GSC 2530.547}

{\bf VAR2}\smallskip\hrule

\IBVSTnam{GSC 1991.1390 = ROTSE1 J123204.87+262248.1}

\IBVSTcoo{12\hr 32\mm 04\fsec94}{+26\deg 22\arcm 48\farcs6}{2000.0}

\IBVSTcomp{GSC 1991.1415}

\IBVSTchk{GSC 1991.1422}

{\bf VAR3}\smallskip\hrule

\IBVSTnam{GSC 1991.1633 = ROTSE1 J123305.53+270803.4}

\IBVSTcoo{12\hr 33\mm 05\fsec5}{+27\deg 08\arcm 03\arcs}{2000.0}

\IBVSTcomp{GSC 1991.1669}

\IBVSTchk{GSC 1991.1840}

\IBVSfig{10.5cm}{5052-f1.eps}{CCD light curve (without filter) of GSC 2530.488}

\IBVSfig{10.5cm}{5052-f2.eps}{CCD light curve (without filter) of GSC 1991.1390}

% Error corrected Tue Aug 10 14:30:36 MEST 2004 - GSC No. is NOT 1911.1633 !
\IBVSfig{10.5cm}{5052-f3.eps}{CCD light curve (without filter) of GSC 1991.1633}

\hrule

\IBVSTobs{Private observatory, Schl\"usselacher, Wald, 0.15-m refractor}

\IBVSTdet{SBIG ST-7 CCD camera}

\IBVSTfil{None}

\IBVSTdata{Upon request from diethelm@astro.unibas.ch} %email

\IBVSTtyp{ EW }

\newpage

\IBVSTrem{
As a byproduct of the ROTSE1 CCD survey, a large number of new
variables have been discovered (Akerlof et al., 2000). In a series of
papers, we report unfiltered CCD observations for some of the close
binary systems (type EW) in the list of Akerlof et al.\ (2000).  GSC
2530.488 (VAR1 in this paper) was observed with our CCD equipment as
mentioned above during 5 nights between JD 2451951 and JD 2451984,
while the data on GSC 1991.1390 (here VAR2) and GSC 1991.1633 (VAR3)
were collected during the same 5 nights. A total of 171 CCD frames were
measured for VAR1, 162 frames for VAR2 and 160 frames for VAR3.
Figures~1,~2 and~3 show our observations folded with the elements
\begin{center}
\begin{tabular}{ll}
GSC 2530.488 & JD(min,hel)${} = 2451967.325(2) + 0.365714(30) \times E$;\\
GSC 1991.1390 & JD(min,hel)${} = 2451967.3479(9) + 0.2863601(9) \times E$;\\
GSC 1991.1633 & JD(min,hel)${} = 2451967.4962(9) + 0.3379351(17) \times E$.\\
\end{tabular}
\end{center}
These elements of variation are deduced from a linear fit to the newly
determined normal minima from the ROTSE1 data (VAR1: HJD
2451244.6766(15), primary, HJD 2451246.6826(16), secondary; VAR2: HJD
2451312.7287(3), primary; VAR3: HJD 2451246.6822(14), primary,
HJD 2451260.7032(8), secondary) as well as the minima derived from our
data and given in Bl\"attler (2001).\\
The elements of variation for GSC 2530.488 given above should be
checked since the number of revolutions between the ROTSE1 data and
ours is somewhat ambiguous. GSC 1991.1390 and GSC 1991.1633 are
situated within the Coma Cluster (Melotte 111, AV 2059 and AV 2139
respectively).}

\IBVSTack{This research made use of the SIMBAD data base, operated
at CDS, Strasbourg, France.}


\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

Bl\"attler, E., 2001, {\it BBSAG Bulletin}, {\bf 125}, in preparation

\end{document}
