\documentstyle[twoside, ibvs2, ibvst, epsf]{article}

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\IBVShead{5161}{29 August 2001}

\IBVStitle{V1542 A\lowercase{ql} is an Eclipsing Binary of W UM\lowercase{a} type}

\vskip-8pt \centerline{(BAV MITTEILUNGEN NO. 138)}
\vskip18pt

\IBVSauth{Quester, W.$^{1,3}$; Bernhard, K.$^{2,3}$}

\IBVSinst{D--73730 Esslingen, Germany, e-mail: wquester@aol.com}

\IBVSinst{A--4030 Linz, Austria, e-mail: kl.bernhard@aon.at}

\IBVSinst{Bundesdeutsche Arbeitsge\-mein\-schaft f\"{u}r Ver\"{a}nderliche
Sterne e.V. (BAV), Munsterdamm 90,\\ \indent D--12169~Berlin, Germany}

\SIMBADobj{V1542 Aql}

\begintext

\IBVSTnam{V1542 Aql = GSC 1057.01309 = Brh V8}

\IBVSTcoo{19\hr46\mm25\fsec1}{$+08\deg45\arcm12\arcs$}{2000}

\IBVSTobs{W. Quester: Private observatory, 20-cm Cassegrain telescope $f/6.4$;\\
K. Bernhard: Private observatory, 20-cm Schmidt--Cassegrain telescope}

\IBVSfig{7.75cm}{5161-f1.ps}{Differential $V$ light curve of V1542 Aql
measured in July 2001}

\IBVSTdet{W. Quester: ST-7E camera;\\
& K. Bernhard: Starlight Xpress SX camera}

\IBVSTfil{W. Quester: Bessel $V$;\\ & K. Bernhard: None}

\IBVSTcomp{GSC 1057.01223, $V\approx10\fmm4$}

\IBVSTchk{GSC 1057.01437, GSC 1057.01527}

\IBVSTsysn

\IBVSTdata{Upon request}

\IBVSedata{5161-t1.txt}

\IBVSTtyp{  W UMa  }

\IBVSTrem{
V1542 Aql was discovered by Bernhard (1999) as a variable star.
Bernhard and Lloyd (1999) published possible light curves and results
of a period search. They concluded that the star either is a $\beta$
Cep-, $\delta$ Sct- or a W UMa-type variable with four possible periods
in the range from 0.172675 to 0.417570 days. \\
W. Quester observed V1542 Aql during 4 nights in July 2001. The rms
error of single observations is $\pm 0\fmm02$. The light curve, folded
with the period given below, shows variations of a W UMa-type eclipsing
variable (Figure 1).\\
The following times of minima were observed (HJD 2400000\,+):
\begin{center}
\begin{tabular}{lcl|lcl}
\hline
minimum time & type &  observer  & minimum time    & type &  observer  \\
\hline
51065.388      &  s   &  Bernhard  &  52113.3933(07) &  p   & Quester    \\
51080.405      &  p   &  Bernhard  &  52113.6000(15) &  s   & Quester    \\
51103.378      &  p   &  Bernhard  &  52115.4825(07) &  p   & Quester    \\
51111.3146(10) &  p   &  Bernhard  &  52116.5270(05) &  s   & Quester    \\
52112.5593(10) &  p   &  Quester   &                 &      &            \\
\hline
\end{tabular}
\end{center}
Figures in brackets denote rms errors in units of the last
decimal, p and s denote primary and secondary minima. The
uncertainty of Bernhard's first three minima may be around
$\pm0.01$\, day; these minimum times are based on only a few
observations during each night. They were given lower weight in
the calculation of the period. Resulting elements of the light
variations are:
\belowdisplayskip-12pt
\begin{equation}
\begin{array}{r@{}r@{}l}
{\rm Min~ p = HJD~}2452112.1411 & {} + 0\fday4175361 & {} \times E. \\
 \pm 16 & \pm 13 \\
\end{array}
\end{equation}}

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

\references

Bernhard, K., 1999, {\it vsnet-obs}, No.\ 19782,\\
http://www.kusastro.kyoto-u.ac.jp/vsnet/Mail/obs19000/msg00782.html

Bernhard, K., Lloyd. C., 1999, {\it IBVS}, No.\ 4685

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