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\begin{document}

\IBVShead{5539}{24 June 2004}

\IBVStitle{Four RR Lyrae Stars with Variable Periods in Ophiuchus}

\IBVSauth{H\"{a}ussler, K.$^1$; Berthold, T.$^{1, 2}$; Kroll, P.$^2$}

\IBVSinst{Bruno-H.-B\"{u}rgel-Sternwarte, T\"{o}pelstr. 46, D-04746 Hartha, Germany}

\IBVSinst{Sternwarte Sonneberg, Sternwartestr. 32, D-96515 Sonneberg, Germany}

\indent {
\small{email: sternwartehartha@lycos.de, tb@stw.tu-ilmenau.de, pk@stw.tu-ilmenau.de}}

\SIMBADobj{V1077 Oph}
\SIMBADobj{V1090 Oph}
\SIMBADobj{V1097 Oph}
\SIMBADobj{V2029 Oph}

\begintext
\vspace*{-0.8cm}

Hoffmeister (1967) has reported the discovery of the RR Lyr stars analysed in the present paper.
No ephemerides were published for V1097 Oph and V2029 Oph until today and,
in the other cases, period variations were detected as a result of our observations.
Photographic plates of a field centered around 67 Oph,
taken with the Sonneberg Observatory 40cm Astrograph during three intervals spread
over the years from 1938$-$1994,
were used to check the behaviour of these objects (see \mbox{Table 1}).
The elements listed below were obtained by means of least-squares solutions.
Already published times of maxima for V1077 Oph and V1090 Oph (Ivanij and Samus, 1994,
and Konoplyov, 1986) were included in these solutions.

Photographic amplitudes were derived with respect to magnitudes of the
comparison stars given in Table 2. Individual data are available upon request.

\vskip 4mm
\parindent0mm
{\em Remarks:}
\vskip 1mm
{\em V1077 Oph}

A first and somewhat preliminary set of elements consisting of 3 slightly different periods
derived from observations covering only about 2000 days was published by Konoplyov (1986).
The light curves in this paper show considerable scatter especially between phases 0.3 and 0.8.
The observations reported here allow to confirm in principle the value of the period and
have ascertained a major period change occurred around J.D. 2441500.
Elements listed in Table 1 are valid for J.D. 2429100$-$2439600 and J.D. 2442900$-$2449500, resp.

\vskip 1mm
{\em V1090 Oph}

Although a precise time of the period change can not be clearly deduced from
the (O$-$C)-diagram, the composite light curve drawn with these period values
gives some hints to assume a period change took place around J.D. 2438500.
Elements are at least valid for J.D. 2429100$-$2431700 and J.D. 2438200$-$2449500, resp.

\vskip 1mm
{\em V1097 Oph}

A similar situation applies to V1097 Oph.
Our elements given below are at least valid for the intervals of JD 2429100$-$2431700
and J.D. 2438200$-$2449500.
Unfortunately there were no plates available in between these times. So, the 
(O--C)-diagram
represents only one reasonable version of the stars period history.

\vfill\eject
{\em V2029 Oph}

Only observations from J.D. 2438258$-$2449488 were displayed in the light curve because of
the uncertainties concerning the set of elements valid prior to this date.
The given ephemeris is valid for J.D. 2438900$-$2449200.


\begin{table}[!ht]
\normalsize
\centerline{Table 1. Summary of this paper}
\vskip 3mm
\begin{center}
\begin{tabular}{lcrrcrrcc}
\hline
Star          & Type  &   Epoch      &Period         &  Max.   & Min.     & M$-$m    & No. of \\
              &       &  2400000+    & (day)         &         &          &          & Plates   \\
\hline
V1077 Oph (1) & RRab  &39259.556     & 0.3739892     & 15\fmm2 & 15\fmm9  & 0\fper18 &58 \\
              &       &  $\pm$15     &    $\pm$8     &         &          &          &\\
V1077 Oph (2) &       &48100.422     & 0.3739738     &         &          &          &67 \\
              &       &   $\pm$6     &    $\pm$6     &         &          &          &\\
V1090 Oph (1) & RRab  &38528.505     & 0.5266866     & 14\fmm9 &$>$15\fmm6& 0\fper15 &41 \\
              &       &  $\pm$12     &   $\pm$10     &         &          &          &\\
V1090 Oph (2) &       &43933.604     & 0.5266592     &         &          &          &74 \\
              &       &   $\pm$4     &   $\pm$10     &         &          &          &\\
V1097 Oph (1) & RRab  &29790.437     & 0.5927486     & 14\fmm8 & 16\fmm4  & 0\fper20 &132 \\
              &       &   $\pm$8     &    $\pm$3     &         &          &          &\\
V1097 Oph (2) &       &47770.340     & 0.5927533     &         &          &          &42 \\
              &       &   $\pm$6     &    $\pm$8     &         &          &          &\\
V2029 Oph     & RRab  &49154.467     & 0.5900729     & 14\fmm9 & 15\fmm5  & 0\fper13 &114 \\
              &       &  $\pm$12     &   $\pm$11     &         &          &          &\\

\hline

\end{tabular}
\end{center}
\end{table}

\vskip 3mm

\begin{table}[!hb]
\centerline{Table 2. Comparison stars and cross references}
\vskip 3mm
\begin{center}
\begin{tabular}{ccrcr}
\hline
    &  V1077 Oph           &     &  V1090 Oph          &\\
    &  S 9843           &     &  S 9863          & \\
    &  USNO 0900-10764128 &     &  USNO 0975-10473162& \\
\hline
Comp. No.  &  USNO      & m$^*$     & USNO      & m$^*$\\
\hline
1   &  0900-10762796 &  15\fmm3  & 0975-10468047 & 14\fmm7\\
2   &  0900-10758477 &  15\fmm6  & 0975-10481309 & 15\fmm0\\
3   &  0900-10756678 &  15\fmm8  & 0975-10473364 & 15\fmm2\\
4   &  0900-10759166 &  16\fmm1  & 0975-10476690 & 15\fmm7\\
\hline
&&&&\\
&&&&\\
\hline
    & V1097 Oph           & & V2029 Oph &\\
    & S 9874             & & S 9846    &\\
    & USNO 0900-12237409 & & USNO 0900-10886697 & \\
\hline
Comp. No.  &  USNO     & m$^*$     & USNO     & m$^*$\\
\hline
1   & 0900-12236119 & 14\fmm5&  0900-10893744 &  14\fmm6\\
2   & 0900-12237108 & 15\fmm2&  0900-10891766 &  15\fmm0\\
3   & 0900-12241628 & 15\fmm7&  0900-10892260 &  15\fmm3\\
4   & 0900-12240377 & 16\fmm4&                &         \\
\hline

\end{tabular}
\end{center}
\centerline{\normalsize $^*$ Magnitudes refer to the B values of the USNO$-$A2.0 catalogue}
\end{table}


\vskip 4mm

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


\IBVS2fig{7cm}{5539-f1.eps}{Composite light curve of V1077 Oph}{5539-f2.eps}{(O$-$C) diagram for V1077 Oph\vspace*{-5cm}}
\IBVSfigKey{5539-f1.eps}{V1077 Oph}{light curve}
\IBVSfigKey{5539-f2.eps}{V1077 Oph}{O-C diagram}



\IBVS2fig{7cm}{5539-f3.eps}{Composite light curve of V1090 Oph}{5539-f4.eps}{(O$-$C) diagram for V1090 Oph}
\IBVSfigKey{5539-f3.eps}{V1090 Oph}{light curve}
\IBVSfigKey{5539-f4.eps}{V1090 Oph}{O-C diagram}

\IBVS2fig{7cm}{5539-f5.eps}{Composite light curve of V1097 Oph}{5539-f6.eps}{(O$-$C) diagram for V1097 Oph}
\IBVSfigKey{5539-f5.eps}{V1097 Oph}{light curve}
\IBVSfigKey{5539-f6.eps}{V1097 Oph}{O-C diagram}


\IBVS2fig{7cm}{5539-f7.eps}{Light curve \mbox{(J.D. 2438258 $-$ 2449488)} of V2029 Oph }{5539-f8.eps}{(O$-$C) diagram for V2029 Oph}
\IBVSfigKey{5539-f7.eps}{V2029 Oph}{light curve}
\IBVSfigKey{5539-f8.eps}{V2029 Oph}{O-C diagram}


%\IBVS2fig{7cm}{5539-f7.eps}{Light curve \mbox{(J.D. 2438258 $-$ 2449488)} of V2029 Oph }{5539-f8.eps}{(O$-$C) diagram for V2029 Oph\vspace*{-8cm}}


\clearpage

\begin{table}[!ht]
\centerline{\normalsize Table 3. Heliocentric times of new found maxima and $O-C$ values according}
\centerline{\normalsize to the elements derived in this paper}
%\small
\vskip 3mm
\begin{center}
\begin{tabular}{llrrllrr}
\hline
Star   &  JD (max.$^*$) &Epoch &$O-C$  &  Star   &  JD (max.$^*$) &Epoch &$O-C$  \\
\hline
V1077 Oph (1)&29786.410&$-$25330&0.001&V1097 Oph (1)&38549.486&14777&0.002\\
&29844.389&$-$25175&0.012&&40383.442&17871&$-$0.006\\
&38258.415&$-$2677&0.028&&41150.468&19165&0.003\\
&39259.546&0&$-$0.010&V1097 Oph (2)&45087.530&$-$4526&$-$0.011\\
V1077 Oph (2)&43303.469&$-$12827&0.008&&45486.458&$-$3853&$-$0.004\\
&45916.405&$-$5840&$-$0.011&&46272.443&$-$2527&$-$0.006\\
&47744.399&$-$952&0.000&&46554.584&$-$2051&$-$0.014\\
&48100.423&0&0.001&&46731.243&$-$1753&0.005\\
&48830.441&1952&0.022&&47368.480&$-$678&0.035\\
&49475.511&3677&$-$0.013&&47387.432&$-$646&0.019\\
V1090 Oph (1)&29785.522&$-$16600&0.016&&47770.344&0&0.015\\
&29786.540&$-$16598&$-$0.020&V2029 Oph&29843.418&$-$32727&0.269\\
&29843.446&$-$16490&0.004&&38902.505&$-$17374&$-$0.034\\
&38528.528&0&0.023&&39259.546&$-$16769&0.013\\
&38557.449&55&$-$0.023&&39671.440&$-$16071&0.036\\
&39259.546&1388&0.000&&39681.476&$-$16054&0.040\\
V1090 Oph (2)&45087.521&2191&0.006&&39684.350&$-$16049&$-$0.036\\
&45115.469&2244&0.041&&40382.440&$-$14866&$-$0.002\\
&45530.427&3032&$-$0.008&&45492.490&$-$6206&0.016\\
&46272.507&4441&0.009&&46476.693&$-$4538&$-$0.023\\
&46289.368&4473&0.017&&46554.584&$-$4406&$-$0.021\\
&46290.421&4475&0.016&&46609.454&$-$4313&$-$0.028\\
&46298.342&4490&0.038&&47388.369&$-$2993&$-$0.009\\
V1097 Oph (1)&29787.470&$-$5&$-$0.003&&48839.392&$-$534&0.024\\
&29790.429&0&$-$0.008&&48862.378&$-$495&$-$0.002\\
&29816.518&44&0.000&&49154.493&0&0.026\\
&29844.389&91&0.012&&&&\\
\hline

\end{tabular}
\end{center}
\centerline{\normalsize $^*$ Mid-exposure times of plates with brightest observations}
\end{table}



\references

Hoffmeister, C., 1967, {\it Astron. Nachr.}, {\bf 290}, 43

Ivanij, M. B., Samus, N. N. 1994, {\it Perem. Zvezdy}, {\bf 23}, 251

Konoplyov, P. I., 1986, {\it Perem. Zvezdy}, {\bf 22}, 417

\endreferences

\IBVSedata{5539-t4.txt}
\IBVSdataKey{5539-t4.txt}{V1077 Oph}{photometry}
\IBVSedata{5539-t5.txt}
\IBVSdataKey{5539-t5.txt}{V1090 Oph}{photometry}
\IBVSedata{5539-t6.txt}
\IBVSdataKey{5539-t6.txt}{V1097 Oph}{photometry}
\IBVSedata{5539-t7.txt}
\IBVSdataKey{5539-t7.txt}{V2029 Oph}{photometry}

\end{document}

