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\input{ibvs2.sty}

\begin{document}

\IBVShead{5607}{4 March 2005}

\IBVStitle{Three 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@4pisysteme.de, pk@4pisysteme.de}}

\SIMBADobj{V820 Oph}
\SIMBADobj{NSV 10140}
\SIMBADobj{NSV 10478}

\begintext

These stars were reported to be RR Lyrae Variables by Boyce and Huruhata
(1942) and Hoffmeister (1966); no ephemeris were published until today. 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 to 1994, were used to check
the behaviour of these objects (see Table 1).

The elements listed below were obtained by means of least-squares solutions. Photographic
amplitudes were derived with respect to magnitudes of the comparison
stars given in Table 2.

\vskip 3mm
\parindent0mm
{\em Remarks:}
\vskip 3mm
{\em V820 Oph}

Elements valid for J.D. 2429100-2443300 and J.D. 2443700-2449500 resp.

\vskip 3mm
{\em NSV 10140}

Elements valid for J.D. 2429100-2445000 and J.D. 2445000-2449500 resp.
Nine times of maxima out of the second set (observed between J. D. 2445530 and J.D. 2446642)
were also used to derive a meaningful
period value for the first set of elements. Although this is quite arbitrary, it has
turned out to be the only method to include the early observations in a good composite light
curve as shown in \mbox{Fig. 4}.  For this reason, ephemeris[1] should be used as preliminary because the true
period change might be stronger than derived in this paper.

\vskip 3mm
{\em NSV 10478}

Due to the availability of additional older plates, a total number of 269 plates (J.D.~2425324-2449488) was used to examine this star. Elements given below are
at least valid
for an interval of JD 2436800-2449500. Unfortunately the distribution of the older plates
is insufficient to determine a date of the period change as well as the value of the period
acting in the time before the interval mentioned above.


\vskip 3mm

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




\IBVS2fig{7cm}{5607-f1.eps}{Composite light curve of V820 Oph}{5607-f2.eps}{(O$-$C) diagram for V820 Oph}
\IBVSfigKey{5607-f1.eps}{V820 Oph}{light curve}
\IBVSfigKey{5607-f2.eps}{V820 Oph}{O-C diagram}

\IBVS2fig{7cm}{5607-f3.eps}{Composite light curve of NSV 10140}{5607-f4.eps}{(O$-$C) diagram for NSV 10140}
\IBVSfigKey{5607-f3.eps}{NSV 10140}{light curve}
\IBVSfigKey{5607-f4.eps}{NSV 10140}{O-C diagram}

\IBVS2fig{7cm}{5607-f5.eps}{Light curve of NSV 10478 (J.D. 2436840 - 2449488)}{5607-f6.eps}{(O$-$C) diagram for NSV 10478}
\IBVSfigKey{5607-f5.eps}{NSV 10478}{light curve}
\IBVSfigKey{5607-f6.eps}{NSV 10478}{O-C diagram}


\begin{table}[!ht]
\centerline{Table 1. Summary of this paper}
\vskip 3mm
\begin{center}
\begin{tabular}{lcrrrrcc}
\hline
Star   & Type &  Epoch    &Period &Max. & Min. & M$-$m & No. of \\
       &      & 2400000+ & (day)  &     &      &     & Plates   \\
\hline
V820 Oph (1) & RRab  &29785.399     & 0.3905520      & 14\fmm7 & 15\fmm7  & 0\fper22 &105 \\
             &       &   $\pm$8     &    $\pm$4      &         &          &          &\\
V820 Oph (2) &       &47379.431     & 0.3905686      &         &          &          &96 \\
          &          &   $\pm$7     &   $\pm$24      &         &          &          &\\
NSV 10140(1) & RRab  &39678.430     & 0.4900743      & 15\fmm8 & 17\fmm1  &0\fper17  &98 \\
             &       &   $\pm$7     &    $\pm$8      &         &          &          &\\
NSV 10140(2) &       &49127.454     & 0.4900573      &         &          &          &68 \\
             &       &  $\pm$13     &   $\pm$25      &         &          &          &\\
NSV 10478    & RRab  &49124.451     & 0.4520359      & 14\fmm7 & 15\fmm7  & 0\fper25 &175 \\
             &       &  $\pm$11     &    $\pm$8      &         &          &          &\\

\hline

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


\begin{table}[!hb]
\centerline{Table 2. Comparison stars and cross references}
\vskip 3mm
\begin{center}
\begin{tabular}{ccrcr}
\hline
    &  V820 Oph           &     &  NSV 10140         &\\
    &  HV 11033           &     &  S 9288          &\\
    &  USNO 0900-10444265 &     &  USNO 0900-11438187&\\
\hline
Comp. No.  &  USNO      & m$^*$     & USNO      & m$^*$\\
\hline
1   &  0900-10436768 &  14\fmm6  & 0900-11441724 & 15\fmm7\\
2   &  0900-10454891 &  14\fmm9  & 0900-11433031 & 15\fmm8\\
3   &  0900-10451472 &  15\fmm0  & 0900-11442001 & 16\fmm3\\
4   &  0900-10441376 &  16\fmm1  & 0900-11439742 & 17\fmm4\\
\hline
&&&&\\
&&&&\\
\hline
    & NSV 10478          &       &               &\\
    & S 9302             &       &               &\\
    & USNO 0900-12232376 &       &               & \\
\hline
Comp. No.  &  USNO       & m$^*$ &               & \\
\hline
1   & 0900-12246201 & 14\fmm2&                   &  \\
2   & 0900-12233841 & 14\fmm8&                   &  \\
3   & 0900-12226131 & 15\fmm4&                   &   \\
\hline

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


\clearpage

\begin{table}[!ht]
\centerline{\normalsize Table 3. Heliocentric times of maxima and $O-C$ values according to the elements derived in this paper.}
\vskip 3mm
\begin{center}
\begin{tabular}{lcrrlcrr}
\hline
Star   &  JD (max.$^*$) &Epoch &$O-C$  &  Star   &  JD (max.$^*$) &Epoch &$O-C$  \\
\hline
V820 Oph (I)&29785.410&0&0.011&NSV 10140 (II)&46506.628&$-$5348&0.001\\
&29788.511&8&$-$0.013&&46507.630&$-$5346&0.023\\
&29808.450&59&0.008&&46642.386&$-$5071&0.013\\
&29844.389&151&0.016&&47380.399&$-$3565&0.000\\
&31696.347&4893&$-$0.023&&47381.387&$-$3563&0.008\\
&39671.44&25313&$-$0.003&&48067.449&$-$2163&$-$0.011\\
&39678.450&25331&$-$0.023&&49124.489&$-$6&$-$0.024\\
&39685.480&25349&$-$0.023&&49127.474&0&0.020\\
&40354.534&27062&0.016&NSV10478&25406.445&$-$52469&$-$0.133\\
&40381.472&27131&0.006&&25687.614&$-$51847&$-$0.131\\
&40383.442&27136&0.023&&26427.603&$-$50210&$-$0.125\\
&41150.468&29100&0.005&&26475.511&$-$50104&$-$0.132\\
V820 Oph (II)&46271.400&$-$2837&0.012&&26504.454&$-$50040&$-$0.120\\
&46289.368&$-$2791&0.014&&36840.321&$-$27175&$-$0.054\\
&46298.342&$-$2768&0.005&&37820.433&$-$25007&0.044\\
&46608.449&$-$1974&0.001&&38883.550&$-$22655&$-$0.027\\
&46974.430&$-$1037&0.019&&38936.465&$-$22538&$-$0.001\\
&47368.474&$-$28&$-$0.021&&39270.525&$-$21799&0.005\\
&47379.401&0&$-$0.030&&39289.463&$-$21757&$-$0.043\\
&47415.349&92&$-$0.014&&39681.420&$-$20890&$-$0.001\\
&48801.513&3641&0.022&&39685.503&$-$20881&0.014\\
&48862.378&3797&$-$0.042&&40383.442&$-$19337&0.009\\
&49124.489&4468&$-$0.003&&40426.441&$-$19242&0.065\\
&49488.539&5400&0.037&&44484.340&$-$10265&0.038\\
NSV 10140 (I)&38883.550&$-$1622&0.020&&46288.406&$-$6274&0.028\\
&38910.515&$-$1567&0.031&&46298.342&$-$6252&0.019\\
&39648.507&$-$61&$-$0.029&&46507.630&$-$5789&0.015\\
&39651.484&$-$55&0.008&&46554.584&$-$5685&$-$0.043\\
&39678.428&0&$-$0.002&&46646.396&$-$5482&0.006\\
&40417.432&1508&$-$0.030&&46884.600&$-$4955&$-$0.013\\
&40418.435&1510&$-$0.007&&47366.446&$-$3889&$-$0.037\\
&40419.430&1512&0.007&&47381.376&$-$3856&$-$0.025\\
&40473.320&1622&$-$0.011&&47385.422&$-$3847&$-$0.047\\
NSV 10140 (II)&45530.427&$-$7340&$-$0.006&&47386.383&$-$3845&0.010\\
&45822.489&$-$6744&$-$0.018&&47390.393&$-$3836&$-$0.048\\
&46270.460&$-$5830&0.041&&47391.347&$-$3834&0.002\\
&46271.400&$-$5828&0.000&&47415.349&$-$3781&0.046\\
&46296.356&$-$5777&$-$0.036&&49124.489&0&0.038\\
&46298.342&$-$5773&$-$0.011&&&&\\
\hline

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

\references

Hoffmeister, C., 1966, {\it Astron. Nachr.}, {\bf 289}, 139

Boyce, Hughes, E., Huruhata, M., 1942, {\it Harvard Annals}, {\bf 109}, {No. 4}, 19 
%Orig: Hughes-Boyce, E., Huruhata, M., 1942, {\it Harvard Annals}, {\bf 109}, 4
%Corrected: Fri Mar 25 12:59:10 MET 2005

\endreferences


\IBVSedata{5607-t4.txt}
\IBVSdataKey{5607-t4.txt}{NSV 10140}{photometry}
\IBVSedata{5607-t5.txt}
\IBVSdataKey{5607-t5.txt}{NSV 10478}{photometry}
\IBVSedata{5607-t6.txt}
\IBVSdataKey{5607-t6.txt}{V820 Oph}{photometry}

\vfill

%From: IBVS 5728
\IBVSerratum{5607}

The correct identifier for NSV 10478 is USNO 0900-12232367.

\bigskip
\bigskip

The Editors

\end{document}

