\documentstyle[twoside,epsf]{article}

\input ibvs2.sty
\input ibvst.sty

\begin{document}

\IBVShead{4997}{6 December 2000}

\IBVStitle{CCD Light Curve and New Elements of V1823 C\lowercase{yg}}

\IBVSauth{Martignoni, M.$^1$; Acerbi, F.$^2$}

\IBVSinst{Via Don Minzoni 26, I�20020 Magnago (Milano), Italy, e-mail: maxmartignoni@libero.it}

\IBVSinst{Via Zoncada 52, I-20073 Codogno (Lodi), Italy, e-mail: acerbifr@tin.it}

\SIMBADobj{V1823 Cyg}

\begintext

\IBVSTnam{V1823 Cyg = GSC 2679.1740 = S3854 = CSV 5076 = NSV 12892}

\IBVSTcoo{20\hr 12\mm 6\fsec40}{+3\deg 38\arcm 33\farcs6}{2000.0}

\IBVSTobs{Private station in Busto Arsizio, 0.21-m Newton ($F/5.0$)}

\IBVSTdet{DTA Seti 245C CCD Camera}

\IBVSTfil{None}

\IBVSTcomp{GSC 2679.0670 (10\fmm83)}

\IBVSTchk{GSC 2679.2602 (11\fmm5)}

\IBVSTsysn

\IBVSTdata{Through IBVS Web-site}

\IBVSedata{4997-t1.txt}

\IBVSTtyp{ EW }

\IBVSfig{9.55cm}{4997-f1.ps}{CCD light curve of V1823 Cyg folded with the elements given in (1)}

\IBVSTrem{
V1823 Cyg was discovered as variable star by Hoffmeister (1949) and
first observed by Ahnert-Rohlfs et al.\ (1954) who suspected an EW or
RRc type of variation.  It was monitored visually by some members of
the G.E.O.S. (Wils, 1984): they found a probable RR Lyrae nature and
gave also an approximate periodicity.  We observed V1823 Cyg during
1999 and 2000 seasons: on the basis of the 409 measures obtained on 12
nights from JD 2451374 to JD 2451841 we were able to determine new type
of variability (EW) and derived the following new elements of
variation:
\begin{equation}
{\rm Min(I) = HJD}~2451841.3487 + 0\fday 84627 \times E.
\end{equation}
Five times of minimum light are reported below:
\begin{center}
\begin{tabular}{cr@{.}lr@{.}l}
\hline
HJD  & \multicolumn2c{$E$ (1)} & \multicolumn2c{$O-C$ (1)} \\
\hline
2451400.4444 & $-521$&0 & +0&0024 \\
2451458.4092 & $-452$&5 & $-0$&0023 \\
2451810.4607 & $-36$&5 & +0&0009 \\
2451813.4187 & $-33$&0 & $-0$&0031 \\
2451841.3487 & 0&0 & 0&0000 \\
\hline
\end{tabular}
\end{center}
}
 
\references
Ahnert-Rohlfs, E., et al., 1954, {Ver\"offentl.\ der Sternwarte in Sonneberg}, 
Band 2, Heft 2

Hoffmeister, C., 1949, {\it Astronomische Abhandlungen, Erg\"anzungshefte zu 
den Astronomi\-sche Nachrichten}, Band 12, Nr.\ 1

Wils, P., 1984, {\it Note Circulaire GEOS NC}, 427

\endreferences

% from IBVS 5259
\IBVSerratum{4997}


The declination of V1823 Cyg is, of course, +34\deg 38\arcm 33\farcs6 instead 
of the +3\deg ... printed in the paper. 

\bigskip
\bigskip

The Editors

\end{document}

