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\IBVShead{5326}{29 October 2002}

\IBVStitle{Identification of V735 Sagittarii}

\IBVSauth{Yoshida, S.$^1$; Kadota, K.$^2$; Kato, T.$^3$; Hazen, M. L.$^4$; Henden, A. A.$^5$}

\IBVSinst{MISAO Project, 2-4-10-708 Tsunashima-nishi Kohoku-ku Yokohama City Kanagawa 223-0053, Japan,\\ \indent e-mail: comet@aerith.net}
\IBVSinst{MISAO Project, 791-8, Koshikiya, Ageo, Saitama-ken, 362-0064 Japan,\\ \indent e-mail: kenic-k@astroarts.co.jp}
\IBVSinst{Dept.\ of Astronomy, Kyoto University, Kyoto 606-8502, Japan, e-mail: tkato@kusastro.kyoto-u.ac.jp}
\IBVSinst{Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA, e-mail: mhazen@cfa.harvard.edu}
\IBVSinst{Universities Space Research Association/U. S. Naval Observatory, Flagstaff, AZ 86001 USA,\\ \indent email: aah@nofs.navy.mil}

\SIMBADobj{V735 Sgr}
\IBVSabs{This report discusses the identification of V735 Sgr.}


\begintext

V735 Sgr is a variable star discovered by Luyten in the course of the
Bruce Proper Motion Survey (Luyten 1936).
The variable was reported at coordinates R.A. 17\hr53\fmm5,
Dec. $-$29\deg33\arcm \ (1900.0) with a blue photographic brightness
variation between 14.2 -- 15.5 mag.

Plaut gave a finding chart for the variable (Plaut 1948).
However, at the position marked on that chart, there is a close pair of
stars (7 arcsec separation).
The astrometry of the two stars by Henden (using USNO-A2.0) are:
\begin{center}
\begin{tabular}{l}
R.A. 17\hr59\mm51\fsec79, Dec. $-$29\deg33\arcm55\farcs7 (2000.0) $\cdots$ star N \\
R.A. 17\hr59\mm52\fsec03, Dec. $-$29\deg34\arcm01\farcs7 (2000.0) $\cdots$ star S \\
\end{tabular}
\end{center}

Vogt and Bateson observed V735 Sgr in outburst and identified the
variable as ``the south-eastern component of a close pair'' (Vogt and
Bateson 1982). 
The listing for V735~Sgr in the General Catalog of Variable Stars (GCVS)
is based on their observations, with the star classified as having
irregular short variations, with coordinates of R.A. 17\hr59\mm52\sec,
Dec. $-$29\deg33\farcm8 (2000.0), and photographic brightness
variations between 13.5 -- 16.5 mag.

Hazen investigated the Bruce plate marked by Luyten, and found that the
brightness of star N differs between two plates, whereas the brightness
of star S does not differ.

Henden observed this pair in 1999 July and August, using the 1.0-m
telescope at USNO Flagstaff Station.
Table 1 shows the photometry. 
The brightness variation of star N confirms the Luyten identification.
On the other hand, star S is constant within the photometric errors.  
The $B-V$ colour of star N is not particularly red, so does not conflict
with the classification in the GCVS.

In conclusion, the remark by Vogt and Bateson was a mistake and V735 Sgr
is the north-western component of this pair. 
Figure 1 shows an accurate chart identifying V735~Sgr.


\begin{center}
{\normalsize Table 1: Henden photometry of the pair} \\
\begin{tabular}{cccc} \hline
Star & HJD & $V$ mag & $B-V$ \\ \hline
N & 2451379.8048 & $14.775 \pm 0.009$ & $0.801 \pm 0.010$ \\
N & 2451380.7678 & $14.507 \pm 0.006$ & $0.827 \pm 0.007$ \\
N & 2451402.6682 & $14.697 \pm 0.007$ & $0.785 \pm 0.009$ \\
S & 2451379.8048 & $14.748 \pm 0.005$ & $0.892 \pm 0.007$ \\
S & 2451380.7678 & $14.771 \pm 0.005$ & $0.881 \pm 0.007$ \\
S & 2451402.6682 & $14.759 \pm 0.005$ & $0.878 \pm 0.006$ \\
\hline
\end{tabular}
\end{center}

\IBVSfig{70mm}{5326-f1.eps}{$V$-band chart of V735 Sgr}
%\IBVSfigKey{5326-f1.eps}{V735 Sgr}{finding chart}


\references

Luyten, W. J., 1936, {\it Astron.\ Nachr.}, {\bf 261}, 451

Plaut, L., 1948, {\it Leiden Annals}, {\bf 20}, 1

Vogt, N., Bateson, F. M., 1982, {\it A\&AS}, {\bf 48}, 383

\endreferences


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