[vsnet-preprint 94] V735 Sgr preprint

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

V735 Sgr preprint

   Posted on behalf of Yoshida-san.

   The followin paper will appear as IBVS No. 5326.

   The PostScript files are placed at:
   http://vsnet.kusastro.kyoto-u.ac.jp/pub/vsnet/preprints/V735_Sgr/

Regards,
Taichi Kato

==

\documentstyle[twoside,epsf]{article}

\input{ibvs2.sty}

\begin{document}

\IBVShead{0000}{24 October 2002}

\IBVStitletl{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, email: aah@nofs.navy.mil}

\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\hr53.5\mm,
Decl. $-$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, Decl. $-$29\deg33\arcm55\farcs7 (2000.0) $\cdots$ star N \\
R.A. 17\hr59\mm52\fsec03, Decl. $-$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,
Decl. $-$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 $B-V$ color 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.

\references

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

Plaut, L., 1948, Leiden Annals 20, 1

Vogt, N., Bateson, F. M., 1982, {\it As. Ap. Sup.} {\bf 48}, 383

\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}{v735sgrv.eps}{V-band chart of V735 Sgr}

\end{document}

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