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[vsnet-preprint 46] TmzV34 preprint
TmzV34 preprint
The following article is accepted for publication as IBVS No. 5123.
The figures are available at:
http://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/preprints/TmzV34/
Regards,
Taichi Kato
===
\documentstyle[twoside,epsf]{article}
\input{ibvs2.sty}
\def\h{\hbox{$\!^{\rm h}$}}
\def\m{\hbox{$\!^{\rm m}$}}
\def\s{\hbox{$\!^{\rm s}$}}
\def\deg{\hbox{$\!^\circ$}}
\def\arcm{\hbox{$^{\prime}$}}
\def\arcs{\hbox{$\!\!^{\prime\prime}$}}
\def\fs{\hbox{$.\!\!^{\rm s}$}}
\begin{document}
\IBVShead{xxxx}{xx June 2001}
\IBVStitletl{Outburst Photometry of T\lowercase{mz}V34}
\IBVSauth{Kato,~Taichi$^1$, Uemura,~Makoto$^1$, Buczynski,~Denis$^2$, Schmeer,~Patrick$^3$}
\vskip 5mm
\IBVSinst{Dept. of Astronomy, Kyoto University, Kyoto 606-8502, Japan,
e-mail: (tkato,uemura)@kusastro.kyoto-u.ac.jp}
\IBVSinst{Conder Brow Observatory, Littlefell Lane, Lancaster LA2 ORQ,
England,
e-mail: denis@cb978iau.demon.co.uk}
\IBVSinst{Bischmisheim, Am Probstbaum 10, 66132 Saarbr\"{u}cken, Germany,
e-mail: extpasc@rz.uni-sb.de}
\IBVSobj{TmzV34}
\IBVStyp{UGSS}
\IBVSkey{dwarf nova, photometry}
\begintext
TmzV34 is a variable star discovered by Takamizawa (Takamizawa 1998).
The J2000.0 coordinates are 09\h 15\m 51\fs 69, +09\deg 00\arcm 49\farcs 9.
Although Takamizawa's initial observations (1998) suggested rather irregular
variations, a noticeable brightening to 13.1 mag was recored on films
taken 1994 November 30. The star was also likely identified with the
ROSAT source 1RXS J091552.3+090056 = RX J0915.8+0900, which led to a
possible classification as a cataclysmic variable. The ROSAT source was
independently identified with the same star through the Hamburg/RASS Optical
Identifications (Bade et al. 1998). The star was also recorded bright
($V$=12.99) in GSC, which made the dwarf nova-type variability likely.
Since then, the star has been monitored as a part of VSNET Collaboration
(http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/).
The first outburst since the discovery was detected by T. Watanabe
(Watanabe 1999) at visual magnitude 13.6 on 1999 April 8, which made
the secure identification of the variable as a dwarf nova. This outburst,
however, was not fully followed because of the unfavorable observing
condition.
\vskip 3mm
The next outburst detection was made by one of the authors (P. Schmeer),
who observed the object using the Iowa Robotic Observatory (IRO)
0.5-m telescope and an AP-8 CCD, and found it slowly brightening from
unfiltered CCD magnitude of 15.4 on 2000 February 3.444 UT to 14.2 on
February 8.319 UT (Schmeer 2000). Upon this detection, we started
time-resolved CCD photometry.
The CCD observations at Kyoto University were done using an unfiltered ST-7
camera attached to the Meade 25-cm Schmidt-Cassegrain telescope.
The exposure time was 30 s. The images were dark-subtracted, flat-fielded,
and analyzed using the Java$^{\rm TM}$-based aperture photometry package
developed by one of the authors (TK). The CCD observations at Conder Brow
Observatory were done using an SXL8 CCD attached to a 33-cm reflector.
The exposure time was 45 s. The Kyoto and Conder Brow observations
used different comparison stars, GSC 819.542 (GSC magnitude 13.07) and
GSC 819.281 (GSC magnitude 13.41), respectively, because of the different
field-of-view of the images. We therefore treat these observations
separatedly. Barycentric corrections were applied to the observed times
before the following analysis. Table 1 lists the log of observations,
together with nightly averaged magnitudes. Table 2 lists the snapshot
observations by P. Schmeer.
\begin{table}
\begin{center}
Table 1. Log of time-series observations of TmzV34 \\
\vspace{10pt}
\begin{tabular}{cccccc}
\hline
start$^a$ & end$^a$ & mean mag$^b$ & error$^c$ & N$^d$ & Observatory \\
\hline
51584.228 & 51584.296 & 0.234 & 0.014 & 82 & Kyoto \\
51585.195 & 51585.335 & 0.611 & 0.012 & 221 & Kyoto \\
51585.388 & 51585.517 & 0.320 & 0.006 & 168 & Conder Brow (CB)\\
\hline
\end{tabular}
\end{center}
\hskip 15mm $^a$ BJD$-$2400000
\hskip 15mm $^b$ Magnitude relative to GSC 819.542 (Kyoto) or GSC 819.281
(CB)
\hskip 15mm $^c$ Standard error of nightly average
\hskip 15mm $^d$ Number of frames
\end{table}
\begin{table}
\begin{center}
Table 2. Snapshot observations of TmzV34 \\
\vspace{10pt}
\begin{tabular}{cc}
\hline
BJD-2400000 & unfiltered CCD mag \\
\hline
51577.949 & 15.4 \\
51578.797 & 15.2 \\
51579.824 & 15.1 \\
51581.938 & 14.4 \\
51582.824 & 14.2 \\
51584.811 & 14.0 \\
\hline
\end{tabular}
\end{center}
\end{table}
\IBVSfig{10cm}{fig1.ps}{Light curves of Kyoto Observations. The relatively
large scatter was due to passing clouds.}
\IBVSfig{8cm}{fig2.ps}{Light curves of Conder Brow Observations}
\vskip 3mm
Figure 1 and 2 show the result of Kyoto and Conder Brow Observations,
respectively. The Kyoto observations show only slow fading, and the
fading almost stopped in the Conder Brow Observations.
No apparent superhumps were detected. The Kyoto observations having
been affected by clouds, the Conder Brow observations (Figure 2) more
adequately represent the absence of regular superhump-type oscillations.
These observations qualifies TmzV34 as an SS Cyg-type (UGSS in GCVS)
dwarf nova. The slow rising at an almost constant rate of 0.22 mag
d$^{-1}$ (as calculated from Table 2) also supports the SS Cyg-type
classification. The low outburst amplitude and the slow rise make
TmzV34 as a good candidate for a dwarf nova with a long orbital period.
\vskip 3mm
The authors are grateful to VSNET members for providing visual observations
covering years. P. Schmeer's observations were made with the Iowa
Robotic Observatory, and he wishes to thank Robert Mutel and his students.
Part of this work is supported by a Research Fellowship of the
Japan Society for the Promotion of Science for Young Scientists (MU).
\references
Bade, N., Engels, D., Voges, W., Beckmann, V., Boller, Th., Cordis, L.,
Dahlem, M., Englhauser, J., Molthagen, K., Nass, P., Studt, J.,
Reimers, D., 1998, A\&AS, 127, 145
Schmeer, P., 2000, {\it VSNET alert circulation}, No. 4160 \\
(available from
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/alert4000/msg00160.html).
Takamizawa, K., 1998, {\it VSNET observations}, No. 10504 \\
(available from
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/obs10000/msg00504.html).
Watanabe, T., Kato, T., 1999, {\it VSNET alert circulation}, No. 2854 \\
(available from
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/alert2000/msg00854.html).
\end{document}
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