\documentstyle[twoside, epsf, amssymb]{article}

\input ibvs2.sty

\begin{document}
\IBVShead{5569}{14 October 2004}

\IBVStitle{New SU UM\lowercase{a}-Type Dwarf Nova V344 P\lowercase{av}}


\IBVSauth{UEMURA, M.$^{1,2}$; MENNICKENT, R.$^{1}$; STUBBINGS, R.$^{3}$}

\IBVSinst{Departamento de F\'{\i}sica, Facultad de Ciencias F\'{\i}sicas
y Matem\'aticas, Universidad de Concepci\'on, Casilla 160-C,
Concepci\'on, Chile, e-mail: muemura@cepheid.cfm.udec.cl}
\IBVSinst{Yukawa Institute for Theoretical Physics, Kyoto University,
Kyoto 606-8502, Japan}
\IBVSinst{19 Greenland Drive, Drouin 3818, Victoria, Australia}

\SIMBADobjAlias{V344 Pav}{FAUST 4455}
\IBVStyp{ UGSU }
\IBVSkey{photometry}
\IBVSabs{We performed time-series observations of a dwarf nova V344 Pav}
\IBVSabs{during the outburst on 2004 August.}
\IBVSabs{The object showed superhumps, which establish that the object}
\IBVSabs{is a new SU UMa-type dwarf nova.}
\IBVSabs{We calculate the superhump period to be 0.079607(82) d}
\IBVSabs{In conjunction with the reported supercycle of V344 Pav, the}
\IBVSabs{relatively long superhump period indicates that it is one of ordinary}
\IBVSabs{SU UMa stars.}


\begintext

Maza~\&~Hamuy (1990) reported the discovery of a dwarf nova in outburst at 
$m_{\rm pg}=14.5$ in Pavo, which was designated as V344~Pav in 
Kazarovets~et~al. (1993).  Mason~\&~Howell (2003) reported a quiescent
spectrum of V344~Pav, which exhibits typical features of dwarf nova in
quiescence.  Its quiescent magnitude was estimated to be $\lesssim
20$~mag.  According to Mason~\&~Howell (2003), the object was $V=19.4$
at the time of their spectroscopic observation.  Based on a relatively
large amplitude of outburst, they commented that V344~Pav is likely a
WZ~Sge-type dwarf nova, or a TOAD (Tremendous Outburst Amplitude Dwarf
novae; Howell~et~al. 1995).

An outburst of V344~Pav was reported to the VSNET on
JD~2453233.04 at a visual magnitude of 14.4.  We then initiated CCD
time-series photometric observations at Universidad de Concepci\'on.  We
used a Meade 30-cm Schmidt-Cassegrain telescope and an unfiltered
ST-7XMEI camera.  After correcting for the standard de-biasing and flat
fielding, we performed the PSF photometry for the images.  The
differential magnitudes of the variable were measured against
UCAC2~04225816 (11.42~mag in the UCAC system), whose constancy during
the run was confirmed by UCAC2~04225753 (12.96~mag in the UCAC system).
The log of observations is shown in table 1.  Heliocentric corrections
were applied before the period analysis.

\begin{table}[!hb]
\centerline{Table 1. Observation log.}
\begin{center}
\begin{tabular}{cccr}
\hline
$T_{\rm start}$ (HJD) & $\Delta T$ (hr) & mag. & N \\
\hline
2453235.5377 & 2.08 & $3.996\pm 0.005$ & 230\\
2453236.5829 & 6.09 & $4.307\pm 0.003$ & 673\\
2453237.5355 & 4.86 & $4.902\pm 0.008$ & 535\\
2453238.5337 & 3.92 & $6.498\pm 0.027$ & 438\\
2453239.5339 & 3.57 & $7.235\pm 0.046$ & 391\\
2453240.5290 & 1.84 & $7.432\pm 0.078$ & 203\\
2453241.5270 & 1.71 & $7.341\pm 0.076$ & 183\\
2453242.5263 & 0.86 & $7.614\pm 0.106$ &  98\\
2453250.5350 & 1.32 & $7.943\pm 0.191$ &  92\\
2453256.5259 & 1.45 & $7.890\pm 0.093$ & 162\\
\hline
\end{tabular}
\end{center}
\end{table}

\IBVSfig{8cm}{5569-f1.eps}{The overall light curve of the superoutburst of
V344~Pav in August 2004.  The abscissa and ordinate denote the time in
HJD and the differential magnitude against a comparison star
UCAC2~04225816 (11.42~mag in the UCAC system), respectively.} 
\IBVSfigKey{5569-f1.eps}{V344 Pav}{light curve} 

Figure~1 shows the overall light curve during the outburst.  The object
was gradually fading with a rate of 0.28~mag\,d$^{-1}$ for the first two
days, then entered a rapid fading phase on JD~2453237.  After the rapid
fading, the object returned to a quiescent level within 10~days.  In the
last two observations, the differential magnitudes are $\sim 7.9$~mag,
which indicates that the quiescent magnitude is around 19.3~mag if we use 
the UCAC2~magnitude of the comparison star (11.42~mag).  

Enlarged light curves are shown in Figure~2.  Our observation clearly detects
repetitive humps having amplitudes of 0.15~mag during the outburst, as
can be seen in Figure~2.  We performed a period analysis with the PDM method
using the light curve between JD~2453235 and 2453237 (Stellingwerf 1978).
Figure~3 is the resultant frequency--$\Theta$ diagram.  The
best period is calculated to be $0.079607\pm 0.000082$~d.  Figure~4
shows phase-averaged profiles of the humps on JD~2453235, 2453236, and
2453237.  As can be seen from this figure, humps appeared even in
JD~2453237, during the rapid fading stage.  Secondary maxima appear
in the hump profiles around the phase 0.4--0.5 in JD~2453235 and
2453236.

\IBVSfig{10cm}{5569-f2.eps}{Enlarged light curves during the superoutburst of
V344~Pav.  The magnitude scales of JD 2453236 and 2453237 are shifted by
$+0.2$ and $+0.4$~mag, respectively.}
\IBVSfigKey{5569-f2.eps}{V344 Pav}{light curve} 

\vspace*{-0.4cm}

Although the observed duration of the outburst is short (3~d), features
of the overall light curve and the humps resemble those of
superoutbursts in SU~UMa-type dwarf novae (cf. Warner 1985).  We hence
conclude that V344~Pav is an SU~UMa~type dwarf nova having a superhump
period of $0.079607\pm 0.000082$~d.  It is possible that, at the time of
the outburst detection, it had already been in a late phase of
superoutburst.  This is consistent with the presence of the secondary
maximum in superhump profiles (Figure~4), since it generally appears in
a late superoutburst phase.  The outburst amplitude is $> 3.9$~mag, and
probably $\sim 5$~mag if one assumes a typical properties of
superoutburst, that is, a fading rate of $\sim 0.1\;{\rm mag}\; {\rm d}^{-1}$
and a duration of about two weeks (Warner 1985).  

\IBVSfig{10cm}{5569-f3.eps}{Frequency--$\Theta$ diagram calculated with the
PDM method for superhumps in V344~Pav.} 
\IBVSfigKey{5569-f3.eps}{V344 Pav}{} 

\IBVSfig{10cm}{5569-f4.eps}{Average superhump profiles.  The magnitude
scales of JD 2453236 and 2453237 are shifted by $+0.2$ and $+0.4$~mag,
respectively.}
\IBVSfigKey{5569-f4.eps}{V344 Pav}{} 

\vspace*{-0.8cm}

The superhump period of V344~Pav is a typical one for ordinary SU~UMa
stars, rather than WZ~Sge-type stars having very short periods, except
for RZ~Leo (Ishioka~et~al. 2001).  The ordinary SU~UMa-type nature for 
V344~Pav is also supported by its relatively high frequency of outbursts.  
According to Mason~\&~Howell (2003), outbursts of V344~Pav are recorded in
September 1983 ($m_{\rm pg}=14.5$), March 1984 ($m_{\rm pg}=16$), July
1990 \linebreak($m_{\rm pg}=14.5$), September 1999 ($m_{\rm vis}=14.3$), July and
September 2000 ($m_{\rm vis}=14.6$ and $14.4$), and May 2001 ($m_{\rm
vis}=14.3$).  In the VSNET data base, we find an additional outburst
records in September 2003 ($m_{\rm vis}=14.4$).  In conjunction with the
superoutburst in this paper (August 2004; $m_{\rm vis}=14.5$), the
supercycle is probably 1--2 years, much shorter than those of
WZ~Sge-type stars ($\gtrsim 10$ years).  The faint outburst in March
1984 may be a normal outburst, which implies that a number of normal
outbursts have been overlooked.

\references

Howell, S. B., Szkody, P., \& Cannizzo, J. K., 1995, {\it ApJ}, {\bf
439}, 337 
%%\BIBCODE{1995ApJ...439..337}

Ishioka, R., Kato, T., Uemura, M., Iwamatsu, H., Matsumoto, K.,
Stubbings, R., Mennickent, R., \& Billings, G. W., 2001, {\it PASJ},
{\bf 53}, 905 
%%\BIBCODE{2001PASJ...53..905I}

Kazarovets, E. V., Samus, N. N., \& Goranskij, V. P., 1993, {\it IBVS}, 3840
%%\BIBCODE{1993IBVS.3840....1K}

Mason, E., \& Howell, S. B., 2003, {\it A\&A}, {\bf 403}, 699 
%%\BIBCODE{2003A&A...403..699M}

Maza, J., \& Hamuy, M., 1990, {\it IAUC}, 5073 
%%\BIBCODE{1990IAUC.5073....2M}

Stellingwerf, R. F., 1978, {\it ApJ}, {\bf 224}, 953 
%%\BIBCODE{1978ApJ...224..953}

Warner, B., 1985, in Interacting Binaries, ed. P. P. Eggleton, \& J. E. Pringle (Dordrecht: D. Reidel Publishing Company), 367 
%%\BIBCODE{1985ib...proc..367W}

\endreferences

\end{document}
