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KL Dra superoutburst?
We have received information from Matt Wood (Florida Institute of
Technology) that the helium dwarf nova KL Dra appears to be undergoing
a superoutburst.
The object was observed in outburst in 2001 July-August (M. Wood,
vsnet-alert 6167, see also vsnet-alert 6168). If the object is indeed
undergoing a superoutburst, the supercycle could be around 300 d or
its 1/N. Although the 2001 August outburst was not followed in detail
because of the "ultra-outburst" of WZ Sge, Franco Mallia and Gianluca Masi
reported time-series photometry (vsnet-campaign-dn 1172). The object
had been a long-term target of the VSNET collaboration since its
discovery by M. Schwarz (originally named SN 1998di).
The present likely superoutburst would provide an ideal opportunity
to study the details of its superhumps (period 1527 s), whose evolution
is expected to follow the course as in CR Boo or V803 Cen (sharp superoutburst
maximum, followed by a dip, then rebrightening to a plateau - oscillation
state? A representative long-term light curves can be found in Kato et al.
(2000) MNRAS 315, 140; Kato et al. (2000) IBVS 4915). So even if the object
is observed fainter than expected, please don't hesitate to make a
second-night observation!
===
Wood's information in vsnet-alert in 2001:
We observed KL Draconis, a suspected CR Boo star, on 7/31/01 UT. We found
it in high state (mag 16.7 or so) and observed superhumps with a period of
25 minutes (1527 s), which is remarkably close to the 1490s period for CR
Boo. Our observations were taken with an Apogee AP7p CCD at the SARA
0.9-m observatory at Kitt Peak National Observatory. We used 90 second
integrations and no filter. There was cirrus present, but the
differential light curve is good. Observers were Matt Wood and Matt
Casey.
Our light curve from that night and the Fourier transform are available at
www.astro.fit.edu/wood
The star was originally thought to be a supernova, and it's original
designations was sn1998di, however a spectrum showed it to be similar to
the AM CVn class of stars. The classification spectrum is available at:
http://oir-www.harvard.edu/cfa/oir/Research/supernova/images/sn98di.gif
We're writing up a short Letter to announce the period determination, but
I know many of you will be interested to know this result sooner rather
than later. If anyone has access to a 1-m class telescope and can get
more time series observations in the next few days, that would be very
useful. Our telescope is now shutdown for the next month.
The reductions are a little difficult becuase KL Dra in front of a galaxy,
so when it in low state (mag 20), it begins to blend in with the galaxy
and is very tough to get photometry.
===
For KL Dra (SN1998di) observers, the following VSNET page would be
helpful.
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/DNe/sn1998di.html
Please use high-resolution images to separate the variable from the
galaxy.
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vsnet-adm@kusastro.kyoto-u.ac.jp
