[vsnet-campaign-news 109] AstroAlert: ultra-short period dwarf nova!

[Taichi Kato <tkato>]

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              Ultra-Short Period SU UMa-type Dwarf Nova
                         in Superoutburst
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    Patrick Schmeer (Germany) reported the discovery of an outburst of
the ROSAT X-ray source 1RXS J232953.9+062814, which had been identified by
Jingyao, H. et al. (1998) as a dwarf nova.

    Upon this alert, the VSNET Collaboration team started a campaign on
this object, and revealed that the object is an SU UMa-type dwarf nova
with an extremely short (0.04633 d) superhump period.  This period is
well below the famous CV period minimum, and there is only other known
system (V485 Cen) having similar characters.  In addition to this
extreme character, 1RXS J232953.9+062814 is exceptionally bright,
reaching 12.5 at maximum, well within reach of visual observations, or
small telescope + CCD.

    CCD observers are strongly requested to observe this target as frequently
as possible (every 30 sec or so), in order to record superhumps.  The present
outburst will not long very long (probably less than 10 d), so emergent
observation is requested.

    The object is located at RA = 23h29m54s.30, Dec = +06d28'10".9.

    Finding chart:
    http://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/DNe/J2329/im.gif

    Light curve:
    http://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/DNe/J2329/hump.gif

    If you succeed (or have a question) in observing this target, please
e-mail to Makoto Uemura (uemura@kusastro.kyoto-u.ac.jp).

    Regarding general CCD time-series photometry, our WZ Sge page would be
helpful:

    http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/DNe/wzsge01.html

Regards,
Taichi Kato
On behalf of the VSNET Collaboration team

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  VSNET (Variable Star Network) is an international variable star observing
network, covering various areas of novae, supernovae, cataclysmic variables
(CVs), X-ray transients, and other classical eruptive, pulsating, and
eclipsing variables.  VSNET is one of invited contributing organizations
to the SkyPub AstroAlert system.

       VSNET Home Page: http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/

CCD observations of such targets are a relatively easy task for a 20-40cm
telescope; simply take as many CCD frames (with exposure times 10-30 sec)
as possible, spanning several hours per night.  The only requirements are
the weather and your patience!  If you need more help on the observing
technique, please feel free to ask on the vsnet-campaign list.

   We would sincerely appreciate volunteers who would join the VSNET
Collaboration team to study the wonders of these exotic variable stars.
To join the VSNET campaign collaborative list, send an e-mail to

         vsnet-adm@kusastro.kyoto-u.ac.jp (VSNET administrator)

with a line "SUBSCRIBE vsnet-campaign." or your comment to join the
collaboration team.

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