[vsnet-campaign 272] V844 Her (super?)outburst prediction

[Taichi Kato <tkato>]

V844 Her (super?)outburst prediction

   As predicted by T. Watanabe-san in [vsnet-future 12], the next outburst
of the unique SU UMa-type dwarf nova V844 Her is predicted to occur within
two weeks!  Because of its best seasonal visibility, we should put this
target on the potential campaign list.  If the superoutburst occurs as
predicted, this present observation would provide unique information just
preceding the superoutburst (rarely obtained!).

   The importance of the object can be seen at the page:

   http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/DNe/v844her.html

   And from our article in IBVS 4902:
  (or http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet/msg02010.html
   in the preprint form).

   Aside from V485 Cen, almost all of SU UMa-type dwarf novae with the
shortest superhump (orbital) periods belong either to what is called
WZ Sge-type dwarf novae (Bailey 1979; Downes, Margon 1981; O'Donoghue
et al. 1991) and ER UMa-type dwarf novae (for a review, see Kato et al.
1999).  The former category contains WZ Sge, AL Com, HV Vir, EG Cnc,
and related members LL And, SW UMa, WX Cet and T Leo.  The latter group
contains DI UMa and RZ LMi.  From available photometric materials
(Antipin (1996) and observations to VSNET), long and bright outbursts
(presumably superoutbursts) are separated by 220--290 d, without yet
detectable normal outbursts.  Such a low frequency of normal outbursts
resembles that of SW UMa, another SU UMa-type dwarf nova with a short
orbital period, but the relatively regular occurrence of superoutbursts
in V844 Her makes a slight difference.  It may be that V844 Her occupies
a previously unknown extension of WZ Sge-type dwarf novae toward
the short recurrence period.

Regards,
Taichi Kato
VSNET Collaboration team

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