[vsnet-alert 806] outburst of OY Car

[Taichi Kato <tkato>]

   Following the initial alert by Michael Mattiazzo (vsnet-alert 802),
following observations have been reported to vsnet-alert and vsnet-obs.

   YYMMDD(UT)   mag  code
   970312.497  <127  MKA
   970316.433  <127  MKA
   970325.424   117  MKA
   970325.453   116  MKA
   970325.562   116  MKA
   970326.417   114  MKA
   970326.458   115  MKA
   970326.500   116  MKA
   970326.542   115  MKA
   970326.801   111  HJN

   Judging from the brightness and duration, the present outburst may well
be a superoutburst, since its last one in 1995 October - November.

   OY Car is one of the most well-known eclipsing SU UMa-type dwarf novae,
which have been and will be teaching us much about the physical processes
going in superoutbursting dwarf novae.  OY Car has played an important
role in this field [1,2,3].

[1] J. H. Wood et al., 1989, ApJ 341, 974
[2] F. V. Hessman et al., 1992, AsAp 263, 147
    (OY Carinae: the secrets of the super-humps revealed)
[3] I. Billington et al., 1996, MNRAS, 279, 1274 and references therein

   I would also like to urge visual (and CCD, of course) observers to record
spectacular eclipses (together with possible superhumps) of this short-period
cataclysmic binary.  A good northern example may be found at
(http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/DNe/htcas.html).

   According to [1], eclipse are expected to occur:

   HJED = 2443993.553691 + 0.0631209295 E
                   +/-50          +/-20

Regards,
Taichi Kato

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