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[vsnet-campaign 858] DI UMa returning to its "RZ LMi-like" state?

DI UMa returning to its "RZ LMi-like" state?

  Recent outburst observations of DI UMa by Maciej Reszelski indicate
that detectable outbursts of DI UMa comes every 24-31 days (depending
on observation gaps).  If the detected outbursts are superoutbursts,
this observed interval is pretty close to the 22-d value (Kato et al.
1996, PASJ 48, 93L; see also vsnet-alert 374).  If this is confirmed,
the system may have returned to the state originally qualified DI UMa
as the "most extremely RZ LMi-like object" (the extreme end of ER UMa
stars).   This indication may be emerging in 1999 (vsnet-alert 3841).
Further observations, even nightly snapshot CCD photometry, are highly
welcomed.  DI UMa has a superhump period of 0.0555 d, one of the shortest
known among all SU UMa-type systems.  Time-series photometry during
outburst(s) is also very helpful in studying the nature of the outburst.

  DI UMa is located at 09h 12m 16s.08, +50o 53' 54".8 (J2000.0).

  YYYYMMDD(UT)   mag  observer
  20010216.001  <155  (M. Reszelski)
  20010218.999   157: (M. Reszelski)
  20010222.983   156  (M. Reszelski)
  20010224.008   157: (M. Reszelski)
  20010225.065   158: (M. Reszelski)
  20010227.926  <155  (M. Reszelski)
  20010301.978  <155  (M. Reszelski)
  20010303.015  <148  (M. Reszelski)
  20010313.892  <155  (M. Reszelski)
  20010315.974  <155  (M. Reszelski)
  20010316.937  <155  (M. Reszelski)
  20010320.953  <155  (M. Reszelski)
  20010321.932   156: (M. Reszelski)
  20010326.906  <155  (M. Reszelski)
  20010327.864  <155  (M. Reszelski)
  20010328.881  <155  (M. Reszelski)
  20010331.931  <153  (G. Poyner)
  20010404.931  <153  (G. Poyner)
  20010410.849  <155  (T. Kinnunen)
  20010412.921  <155  (M. Reszelski)
  20010414.912   160: (M. Reszelski)

On-line references on VSNET:

  [vsnet-alert 374]
  http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-alert/msg00374.html

  [ER UMa stars]
  http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/DNe/eruma.html

Regards,
VSNET Collaboration team

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