[vsnet-alert 4574] AB Nor unusual outburst (superoutburst?)

[Taichi Kato <tkato>]

AB Nor unusual outburst (superoutburst?)

  Followed by the report by Andrew Pearce on the rare outburst on Apr. 1,
Rod Stubbings reports a remarkable rebrightening on Apr. 6.  The low
outburst frequency, the large outburst amplitude and the unusual development
of outburst suggest that AB Nor is an excellent candidate of an SU UMa-type
dwarf nova, currently likely undergoing a superoutburst.  Time-resolved
CCD photometry is very strongly encouraged.  Although Downes et al. listed
a revised astrometry of the object, the lack of a USNO counterpart at the
cataloged position apparently requires further outburst astrometry.
If the quiescent counterpart is fainter than mag 20, the object is now
undergoing a large-amplitude (exceeding 6 mag) outburst.

  YYYYMMDD(UT)   mag  observer
  20000325.795  <142  (A. Pearce)
  20000326.839  <148  (A. Pearce)
  20000327.804  <150  (A. Pearce)
  20000328.794  <150  (A. Pearce)
  20000329.560  <144  (R. Stubbings)
  20000329.794  <150  (A. Pearce)
  20000329.797  <150  (A. Pearce)
  20000401.788   144  (R. Stubbings)
  20000401.830   142  (A. Pearce)
  20000402.744   148  (R. Stubbings)
  20000402.806   147  (A. Pearce)
  20000403.467  <146  (R. Stubbings)
  20000405.458  <146  (R. Stubbings)
  20000406.557   140  (R. Stubbings)
  20000406.573   141  (R. Stubbings)
  20000406.579   140  (R. Stubbings)
  20000406.590   141  (R. Stubbings)
  20000406.610   140  (R. Stubbings)
  20000406.625   139  (R. Stubbings)

  For calibrating CCD photometry, the following star would be useful.
The field also contains a number of Tycho and Tycho-2 stars.

                              V                     B-V
  154917.4 -430457 (2000.0) 13.70 LONEOS ABNor4(45) 0.67 - -

  We are very looking forward to hearing successful time-series CCD photometry
reports from worldwide, and please post timely to vsnet-alert confirmatory
observations, new findings, the progess of the outburst and observations.

Regards,
Taichi Kato

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