[vsnet-alert 4589] Re: AB Nor unusual outburst (superoutburst?)

["William S G Walker" <astroman@voyager.co.nz>]

Greetings,

The rebrightening of AB Nor looks very much like some of the delayed
superoutbursts of other stars with the precursor falling to a very low
level before triggering the main outburst.

In rather difficult conditions (4% SD) on April 8 I managed a run of 2.8
hours and measured one definite superhump with an amplitude of 0.4
magnitudes. Maximum was at Apr 08.55 and the period looked about 2 hours,
perhaps as much as 2.2 hours. But very uncertain in the absence of a second
peak.

Regards,
Stan

----------
> From: Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>
> To: vsnet-alert@kusastro.kyoto-u.ac.jp
> Subject: [vsnet-alert 4574] AB Nor unusual outburst (superoutburst?)
> Date: Thursday, April 06, 2000 7:27 PM
> 
> 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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