[vsnet-alert 2762] Re: AAVSO News Flash - No. 405

[Patrick Schmeer <extpasc@rz.uni-sb.de>]

>
>
>              THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS
>                   25 Birch Street, Cambridge, MA 02138 USA
>                   Tel. 617-354-0484       Fax 617-354-0665
>                            http://vsnet.aavso.org
>
>                        * * *  AAVSO NEWS FLASH  * * *
>
>Subject: 0640-16  HL CMA        0846+58  BZ UMA           No. 405
>         0741-12  UY PUP        0854-24  VZ PYX           March 10, 1999
>
>----------------------------------------------------------------------------
>----------------------------------------------------------------------------
>...
>
>0846+58  BZ URSAE MAJORIS
>
>The outburst of BZ UMa that was reported in News Flash No. 404 appears to
>be a superoutburst, as indicated by the following observations:
>
>                     AAVSO Observer                           AAVSO Observer
>    UT        Mag.     Initials              UT        Mag.     Initials
>
>MAR 06.1465   15.9:      HSG             MAR 09.788    10.4       MUY
>MAR 07.1326  <15.7       HSG             MAR 10.1042   10.8:      HSG
>MAR 08.944    14.1       OJR             MAR 10.1410   10.8:      HSG
>
>We encourage observers to monitor this star and report their observations to
>the AAVSO, with timings carried to 4 decimal places. It is recommended to
>observe this reported superoutburst of BZ UMa every 5 minutes for at least 3
>to 4 hours in search of superhumps. According to the AAVSO International
>Database, the last recorded superoutburt of BZ UMa was on April 7, 1998 when
>the star reached magnitude 10.9 at maximum.


That's complete nonsense. The 1998 April outburst was clearly a short one. And 
the latest estimates by Gary Poyner and myself seem to indicate that BZ UMa is
currently about 1.5 magnitudes fainter than 1.0 days ago. A bright outburst of
a (suspected) SU UMa-type dwarf nova doesn't necessarily mean a supermaximum. 
The only distinction between normal outbursts and superoutbursts is their      
duration. If a SU UMa-type dwarf nova is near maximum for the third consecutive
night then you can (rather) safely assume that it's a supermaximum.  
 
Regards,
Patrick

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