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[vsolj-alert 73] Rare outburst of BZ UMa



Rare outburst of BZ UMa

 今度はSU UMa型が提唱されながらスーパーアウトバーストのつからないBZ UMaの
 まれなアウトバーストの報告です。今晩は観測できる条件のところもあるかも
 知れませんね。

From owner-vsnet-alert@kusastro.kyoto-u.ac.jp Tue Apr  7 06:29 JST 1998
Date: Mon, 6 Apr 1998 23:23:20 +0200 (MET DST)
From: Tonny Vanmunster <tvanmuns@innet.be>
Subject: [vsnet-alert 1646] CVC 166 (BZ UMa)

BELGIAN ASTRONOMICAL SOCIETY V.V.S. -  Working Group Variable Stars
Cataclysmic Variables Circular No.166                1998, April 06
Ed.: T. Vanmunster, Walhostraat 1A, 3401 Landen, BELGIUM
     Internet: tvanmuns@innet.be                  TEL. 32-11-831504
     CVC Web Page : http://vsnet.cba.phys.columbia.edu/cvc
===================================================================

BZ UMa [UGSU:, 10.5v - 17.8v]
=============================

Eric Broens, Mol, Belgium reports the detection by Eddy Muyllaert,
Belgium of an outburst of BZ UMa. This interesting dwarf nova is
a possible SU UMa-type cataclysmic variable. Eric Broens has been
able to confirm the outburst through clouds. Available observations :

1998 Apr 05.476 UT, [15.7  (G. Hanson, 0.46-m refl.);
     Apr 06.854 UT,  12.2  (E. Muyllaert, C-11 telescope, AAVSO seq);
     Apr 06.869 UT,  12.1: (E. Broens, 0.35-m reflector, AAVSO seq);


According to our records, the previous outburst of BZ UMa was observed 
by G. Hanson, USA on January 9, 1997 [CVC 122] at mag 14.4 (brightening 
to mag. 11.6 shortly afterwards). Unfiltered time-series CCD photometry 
at the CBA Belgium Observatory during that outburst did not reveal
any superhumps [CVC 127].

Ringwald et al. [1] point out that BZ UMa has very infrequent outbursts, 
lasting 10-20 days, with large amplitudes (delta V approx. 6 mag.). He 
further notes that superhumps have eluded detection in BZ UMa, but may 
well exist. He finds an orbital period of 0.0679 days.

BZ UMa does have normal outbursts as well as superoutbursts, as can be
derived from the long-term lightcurve of BZ UMa, published in [2]. 

Given the fact that the SU UMa-type nature of BZ UMa is still unclear,
and that no superhumps have been detected so far in this system, it is
evident that close photometric monitoring by CCD is of utmost 
importance !

References
----------
[1] Ringwald, F.A., et al., 1994, MNRAS, 271, 323-342
[2] Jurcevic et al., 1994, PASP, 106, 481.



Editorial absence
+++++++++++++++++

Please note that the Editor will be absent from April 14 till 
April 18.



Tonny Vanmunster

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