[vsnet-alert 671] CVC 122

[Tonny Vanmunster <tvanmuns@innet.be>]

BELGIAN ASTRONOMICAL SOCIETY V.V.S. -  Working Group Variable Stars
Cataclysmic Variables Circular No.122              1997, January 09
Ed.: T. Vanmunster, Walhostraat 1A, 3401 Landen, BELGIUM
     Internet: tvanmuns@innet.be                  TEL. 32-11-831504
     CBA Belgium Web Page : http://vsnet.astro.columbia.edu/~cba/be
===================================================================

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

Gene Hanson, Arizona, USA reports his detection of an outburst
of this interesting dwarf nova (possible SU UMa type). Tonny
Vanmunster, CBA Belgium has confirmed the outburst, using a
25-cm f/6.3 telescope and ST-7 (unfiltered) CCD. Available
observations :

1997 Jan 08.213 UT, [14.1  (G. Hanson, seq: AAVSO);
     Jan 09.194 UT,  14.4: (G. Hanson);
     Jan 09.202 UT,  14.2  (G. Hanson);
     Jan 09.560 UT,  11.6  (G. Hanson);
     Jan 09.791 UT,  11.9  (T. Vanmunster, unfiltered CCD image);


The previous outburst of BZ UMa was observed by T. Burrows, USA
on May 14, 1996 [CVC 94] at mag. 13.7 (brightening to mag. 11.9
in 2.7 hours). It was a normal outburst, that lasted for 4 days
only [CVC 96], reaching a maximum magnitude of 10.6.
     
In a recent publication, 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 if the present outburst is a superoutburst, it should be
searched for superhumps. Close photometric monitoring is of utmost
importance !

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



EG Cnc [UGWZ, 11.9v - 17:v]
===========================

Further observations of this object are given below. Please
continue your monitoring actions, as EG Cnc has sufficiently
proven to be quite 'unpredictable'.

-------------------------------------------
DATE (UT)       MAGN   MS  OBSERVER   
-------------------------------------------
1996 12 19.975  <14.0  mv  Jensen
1997 01 03.999   15.70 CU  Jensen
1997 01 04.476   13.35 CV  Ouda
1997 01 04.871   13.52 CV  Ouda
1997 01 05.04    14.1  mv  Kinnunen
1997 01 05.906   14.7  CU  Vanmunster
1997 01 05.95    15.5  mv  Kinnunen
1997 01 06.168  <14.1  mv  Shaw
1997 01 06.648  <14.8  mv  Itoh
1997 01 07.135   16.04 CU  Kiyota
1997 01 07.15   <14.1  mv  Kinnunen
1997 01 07.228  <14.6  mv  Shaw
1997 01 07.532  <14.3  mv  Takahashi
1997 01 07.89   <15.6  mv  Kinnunen
1997 01 08.219  <14.1  mv  Hanson
1997 01 08.616  <14.8  mv  Itoh
1997 01 09.193  <14.1  mv  Hanson


Tonny Vanmunster

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