[vsnet-obs 2776] CVC 94 (BZ UMa, V632 Cyg, AK Cnc, V1316 Cyg)

[Tonny Vanmunster <tvanmuns@innet.be>]

BELGIAN ASTRONOMICAL SOCIETY V.V.S. -  Working Group Variable Stars
Cataclysmic Variables Circular No.94                   1996, May 14
Ed.: T. Vanmunster, Walhostraat 1A, 3401 Landen, BELGIUM
     Internet: tvanmuns@innet.be                  TEL. 32-11-831504
     --------------------------------------------------------------
         The CATACLYSMIC VARIABLES Home Page: http://vsnet.cv.psi.edu
===================================================================

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

We have been informed by Janet Mattei, AAVSO, through AAVSO News
Flash 21, about an outburst of this most interesting UGSU-type dwarf
nova.

1996 May 13.207 UT, [13.7  (T. Burrows, USA, AAVSO NF 21);
     May 14.006 UT, [13.7  (G. Poyner, UK, 0.40-m refl.);
     May 14.194 UT, [14.5  (G. Hanson, USA, AAVSO NF 21);
     May 14.215 UT,  13.7  (T. Burrows);
     May 14.271 UT,  12.6  (T. Burrows);   
     May 14.306 UT,  12.3  (T. Burrows);     
     May 14.326 UT,  11.9  (T. Burrows);       


The last outburst of BZ UMa recorded in the Outburst Activity Database 
was on June 14, 1995 (G. Poyner) [CVC 41]. This was a normal outburst,
during which BZ UMa reached maximum magnitude 11.5 [CVC 43].

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]. The
object further appears in the list of known TOADs, issued by Howell [3].

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.
[3] Howell, S., 1995, AJ, 439, 337-345



V632 Cyg [UGSS, 12.6p - 17.5p]
==============================

Gary Poyner, Birmingham, UK reports an outburst of this TA/BAAVSS
Recurrent Objects Program target, which has been confirmed on CCD
by L. Jensen, Center for Backyard Astrophysics CBA Denmark. The
available observations are :

1996 May 06.075 UT, [15.7  (T. Vanmunster, Belgium, 0.25-m SCT + CCD);
     May 07.055 UT, [14.6  (G. Poyner, UK, 0.40-m refl.);
     May 13.052 UT,  13.9  (G. Poyner);
     May 14.065 UT,  14.2  (G. Poyner);


Data in the Outburst Activity Database indicate that this object was
last seen in outburst on October 25, 1995 (J. Pietz, Germany and
M. Moriyama, Japan) [CVC 66]. It reached mag 14.0 during that outburst.



AK Cnc [UGSU, 13p - <17p]
=========================

We received following observations in addition to the ones already
mentioned in CVC 93 :

1996 May 07.906 UT, [13.6   (L. Jensen, Denmark, 0.35-m refl.);
     May 07.910 UT,  13.5   (G. Poyner, UK, 0.40-m refl.);
     May 09.479 UT,  14.25V (S. Kiyota, Japan, ST-6 CCD + Optec V filter);



V1316 Cyg [UGSU:, 14.5p - <17.5p]
=================================

Following the outburst announcement in CVC 92, only very few addi-
tional observations have been received. The object thus remains 
almost unstudied, as far as we know.

1996 Apr. 30.998 UT,  14.2  (L. Jensen, Denmark, 0.25-m SCT + CCD);
     May  05.024 UT, [14.8  (G. Poyner, UK, 0.40-m refl.);
     May  08.010 UT, [14.8  (G. Poyner);



CORRECTION TO CVC 93
====================

The observations of SW UMa by R. Novak were made at Copernicus
Observatory, Brno, Czech Republic (not Hungary). We apologize for 
any inconvenience.


Tonny Vanmunster

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