[vsnet-obs 1418] CVC 66 (V630 Cyg, V632 Cyg)

[tvanmuns@innet.be (Tonny Vanmunster)]

BELGIAN ASTRONOMICAL SOCIETY V.V.S. -  Working Group Variable Stars
Cataclysmic Variables Circular No.66               1995, October 26
Ed.: T. Vanmunster, Walhostraat 1A, 3401 Landen, BELGIUM
     Internet: tvanmuns@innet.be                  TEL. 32-11-831504
===================================================================

V630 Cyg [UGSU:, 13.4p - 17.2p]
===============================

Eric Broens, Mol, Belgium reports (another) outburst of this CVAP object.
The previous (normal) outburst of V630 Cyg was detected as recently as
October 21st (CVC 65), after which the object faded below mag. 14.9. Given 
the very short interval between these two successive outbursts, it is very 
likely that the current outburst is a (long awaited) superoutburst. The 
phenomenon of a short outburst immediately preceding a superoutburst has been 
observed in a number of SU UMa-type dwarf nova systems (e.g., AY Lyr). These 
so called "precursor" type short outbursts are currently understood as a
trigger 
mechanism for superoutbursts, and already have been explained in the Osaki
model of thermal and tidal instabilities of the accretion disk (Osaki 1989). 

Paul Van Cauteren, Aartselaar, Belgium has confirmed the outburst using a
CCD with V-filter. Visual confirmation has been obtained by Tonny Vanmunster,
Landen, Belgium.

A first set of observations is presented below. It will be completed in a next 
circular :

1995 Oct 20.945 UT, [15.2  (E. Broens, 0.35-m refl., seq: AAVSO);
     Oct 21.763 UT,  14.2  (T. Vanmunster, 0.35-m refl., seq: AAVSO);
     Oct 21.774 UT,  14.3  (E. Broens); 
     Oct 22.779 UT, [14.9  (T. Vanmunster);
     Oct 23.883 UT, [14.9  (T. Vanmunster);
     Oct 24.606 UT, [14.5  (M. Moriyama, 0.33-m refl.);
     Oct 25.610 UT, [14.5  (M. Moriyama);
     Oct 25.815 UT,  14.0  (E. Broens);
     Oct 25.854 UT,  14.9: (P. Van Cauteren, 0.40-m refl.+CCD+V-filter);
     Oct 25.932 UT,  14.6  (T. Vanmunster);

Needless to stress that it is of great importance to monitor the present 
outburst and to look for the development of superhumps. We strongly encourage
professional astronomers to keep us informed about their findings.


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

Eric Broens also reports an outburst detection of V632 Cyg, an object
belonging to the Recurrent Objects Programme of The Astronomer/BAA. His
observation confirms the possible sightings by M. Moriyama, Sasebo, Naga-
saki, Japan (mentioned on VSNET). Additional confirmations were received
from Paul Van Cauteren (using a CCD with V-filter) and Tonny Vanmunster.

1995 Oct 23.882 UT, [15.3  (T. Vanmunster, 0.35-m refl., seq: AAVSO);
     Oct 24.603 UT,  14.7: (M. Moriyama, 0.33-m refl.);
     Oct 25.609 UT,  14.6: (M. Moriyama, 0.33-m refl.);
     Oct 25.812 UT,  14.2  (E. Broens, 0.35-m refl., seq: AAVSO);
     Oct 25.852 UT,  14.8: (P. Van Cauteren, 0.40-m refl+CCD+V-filter);
     Oct 25.933 UT,  14.0  (T. Vanmunster);

V632 Cyg was last reported in outburst by Laszlo Szentasko on March 2, 1995
(CVC 30), and attained a maximum brightness of mag. 12.9. It remained visible
for more than one week (CVC 32).


Tonny Vanmunster

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