[vsnet-alert 855] CVC 135 (S10932, AK Cnc)

[Tonny Vanmunster <tvanmuns@innet.be>]

BELGIAN ASTRONOMICAL SOCIETY V.V.S. -  Working Group Variable Stars
Cataclysmic Variables Circular No.135                1997, April 23
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
===================================================================

S10932 [UG:+E, 13.4 - 18.5p]
============================

Tonny Vanmunster, CBA Belgium reports an outburst detection of
this eclipsing dwarf nova, which is part of the Belgian CVAP.
Visual confirmation has been obtained from Gary Poyner, UK.
The observations are :

1997 Apr 23.889 UT,  14.1  (T. Vanmunster, unfilt. CCD, 0.25-m SCT);
     Apr 23.909 UT,  13.5  (G. Poyner, 0.40-m refl.);


According to our data in the Outburst Activity Database on Selected
Cataclysmic Variables, the object was last seen in outburst on 
March 26, 1996 by M. Iida (CCD detection) at mag 14.6 [CVC 90].
It was a short and very faint outburst.


S10932 is located at R.A. = 12h39m32.1s, Decl.= +21d08'06" (J2000.0). 
One of the few references in professional literature on S10932 is 
IBVS 4182, in which Wenzel and Schwartz describe the object as a new 
eclipsing cataclysmic variable (likely a dwarf nova) below the period 
gap. Remark that this positions S10932 amongst the few known eclipsing 
dwarf novae in the northern hemisphere. 

CVC 78 reports eclipse observations by the Taichi Kato and the Ouda 
team, Kyoto University, Japan. They observed eclipses as deep as 3.2 
mag. in V, which is one of the deepest known eclipse amplitudes among 
outbursting dwarf novae. Kato further measured the duration of 
eclipses and found a value of nearly 10 minutes. Similar deep eclipses 
were also reported by German astronomers Peter Kroll and Gerold Richter 
of Sonneberg Observatory, who measured an amplitude of about 4.4 mag 
(R band).

An analysis by P. Kroll and G. Richter of CCD mid-eclipse observations 
of S10932 made at Sonneberg Observatory with a 60-cm-Cassegrain telescope 
from 1994, May 11 to 1996, Jan 04, and combined with observations 
reported by the Ouda team, yielded following mid-eclipse ephemerides :
Min (HJD) = J.D. 2449486.48166 + 0.0870386727 * E".


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

Gary Poyner, UK reports his visual detection of an outburst of
this UGSU-type dwarf nova, which is on the "Recurrent Objects 
Programme" of the TA/BAAVSS. Tonny Vanmunster, CBA Belgium has
confirmed the observation by CCD. Available estimates :

1997 Apr 23.882 UT,  13.2  (G. Poyner, 0.40-m refl., seq: TA);
     Apr 23.914 UT,  13.1  (T. Vanmunster, unfilt. CCD, 0.25-m SCT);
     Apr 23.914 UT,  13.2  (G. Poyner);


AK Cnc was last seen in outburst on May 4, 1996 by T. Burrows, USA
and B. Worraker, UK at mag 13.4 [CVC 93]. An unconfirmed outburst
observation was furthermore reported on November 23, 1996 by
B. Worraker, at mag. 14.2.

In an A&A paper on the March 1995 superoutburst of AK Cnc, R.E. 
Mennickent et al. report superhump observations with an amplitude of 
0.2 mag (which appeared 4 days after maximum) and a period of 
0.06749 d. From this result, they derived a likely orbital period of 
0.065 d, a mass ratio (M2/M1) of 0.21 and a distance of 325 parsecs. 
They furthermore report an average cyclelength of 47 days.


Tonny Vanmunster

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