[Message Prev][Message Next][Thread Prev][Thread Next][Message Index][Thread Index]

[vsnet-obs 790] CVC 47 (GO Com, CY UMa, FN And)

BELGIAN ASTRONOMICAL SOCIETY V.V.S. -  Working Group Variable Stars
Cataclysmic Variables Circular No.47                  1995, July 21
Ed.: T. Vanmunster, Walhostraat 1A, 3401 Landen, BELGIUM
     Internet: tvanmuns@innet.be                  TEL. 32-11-831504
     P. Van Cauteren, de Borrekenslaan 54, 2630 Aartselaar, BELGIUM
     Internet: pvancaut@innet.be                  TEL. 32-3-8774098
===================================================================

GO Com [UGWZ:, 13.1p - 20p]
===========================

Tonny Vanmunster, Landen, Belgium has detected a rare outburst of  the 
dwarf  nova GO Com. Robert Fidrich, Hungary has contacted us to report
a possible confirmative observation by Robert Szabo, Hungary, using  a 
25-cm reflector. As there is still  some  uncertainty  in  the  obser-
vation of R. Szabo, additional confirmations are highly requested.

1995 Jul 16.951 UT,  13.3  (T. Vanmunster, 0.35-m refl., seq: GSC);
     Jul 18.509 UT, [13.6  (M. Moriyama, Japan, 0.33-m refl.)
     Jul 18.908 UT, [13.5  (P. Schmeer, 0.35-m refl.);
     Jul 19.86  UT,  13.2: (R. Szabo, Hungary, 0.25-m refl., seq: GSC);
     Jul 19.917 UT, [13.4  (P. Schmeer);
     Jul 19.928 UT, [13.5  (T. Vanmunster);
     Jul 20.921 UT, [13.5  (T. Vanmunster);

In IBVS 3489, T. Kato and R. Hirata describe CCD photometry of GO Com, 
and report quasi-periodic modulation with an amplitude of 0.5 mag, and 
a "periodicity" of 33 min. The same paper mentions a major outburst of 
GO Com, observed on May 30, 1989 (mv 13.2) by Watanabe  and  Kato.  As 
far  as we can deduce from our "Outburst Activity Database on Selected 
Cataclysmic  Variables",  this  constitutes the last reported positive 
observation of GO Com !

Another publication on GO Com (PASP, 102, 758-772, 1990), by S.Howell, 
P. Szkody a/o, mentions that GO Com has been seen in outburst at least 
three times. They further describe  photometric  observations  showing 
approx.  0.5  mag  flickering  on  top  of  a determined 95-min period 
(assumed to be the orbital period). The 95-min period,  although  seen 
with high confidence, may simply be flickering.

In a recent message on VSNET, T. Kato communicates: "GO Com was disco-
vered  by  Kowal as an eruptive object on a Palomar plate on 1977 July 
1.213. The variable was  confirmed  to  coincide  with  the  suspected 
variable  CSV 1959  =  SVS 382. On the other hand, Usher independently 
discovered a very blue star of B=18.1 during the survey of  the  north 
galactic pole region. This star (US 31) was identical to GO Com.  Vogt 
and  Bateson  classified  this  variable  as a WZ Sge-type dwarf nova, 
because of its large outburst amplitude and low outburst frequency. 
During  the  1989 outburst, the object attained a maximal magnitude of 
mv=13.2,  which  was followed by a rapid decline of about 1 mag in one 
day. This rapid decline suggests a normal outburst of an SU UMa star. 
Despite the seasonal gaps in monitoring this object, the  extreme  low 
outburst  frequency  of  this  dwarf nova now seems to be established. 
Apparent absence of long outbursts,  infrequent  short  outbursts  and 
possible excursion to a low state (mp ~ 20) may suggest a relationship 
to BZ UMa. Intensive observations during the present outburst,  syste-
matic  searches  for  historical  outbursts  and  determination of the 
physical parameters are recommended."

It finally is interesting to note that GO Com is classified as a  TOAD 
(Tremendous Outburst Amplitude Dwarf Nova) by S. Howell.


CY UMa [UGSU, 11.9v - 17.0v]
============================

An outburst of this SU UMa-type dwarf nova has been reported by
Tonny Vanmunster, Landen, Belgium. Subsequent confirmations have come
from Patrick Schmeer, Bischmisheim, Germany and Eric Broens, Mol,
Belgium.

1995 Jul 19.932 UT, [14.0  (T. Vanmunster, 0.35-m refl., seq: AAVSO);
     Jul 20.903 UT, [13.5  (P. Schmeer, 0.20-m SCT, seq: Fujino);
     Jul 20.913 UT,  13.9  (T. Vanmunster);
     Jul 20.922 UT,  13.5  (P. Schmeer);
     Jul 20.932 UT,  13.8  (E. Broens, 0.35-m refl., seq: AAVSO);
     Jul 20.994 UT,  13.3  (P. Schmeer);

CY UMa was last seen in outburst on May 20, 1995 (P. Schmeer and T.
Vanmunster) [CVC 37]. It was a normal (faint) outburst [CVC 40].

It's interesting to note that the present outburst and the two 
preceding ones all are separated by (almost) exactly 2 calendar months.


FN And [UG, 13.5p - 17.5p]
==========================

Tonny Vanmunster, Landen, Belgium reports another outburst detection.
FN And, last seen in outburst on December 5th, 1994 (P. Schmeer) 
[CVC 22], is bright again. Eric Broens, Mol, Belgium has confirmed the
event. Independent outburst detections have been reported by Patrick 
Schmeer, Bischmisheim, Germany and by Gary Poyner, Birmingham, UK.

1995 Jul 19.974 UT, [14.1  (T. Vanmunster, 0.35-m refl., seq: TA);
     Jul 20.951 UT,  13.3  (T. Vanmunster);
     Jul 20.963 UT,  13.4  (E. Broens, 0.35-m refl.,  seq: TA);
     Jul 21.000 UT,  13.2  (T. Vanmunster);
     Jul 21.041 UT,  13.3  (P. Schmeer, 0.20-m SCT,   seq: TA);
     Jul 21.049 UT,  13.0  (G. Poyner,  0.40-m refl., seq: TA);

During the December 1994 outburst, it reached a maximum brightness of
mag. 13.2, and remained visible for 4 nights [CVC 23].


V542 Cyg [UGSS:, 13.0p - 18.3:p]
================================

Several observers have submitted their V542 Cyg observations, yielding
a good coverage of the present outburst, which is  summarized  in  the
table below.

-----------------------------------------------------------------------
DATE (UT)       MAGN  MS SEQ  OBSERVER        REMARKS        SOURCE
------------------------------------------------------------------------
1995 07 10.053 [13.9  mv AA   Vanmunster, T.  35-cm refl.    CVC 46
1995 07 13.906 [13.5  mv AA   Vanmunster, T.  35-cm refl.    CVC 46
1995 07 14.955  13.8  mv AA   Vanmunster, T.  35-cm refl.    CVC 46
1995 07 15.181 [13.5  mv AA   Mc Kenna, J.    28-cm SCT      VSNET
1995 07 15.997  13.9  mv AA   Vanmunster, T.  35-cm refl.    CVC 46
1995 07 16.11   13.8  mv AA   Scovil, C.                     VSNET
1995 07 16.894  13.9  mv AA   Vanmunster, T.  35-cm refl.    CVC 46
1995 07 16.928 [13.5  mv AA   Jensen, L.      33-cm refl.    priv(JEN)
1995 07 16.945  13.7  mv AA   Broens, E.      35-cm refl.    CVC 46
1995 07 19.88   14.1  mv AA   Szabo, R.       25-cm refl.    priv(FID)
1995 07 19.900 [13.9  mv AA   Vanmunster, T.  35-cm refl.    VVS
1995 07 20.903 [13.9  mv AA   Vanmunster, T.  35-cm refl.    VVS


CVAP UPDATE
===========

Two extremely interesting cataclysmic variables have been added to the 
CVAP (Cataclysmic Variables Alert Programme). It concerns :

   NSV05543  position (1950.0) : R.A. = 12h16m09s
                                 Decl = +40d18.3'
             type : UG?
             mag. range : 12.0 - [14p
             No additional information available on this object

   S10932    position (J2000.0): R.A. = 12h39m32.1s
                                 Decl = +21d08'06"
             type : UG:+E
             mag. range : 13.4 - 18.5p
             This a suspected eclipsing CV, and only the third member
             of eclipsing SU UMa-type dwarf novae in the northern hemi-
             sphere. More information on S10932 is given in IBVS 4182.

Paul Van Cauteren, Aartselaar, Belgium has prepared GSC-based charts for
the two new CVAP objects. They are available from the editors upon simple
request.


Tonny Vanmunster