[vsnet-obs 4529] CVC 116 (DX And, EG Cnc, FX Cep, QY Per)

[Tonny Vanmunster <tvanmuns@innet.be>]

BELGIAN ASTRONOMICAL SOCIETY V.V.S. -  Working Group Variable Stars
Cataclysmic Variables Circular No.116             1996, December 10
Ed.: T. Vanmunster, Walhostraat 1A, 3401 Landen, BELGIUM
     Internet: tvanmuns@innet.be                  TEL. 32-11-831504
===================================================================

DX And [UG, 10.9p - 16.4p]
==========================

We have been informed by the AAVSO (through AAVSO  News  Flash  83)
about a possible outburst of this long-period dwarf nova, which  is 
on the TA/BAAVSS Recurrent Objects Programme. A confirmative obser-
vation has been reported by R. Modic on VSNET :

1996 Dec 08.223 UT,  14.9  (R. Modic, 0.50-m refl., seq: VSNET);
     Dec 09.042 UT,  13.8  (J. Griese);
     Dec 09.157 UT,  13.8  (J. Griese);
     Dec 10.101 UT,  13.9  (R. Modic);
     
The previous outburst of DX And was reported on February 29, 1996 by
L. Jensen, Denmark [CVC 84].

In an interesting note on VSNET, Taichi Kato, Kyoto University, Japan 
remarks : "The present early detection, if confirmed, of an outburst 
of DX And might provide another ... excellent opportunity in probing 
the accretion disks in dwarf novae having long orbital periods, whose 
outbursts seem to start from the inner part of accretion disks.  
GK Per and CH UMa all showed a "plateau" before reaching maximum light, 
during which the heating wave seems to propagate through the accretion 
disk inside-out. Follow-up (multicolor and time-resolved) observations 
are recommended at this moment of the event." 

Spectroscopic and photometric observations of DX And, as well as its
physical parameters, are discussed in length in (Drew, J.E. et al., 
1993, MNRAS, 260, 803-818).


EG Cnc [NL/UG:, 11.9v - 17:v]
=============================

The EG Cnc outburst, announced in our previous CVC issue, has 
received wide coverage, both from amateur and professional astro-
nomers, and so far has already resulted in extremely interesting 
photometric results. The light curve below is a compilation of
observations received from observers world-wide.

-------------------------------------------
DATE (UT)       MAGN   MS OBSERVER   
-------------------------------------------
1996 11 21.082  [15.2  mv  Poyner
1996 11 21.23   [13.7  mv  Schmeer
1996 11 30.917   12.5  mv  Schmeer
1996 11 30.951   12.0  mv  Schmeer
1996 11 30.989   11.8  mv  Schmeer
1996 12 01.021   12.1  mv  Vanmunster
1996 12 01.130   11.7  mv  Schmeer
1996 12 01.248   11.7  mv  Schmeer
1996 12 01.804   11.6  mv  Watanabe
1996 12 02.038   12.5  mv  Poyner
1996 12 02.298   12.0  mv  Hanson
1996 12 02.333   11.4: mv  Burrows
1996 12 02.710   12.44 CV  Kiyota
1996 12 02.819   11.8  mv  Watanabe
1996 12 02.992   11.8  mv  Schmeer
1996 12 03.282   11.8  mv  Dillon
1996 12 03.737   12.1  mv  Watanabe
1996 12 03.837   11.8  mv  Makiguchi
1996 12 04.008   11.9  mv  Worraker
1996 12 04.060   11.9  mv  Worraker
1996 12 04.949   12.0  mv  Worraker
1996 12 04.979   12.7  mv  Poyner
1996 12 05.023   12.0  mv  Brincat
1996 12 05.972   12.8  mv  Schmeer
1996 12 06.072   12.8  mv  Schmeer
1996 12 06.154   12.8  mv  Schmeer
1996 12 06.760   12.5  mv  Watanabe
1996 12 07.00    12.5  mv  Pietz
1996 12 07.630   12.4  mv  Watanabe
1996 12 07.738   12.47 CV  Ouda
1996 12 07.831   12.3  mv  Watanabe
1996 12 07.839   12.5  mv  Itoh
1996 12 07.93    12.4  mv  Pietz
1996 12 08.795   12.53 CV  Ouda


Various groups and observatories attempted V-band and unfiltered CCD
photometry during almost every phase of the EG Cnc outburst. Although
the eruption is still ungoing, we'd like to present a first summary
of some of the most exciting results received so far.

The first time-series photometry data were reported by Katsura Matsu-
moto of Osaka Kyoiku University, Japan, on December 4th, 1996 through
VSNET : "We obtained a continuous (four hours) CCD V-band light curve 
of EG Cnc last night. The observed light curve shows superhumps with a 
low amplitude, approximately between 0.03 and 0.04 magnitude. A preli-
minary analysis yielded a period of 0.058 day, which is one of the 
shortest known among dwarf novae."

A very comprehensive set of multi-longitude photometry data were col-
lected by the CBA network (Joe Patterson, Jonathan Kemp, Dave Harvey,
Tonny Vanmunster, Dave Skillman and S. Kiyota) : "We have obtained 
time-series photometry of EG Cnc on each night (December 1-5) since 
Schmeer's exciting recovery of the star after its 19-year slumber.  
We used data from four stations of the Center for Backyard Astrophysics 
(CBA), and added brief coverage from the Cerro Tololo 1-m telescope.  
The star continues a linear decline at 0.12 mag/night, and was at 
V=12.83 on December 5.3 UT.  During December 1-3, the star showed a 
periodic modulation at 0.0572+-0.0002 d, with ever-decreasing amplitude 
(averaging 0.03 mag peak-to-trough).  On December 4-5, the signal 
weakened further and disappeared into the noise."

After this weakening of the superhumps, a gradual recovery was obser-
ved starting from December 5/6, 1996. In a communication by Joe
Patterson, CBA New York, we read : "During a CBA-Maryland run of six 
hours centered on December 5.35 UT, the waves were at 0.027 mag and 
slightly growing.  A Cerro Tololo observation on December 6.3 showed 
that the amplitude had grown to 0.13 mag (at V=13.0), and on December 
7.3 it had grown further to 0.18 mag while the star had brightened to 
V=12.5.  The period was probably 0.0606+-0.0002 d, with a chance of 
really being 0.0645 d, the one-day alias."

This amplitude growing and period analysis was shortly afterwards
confirmed by the Ouda team of Kyoto University, Japan : "We have 
carried out time-resolved photometry of EG Cnc from Dec. 7.68 to 7.81 
at Ouda Station using a 60-cm reflector + CCD + Johnson V filter.  
A preliminary analysis using PDM method gives 0.061 (+- 0.001) d as
the best estimated period ...  Superhumps have grown to 0.20 mag."

Further superhump period determinations were reported by Allen
Shafter, Scott Dahm and Hye-kyung Lee (CBA communication), and based
on observations obtained on Dec 7 and Dec 8, 1996. They derived a
superhump period of 0.0604 (+- 0.0001) days and a full amplitude of
approx. 0.13 mag.


FX Cep [UGSS?, 15.0p - 17.5p]
=============================

The FX Cep outburst, reported in CVC 114, has received little
attention, mainly due to bad weather circumstances throughout most
of Europe and all the excitement around EG Cnc.

Observations received until now :

1996 Nov. 29.993 UT, [14.2 (G. Poyner, 0.40-m refl., seq: GSC);
     Nov. 30.814 UT,  14.5 (E. Broens, 0.35-m refl., seq: GSC);
     Nov. 30.930 UT,  14.9 (T. Vanmunster, 0.25-m SCT + ST-7 unfilt.);
     Dec. 01.781 UT,  14.6 (G. Poyner);
     Dec. 02.810 UT,  14.6 (G. Poyner);
     Dec. 04.839 UT, [14.5 (G. Poyner);

Given the very few observations, the uncertainty about the dwarf
nova subtype remains.


QY Per [UG, 14.2p - <20p]
=========================

Jochen Pietz, Germany reports an outburst of this poorly studied 
cataclysmic variable, which is included in the Belgian CVAP (Cata-
clysmic Variables Alert Programme). Although confirmative observations
are still lacking at present, we include the reported outburst in
this CVC in order to raise interest in this dwarf nova. We strongly
recommend follow-up observations, since virtually nothing is known
about QY Per. We have requested time-series photometry data from
some astronomers already, but would like to involve more observatories 
in our present quest for data.

The observation by J. Pietz :

1996 Dec 07.88 UT,  14.3  (J. Pietz);


The previous outburst of QY Per (the second one ever observed
visually) was reported on August 21, 1995 by T. Vanmunster, Belgium
[CVC 54] and further discussed in CVC 55. It turned out to be a
short outburst.


Tonny Vanmunster

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp