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[vsnet-obs 3164] CVC 101 (WX Cet, DM Lyr, Var25 Oph, V630 Cyg)
- Date: Thu, 18 Jul 1996 21:58:04 -0100
- To: observations@aavso.org, JBortle@AOL.com, guy@tahq.demon.co.uk, tkato@kusastro.kyoto-u.ac.jp, gp@star.sr.bham.ac.uk, pvancaut@innet.be, bill.worraker@aea.orgn.uk, nogami@kusastro.kyoto-u.ac.jp, safnet@mesiob.obspm.fr, KFA02524@niftyserve.or.jp, vsnet-obs@kusastro.kyoto-u.ac.jp, NAH01147@niftyserve.or.jp, ebroens@innet.be, fidusz@alba.zpok.hu, sno@iris.elte.hu
- From: Tonny Vanmunster <tvanmuns@innet.be>
- Subject: [vsnet-obs 3164] CVC 101 (WX Cet, DM Lyr, Var25 Oph, V630 Cyg)
- Sender: owner-vsnet-obs@kusastro.kyoto-u.ac.jp
BELGIAN ASTRONOMICAL SOCIETY V.V.S. - Working Group Variable Stars
Cataclysmic Variables Circular No.101 1996, July 18
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
===================================================================
WX Cet [UGWZ, 9.5v - 17.5v]
===========================
Berto Monard, Pretoria, South Africa and Albert Jones, New Zealand
report their (independent) discovery of a superoutburst of this most
interesting UGWZ-type dwarf nova. WX Cet is part of the TA/BAAVSS
Recurrent Objects Programme and included in Steve Howell's list of
TOADs. Available observations :
1996 Jul 17.080 UT, [11.9 (P. Schmeer, 0.20-m SCT, Germany);
Jul 17.646 UT, 12.0 (A. Jones, New Zealand);
Jul 17.656 UT, 11.8 (A. Jones);
Jul 17.684 UT, 11.8 (A. Jones);
Jul 17.731 UT, 11.6 (A. Jones);
Jul 18.078 UT, 11.6 (P. Schmeer);
Jul 18.087 UT, 12.0 (B. Monard, South Africa);
Jul 18.129 UT, 12.0 (B. Monard);
Taichi Kato, Kyoto University, Japan remarks in a VSNET message :
"Maximal magnitudes of superoutbursts of WX Cet tend to have a large
scatter (~3 mag) as compared to other 'usual' SU UMa-type dwarf novae
(e.g. T. Kato, IBVS No. 4256). From this point, the present magnitude
already suggests a superoutburst. Since strong aliasing of previous
superhump observations has not yet completely solved the superhump
nature, there remains much to be done regarding superhump photometry.
WX Cet showed another rather peculiar feature during the final fading
stage of a superoutburst. In contrast to most SU UMa-type dwarf novae
(including an extreme case of AL Com), the termination of the 1991
superoutburst was not accompanied by a rapid decline."
Joe Patterson, Dept. of Astronomy, Columbia University, USA reports :
"Photoelectric photometry on the CTIO 1-m by Jonathan Kemp and Susan
Kassin showed 0.25 mag superhumps in WX Ceti on the night of July
17/18. Thus the present outburst is very likely to be a supermaximum.
A July supermax isn't perfect, but it's still the best seasonal timing
WX Cet has ever delivered. O'Donoghue et al. (1991; MNRAS 250, 363)
struggled valiantly to find the superhump period from single-site
observations in early June 1989. Their best-fit periods were in the
range 70-80 min, an awfully interesting range! But these were based on
observations of only ~2 hr/night (because of the unfavorable location
of Cetus in June), far too brief to identify the period securely.
Thus the superhump period remains unknown. Now we can fix that. But it
probably requires a multi-longitude collaboration - because even now we
can only get 4-hour runs on the star, still uncomfortably short. We
would love to hear from other observers who are able to get superhump
timings. At magnitude 11.7 and with a full amplitude of 0.25 mag, the
project may even be feasible for very experienced visual observers."
The previous outburst of WX Cet was observed on January 21, 1994 by
Thouet, York, Overbeek a/o (max. mag. 11.7), according to the Outburst
Activity Database on Selected Cataclysmic Variables.
DM Lyr [UGSU, 13.6p - 18p]
==========================
What many observers had suggested, finally has been proven : DM Lyr
is a SU UMa type dwarf nova. Evidence by CCD observations has been
obtained independently by the Ouda Team, Kyoto University, Japan
and by Tonny Vanmunster, CBA Belgium. Included are the corresponding
messages on VSNET :
"We, Ouda Team, observed DM Lyr last night (7/16) and detected
superhumps with an amplitude of about 0.1 mag. DM Lyr has, thus,
proven to be a new member of SU UMa stars! Our preliminary period
analysis gives 0.066 (+-0.002) day as the best estimated superhump
period."
"The DM Lyr CCD photometry, obtained last night (July 16/17) at the
CBA Belgium (unfiltered 90s exposures using a 25-cm SCT with ST-7 CCD)
clearly shows the existence of superhumps in this system (hence proving
the SU UMa nature). A very preliminary analysis of the superhump period
yields a best value of 0.067d +/- 0.001d (PDM method) and a mean ampli-
tude of 0.08 mag."
Photometric summary (continuation of the table in CVC 99) :
-----------------------------------------------------------------------
DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE
-----------------------------------------------------------------------
1996 07 12.506 14.13 CU Kato, Nogami VSNET
1996 07 12.617 14.6 mv Takahashi VSNET
1996 07 12.968 14.8 CU Jensen, L. VSNET
1996 07 13.026 14.4 mv TA Poyner, G. VSNET
1996 07 13.946 14.2 mv AA Vanmunster, T. VVS
1996 07 14.956 14.5 mv TA Poyner, G. VSNET
1996 07 14.971 14.4 mv Day, J. VSNET
1996 07 15.132 14.4 CU Ouimet, P. PRIV
1996 07 15.960 14.7 mv TA Poyner, G. VSNET
1996 07 15.993 14.6 mv Day, J. VSNET
1996 07 16.443 14.6 CU Kato, Baba VSNET
1996 07 16.535 [14.9 mv Takahashi VSNET
1996 07 16.87 14.4 mv Szentasko, L. VSNET
1996 07 16.967 14.6 mv TA Poyner, G. VSNET
1996 07 16.984 15.0 mv TA Worraker, B. PRIV
1996 07 17.008 15.5 CU Jensen, L. VSNET
1996 07 17.041 15.2 mv TA Worraker, B. PRIV
1996 07 17.444 14.60 CU Kato, Baba VSNET
1996 07 17.447 14.63 CU Kato, Baba VSNET
Var25 Oph [UG, 15.0 - <21.0p]
=============================
Follow-up observations of the outburst reported in CVC 100 are listed
below. Please note that Gary Poyner, UK very likely made the first
ever visual observation of this object.
-----------------------------------------------------------------------
DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE
-----------------------------------------------------------------------
1996 07 12.515 16.0 CU Iida, M. CVC 100
1996 07 13.014 [14.7 mv Poyner, G. VSNET
1996 07 13.904 16.4 CU Vanmunster, T. CVC 100
1996 07 14.946 [15.0 mv Poyner, G. VSNET
1996 07 15.914 [16.5 CU Vanmunster, T. VVS
1996 07 15.934 16.2 CU Jensen, L. VSNET
1996 07 15.949 15.7 mv Poyner, G. VSNET
1996 07 16.944 [17.8 CU Vanmunster, T. VVS
1996 07 16.959 [15.5 mv Poyner, G. VSNET
V630 Cyg [UGSU:, 13.4p - 17.2p]
===============================
The V630 Cyg outburst has remained a rather faint outburst, as indicated
by the photometric summary below. Remark that the table contains some
conflicting observations, and a brief rebrightening (unconfirmed).
-----------------------------------------------------------------------
DATE (UT) MAGN MS SEQ OBSERVER REMARKS SOURCE
-----------------------------------------------------------------------
1996 07 10.085 14.2 mv AA Broens, E. CVC 99
1996 07 10.948 [14.9 mv AA Skalak, P. PRIV
1996 07 11.039 14.4 mv Poyner, G. CVC 99
1996 07 12.534 15.6 CU Kato, Nogami VSNET
1996 07 12.581 15.3 CU Iida, M. VSNET
1996 07 12.982 15.5 CU Jensen, L. VSNET
1996 07 13.049 [14.1 mv Poyner, G. VSNET
1996 07 14.990 [15.2 mv Poyner, G. VSNET
1996 07 15.902 [16.4 CU Vanmunster, T. VVS
1996 07 15.992 14.5 mv Poyner, G. VSNET
1996 07 15.993 [14.9 mv AA Skalak, P. PRIV
1996 07 16.491 17.9 CU Kato, Baba VSNET
1996 07 16.979 [17.1 CU Jensen, L. VSNET
1996 07 17.516 18.8: CU Kato, Baba VSNET
Tonny Vanmunster