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[vsnet-campaign-news 3] News from VSNET No. 3
*** News from VSNET ***
VSNET (Variable Star Network) is an international variable star observing
network, covering various areas of novae, supernovae, cataclysmic variables
(CVs), X-ray transients, and other classical eruptive, pulsating, and
eclipsing variables. VSNET is one of invited contributing organizations
to the SkyPub AstroAlert system.
The "News from VSNET", mainly focusing on recent remarkable activities of
CVs and related systems, is issued on a weekly basis, except on occasions
of extremely urgent or transient events.
Please refer to the VSNET Home Page for more details of events and
objects listed.
VSNET Home Page: http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/
VSNET provides a number of mailing lists, on which various news and topics
are discussed. Subscriptions to the VSNET mailing lists are free of charge;
please refer to the instruction on the above page if a reader needs more
information of the list structure.
Regards,
Taichi Kato
On behalf of the VSNET administrator team
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The following was issued on May 29, 2000, as VSNET campaign circulation 143.
XTE J1118+480 is the unusual X-ray nova in Ursa Major (IAUC 7389),
whose optical counterpart was discovered by the VSNET team and announced
as vsnet-alert 4503 and IAUC 7390. The object is now slowly fading at
around mag 13.0, with hump features which could be attributed to growing
superhumps. The VSNET Collaboration page on the WWW has been updated
(please refer to the URL below).
Several other interesting dwarf novae are reported in outburst, and
followed by a number of observers. For southern observers, the rare outburst
of BD Pav (formerly considered as a nova) would provide an excellent
opportunity to catch it in the outbursting state. The object is known as
a shallow eclipser; detailed CCD observation of eclipses would prove the
structure of the accretion disk in this system. HS Vir is a superoutbursting
target suitable for observation from both hemispheres. The system is bright
enough to be caught by a small telescope with a CCD.
We would sincerely appreciate volunteers who would join the VSNET
Collaboration team to study the wonders of these exotic variable stars.
To join the VSNET campaign collaborative list, send an e-mail to
vsnet-adm@kusastro.kyoto-u.ac.jp (VSNET administrator)
with a line "SUBSCRIBE vsnet-campaign."
(VSNET campaign members are strongly recommended to subscribe to vsnet-alert
at the same time).
Other current topics in other VSNET mailing lists include the discussion
on the nature and definition of R CrB stars, recent supernovae, etc.
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VSNET Weekly Campaign Summary
*** Last week news ***
(new targets)
HS Vir
The observation by A. Pearce on 21 May (14.2mag) indicated the outburst
of this SU UMa-type dwarf nova (vsnet-alert 4877, vsnet-campaign 121).
The last confirmed superoutburst of HS Vir occurred in 1999 May.
CCD time-resolved photometry by S. Kiyota on 24 May has confirmed the
presence of definite superhumps (vsnet-campaign 128).
The superoutburst is now ongoing. The superhump evolution should be
studied through more time-series observations.
BD Pav
A. Pearce and R. Stubbings reported the SS Cyg-type dwarf nova BD Pav
occurred one of its relatively rare outbursts. The last reported
outburst occurred in 1998 November. According to Barwig (Astron. Astrophs.
124, 287, 1983), the object is a grazing eclipser (depth 0.5 mag) with
a period of 0.1793015 d (vsnet-campaign 132).
Time-series photometry, especially in eclipses, are strongly urged.
LX Ser
The eclipsing novalike object LX Ser tends to vary in greater amplitudes
than in recent years (vsnet-campaign 141). This may be a signature of
weak dwarf nova-type activity. If the current activity leads to dwarf
nova outbursts, this eclipsing system may provide a unique opportunity to
investigate the disk structure of Z Cam-type dwarf nova.
Careful and continued observations are strongly encouraged.
(continuous targets)
XTE J1118+480
The source have kept a gradual decline (~0.06mag/d) from long lasted
plateau (vsnet-campaign 116,124,138,139). On 22 May, L. Cook
reported the light curve had changed to slower rise and faster (about
half of an hour) decline, and something precessing was guessed
(vsnet-campaign 112). The data obtained by VSNET collaboration team
showed a relatively sharp humps on the sinusoidal curve (vsnet-campaign
135).
It is still in bright state although decline started. Continuous
observations are encouraged.
CI Aql
T. Kato reported the brightening trend during the general decline
was interrupted by the rapid, almost linear, fading by ~0.1 mag within
2+ hours on May 23 (vsnet-campaign 118). Other than the general trend,
intra-night variation is likely present (vsnet-campaign 125). In the
light curve obtained by S. Kiyota on May 24, the object showed a fading
of ~0.1 mag around the predicted secondary eclipse (vsnet-campaign 127).
His observation on May 25 also confirmed the presence of short-term
variability, whose characteristics seem to be different from that
reported in early post-maximum stage (vsnet-campaign 129).
The whole profiles of both the primary and secondary eclipse are
poorly unknown yet.
V359 Cen
A fading rate from outburst is comparable to the superoutburst
fading (vsnet-campaign 119). It is confirmed that the linear fading
continued till 25 May.
The current state should be confirmed.
KK Tel
The long outburst of KK Tel (suspected SU UMa-star) started a rapid
fading on 26 May (vsnet-campaign 133). The duration of the outburst
exceeds 8 d, but the decline rate may look a little slower than that
of typical SU UMa-type superoutburst.
RX J0640-24
The presumable superoutburst of RX J0640-24 has entered the rapid
decline stage on 24 May (vsnet-campaign 131). The rate of decline,
the duration of the plateau phase, the rate of rapid decline are all
characteristic to those of superoutbursts. Now it is in quiescence.
RX J1450.5+6403
T. Vanmunster reported that this newly discovered SU UMa-type dwarf
nova entered the rapid decline phase after first detected superoutburst
(vsnet-alert 4885). He has collected a total of over 5000 observations
at 4 CBA stations.
The potential re-brightening should be checked.
*** General information ***
RX J0640-24
The light curve obtained by W. Walker on May 19 can be seen in
[vsnet-campaign 114]
HS Vir
Previous preprints are available at:
http://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/preprints/HS_Vir
and http://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/preprints/HS_Vir-2
XTE J1118+480
The light curves obtained by VSNET collaboration team can be seen at:
http://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/Xray/XTEJ1118/jd30-90lc.gif
and http://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/Xray/XTEJ1118/jd60-90ph.gif
or http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Xray/xtej1118-camp.html
BD Pav
eclipse ephemeris: see [vsnet-campaign 140]
(This summary is reproduction free.)
Regards,
Makoto Uemura
vsnet-adm@kusastro.kyoto-u.ac.jp
Return to Daisaku Nogami
vsnet-adm@kusastro.kyoto-u.ac.jp
VSNET Home Page