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[vsnet-campaign-news 5] News from VSNET No. 5
*** 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 Jun. 6, 2000, as VSNET campaign circulation 175.
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 reported slow fading seem to have
become apparently stopped. Hump features with a changing profile has been
continuously observed. The VSNET Collaboration page on the WWW has been
updated with a new light curve and hump light curves.
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Xray/xtej1118-camp.html
Several other interesting dwarf novae are reported in outburst, and
followed by a number of observers. For southern observers, the rare long
outburst of BD Pav (formerly considered as a nova) warrants an excellent
opportunity to catch emerging eclipses as it fades. V660 Her is a relatively
recently recongnized SU UMa-type dwarf nova, now undergoing a bright (mag
about 14.0) superoutburst. CCD time-series observations are strongly
encouraged. The helium dwarf nova V803 Cen is undergoing an extremely
bright superoutburst, showing prominent superhumps. CCD observations of
such targets are a relatively easy task for a 20-40cm telescope; simply
take as many CCD frames (with exposure times 10-30 sec) as possible,
spanning several hours per night. The only requirements are the weather
and your patience! If you need more help on the observing technique,
please feel free to ask on the vsnet-campaign list.
CI Aql = the recurrent nova Aql 1917,2000 seems to have entered the
rapid decline stage. Observations at all wavelengths are encouraged at
this very important moment of recurrent nova evolution. Time-series CCD
observations at all binary phases would clarify the evolution of eclipse
profile, necessary for modelling the binary parameter.
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 behavior of
some R CrB stars, recent supernovae, eta Carinae etc. The VSNET light
curves have been also greatly updated. Please visit and enjoy the new
feature of the VSNET Web Page.
Sample light curve: omicron Cet = Mira
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/LCs/index/CETomicron.html
Sample light curve: SS Cyg (famous dwarf nova)
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/LClast/index/CYGSS.html
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VSNET Weekly Campaign Summary
*** Last week news ***
(new targets)
V893 Sco (RA = 16h14m45.26s, Dec = -28d39m30.3s)
As reported by B. Monard on 29 May, the eclipsing dwarf nova below
the period gap, V893 Sco occurred an outburst (12.7 mag on 29 May)
(vsnet-campaign 147). The fading was confirmed on 31 May.
The outburst was likely a normal outburst (vsnet-campaign 153).
V803 Cen (RA = 13h23m44.5s, Dec = -41d44m30.1s)
The helium dwarf nova V803 Cen occurred a bright outburst
(13.4 mag on 1 June) (vsnet-campaign 158). The further brightening
(12.6 mag) was confirmed through the observation by A. Pearce
on 2 June. It indicates the outburst is a superoutburst
(vsnet-campaign 163). The object is now in outburst.
No time-series observation is reported in vsnet-campaign.
The variation on this outburst should be confirmed.
V2051 Oph (RA = 17h08m19.1s, Dec = -25d48m31.1s)
The observation on 2 June by P. Williams showed this eclipsing
SU UMa-type dwarf nova was slightly brighter than quiescence
(14.3 mag on 2 June) (vsnet-campaign 161), however, the observation
by A. Pearce, >14.5mag on 2 June, indicates it was no major outburst
(vsnet-campaign 165).
V660 Her (RA = 17h42m07.3s, Dec = +23d47m37.3s)
As reported by J. Pietz, the SU UMa-type dwarf nova V660 Her
occurred a superoutburst (14.34 mag on 2 June), and he also detected
two humps with the amplitude of ~0.2 mag and the period of ~0.073 d
(vsnet-campaign 166). The object is now in superoutburst.
More observations are urged to study the superhump evolution.
(continuous targets)
CI Aql (RA = 18h52m03.6s, Dec = -01d28m38.9s)
Between May 29.59 and 29.80 UT, T. Kato reported a short-term
variation, fading and rising, was present in the combined data observed
by Kyoto team and S. Kiyota (vsnet-campaign 146). The object continued
to fade after the peak on May 23 (vsnet-campaign 160), and then, has
shown more rapidly fading since about 1 June (vsnet-campaign 168).
The decline rate reached 0.3 mag/d. On the declining trend, an
eclipse-like feature was present around (slightly earlier) the predicted
secondary eclipse (vsnet-campaign 171).
The eclipses will be able to clear in this rapid decline.
The observations on any phase are encouraged.
HS Vir (RA = 13h43m38.5s, Dec = -08d14m04.1s)
HS Vir was reported at 15.0 on 4 June, at the terminal stage of the
current superoutburst (vsnet-campaign 173).
BD Pav (RA = 18h43m12.0s, Dec = -57d30m45.1s)
The outburst seems to become considerably longer than the 1998 one
(vsnet-campaign 164). It is now in outburst.
The outburst lasts for at least 10 days. Is this an outburst of
a SS Cyg-type dwarf nova? Time-series photometry is strongly urged.
XTE J1118+480 (RA = 11h18m10.9s, Dec = +48d02m12.9s)
Using the data observed by VSNET collaboration team between
JD 2451690 and 2451699, the period of 0.1703(1) was calculated
(vsnet-campaign 174). The hump is still prominent and the short time
fluctuations are also present. In this period (JD 2451690 - 2451699),
the data shows no significant decline trend (vsnet-campaign 169).
No one can predict the future activity of this X-ray nova.
More observations are encouraged.
*** General information ***
V893 Sco
eclipse ephemeris, see [vsnet-campaign 148]
CI Aql
eclipse ephemeris, see [vsnet-campaign 159]
(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