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[vsnet-campaign-news 2] News from VSNET No. 2
*** 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 22, 2000, as VSNET campaign circulation 113.
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 maintained the bright state
at around magnitude 12.8, but has started fading.
CI Aql is the recurrent nova (= Nova Aql 1917, 2000), whose first-ever
recurrence was discovered by Takamizawa and Yamamoto, whose detection
and confirmation was announced via vsnet-alert 4695 and IAUC 7409.
The object is slowly fading around magnitude 10.0, with fluctuations
and possible emergence of eclipses.
Several other interesting dwarf novae are reported in outburst, and
followed by a number of observers.
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).
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VSNET Weekly Campaign Summary
*** Last week news ***
(new targets)
HT Cam
The outburst of a suspected SU UMa or IP, HT Cam = RX J0757.0+6306
was reported by T. Kinnunen and P. Schmeer on 15 May (vsnet-alert 4845,
4846). V. Simon reported it was back in quiescence and confirmed rapid
decline from outburst on 16 May. The feature of this outburst agree
with the previous one (vsnet-campaign 77). The decline rate is
very fast and possibly more than 5 mag/d. Now it is in quiescence.
V359 Cen
R. Stubbings reported that the dwarf nova V359 Cen was undergoing
the third historical outburst on 15 May (vsnet-campaign 70). The last
outburst was in 1999 July when the possible existence of superhumps
was reported. From A. Pearce's observation on 17 May, a 0.5mag decline
within two days was revealed (vsnet-campaign 86), and then, the outburst
is ongoing now. Time-resolved photometry is strongly encouraged.
KK Tel
This suspected SU UMa-type dwarf nova occurred a bright outburst
on 17 May (vsnet-alert 4860), and the outburst is ongoing now.
Time-resolved photometry is strongly encouraged.
CP Dra
The outburst of this poorly studied dwarf nova was reported by
T. Vanumunster on 15 May (vsnet-campaign 89, vsnet-alert 4851).
It has shown rather rapid decline to quiescence on 18, 19 May
(vsnet-campaign 107). Now it is in quiescence.
(continuous targets)
RX J1450.5+6403
The superoutburst is ongoing now. R. Novak performed period analysis
using his data and provided the period of 0.0602(2)d on 16 May
(vsnet-campaign 71). T. Vanmunster revised the superhump period to
0.0600(2)d using the data before 16 May obtained by CBA team
(vsnet-alert 4852). He also reported a slightly increased superhump
period of 0.0606(5)d using the data obtained by J. Kemp on May 18/19
(vsnet-alert 4870). The spectroscopic period of either 0.0588 or
0.0599 d was provided by Thorstensen (vsnet-alert 4848). The quiescent
photometry obtained at Nyrola observatory team shows a sharp periodicity
at 0.0289 d which is pretty close to the half of the spectroscopic
period. The feature is quite reminiscent of other short-period SU UMa
systems and possible eclipses are suggested (vsnet-campaign 81, 82).
D. Nogami analyzed their quiescent data just before the outburst
(7, 10, and 11 May) and provide a period estimation of 0.056 d
(vsnet-alert 4868). In the data obtained by R. Novak, there are
significant QPOs superimposed on the fading branch of superhumps
(vsnet-campaign 83). The QPOs are confirmed by T. Vanmunster
(vsnet-alert 4870).
Time-series observations are encouraged to detect the superhump
evolution, late superhumps, and QPO during final decline.
RX J0640-24
The outburst is ongoing now. W. Walker reported the possible
structure in his two hours light curve on 19 May, but the amplitude
is not more than 0.15 magnitudes (vsnet-campaign 97). It was
suggested that the object entered a rapid fading phase from 20 May
(vsnet-campaign 104). Further observations during this outburst
are urged.
BZ UMa
The rapid fading has been confirmed and no re-brightening has been
detected. It is now in quiescence.
CI Aql
A. Pearce reported an appreciable short-term variability
(vsnet-campaign 80). L. Kral's data revealed the object started to
brighten since May 12 (vsnet-campaign 84). The object showed smoothly
fading from peak, which was interrupted by the brightening on 15 May
(vsnet-alert 4857). The magnitude returned to 9.7mag, and then,
the object turned to decline from 18 to 20 May (vsnet-campaign 103).
Most recently, Kyoto team confirmed the linear 0.1mag rise in two hours
from the May 21 (vsnet-alert 4875).
Time-series photometry, particularly around eclipses, are
strongly encouraged.
XTE J1118+480
L. Cook reported the slight decline (0.12 mag compared with that of
March 31) and the data obtained at Kyoto also shows this tendency
(vsnet-campaign 96, 98, and 102). The ASCA data on May 11 (ASCA - VSNET
campaign) revealed a QPO at 0.115(2) (Hz), indicating the frequency
shifted from the previous value (vsnet-campaign 100). Using the
last week data, the longer period of 0.1713 d and its smaller amplitude
of 0.05mag was reported in [vsnet-campaign 111].
We should confirm whether the reported decline will continue or
interrupt by any other event.
*** General information ***
V359 Cen
coordinates, see [vsnet-alert 3216]
CI Aql
light curves obtained at Ostrava Observatory
(http://ostrava.astronomy.cz/)
http://ostrava.astronomy.cz/stars/ciaql/cien.htm
eclipse ephemeris, see [vsnet-campaign 92]
XTE J1118+480
power spectrum of the X-ray light curve with ASCA
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Xray/xtej1118-camp.html
preprint (R. I. Hynes et al. ApJ submitted) astro-ph/0005398
(This summary is reproduction free.)
Regards,
Makoto Uemura
on behalf of VSNET collaboration team
vsnet-adm@kusastro.kyoto-u.ac.jp
Return to Daisaku Nogami
vsnet-adm@kusastro.kyoto-u.ac.jp
VSNET Home Page