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[vsnet-campaign-news 7] News from VSNET No. 7
*** 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. 19, 2000, as VSNET campaign circulation 234.
Several interesting dwarf novae are reported in outburst, and followed
by a number of observers. V893 Sco is among such objects, which had been
"lost" until the rediscovery by Katsumi Haseda (VSOLJ, Japan; please refer
to the IAU Information Bulletin on Variable Stars 4585). The system soon
turned out to be a rare, eclipsing dwarf nova below the period gap (orbital
periods less than 2 hours). Since most of dwarf novae below the period gap
are known to show superoutbursts (long, bright outbursts exhibiting brightness
modulations called "superhumps"), the expected ocurrence of superoutburst in
V893 Sco has been enthusiastically sought. Eclipsing systems among SU UMa
type dwarf novae have been providing unique information of the outbursting
accretion disk through the analysis of eclipse light curves. Those who may
be interested in superhumps and SU UMa stars, please refer to:
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/DNe/superhump.html
Good recent examples of eclpsing SU UMa-type dwarf novae, followed by
the VSNET Collaboration team, can be found at:
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/DNe/tmvz85.html
(TmzV85 = IY UMa, recently discovered eclipsing SU UMa-type dwarf nova,
originally reported by Kesao Takamizawa as a possible dwarf nova).
and
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/DNe/dvuma9912.html
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.
Eclipses in CI Aql = the recurrent nova Aql 1917,2000 have become more
prominent, as expected from its fading. Seiichiro Kiyota obtained a wonderful
eclipse light curve on June 15. 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).
The on-line light curves at the VSNET Website have been also greatly
updated by courtesy of the AFOEV (Association Francaise des Observateurs
d'Etoiles Variables) and the VSOLJ (Variable Star Observers' League in Japan).
Light curves drawn from more than 2 million and 1.4 million observations,
respectively, can be now easily browsed. Light curves constructed from
reports to VSNET have been continuously updated, too.
AFOEV light curve entry page:
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/AFOEV/LCs/index/index.html
VSOLJ light curve entry page:
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/VSOLJ/LCs/index/index.html
VSNET light curve entry page:
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/LCs/index/index.html
Select the constellation name from these pages, and select the variable
star name. By clicking "years" button, such as [1995], under each light
curve, you can reach the desired enlarged segment of the light curve.
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VSNET Weekly Campaign Summary
*** Last week news ***
(new targets)
FX Cep (RA = 21h03m12.5s, Dec = +66d10m51.2s)
T. Vanmunster performed a CCD photometry of FX Cep which is
undergoing an outburst, on Jun 17/18. During 3.7 hours run, the
object, at 15.5mag, did not show any periodic signals (vsnet-campaign 227).
He mentioned this result seems to support FX Cep's classification
as an UGSS-type dwarf nova, although more intensive observations
are required.
NSV02872 (RA = 06h14m08.2s, Dec = +45d30m29s)
This ROSAT-selected objects are put on the long-term vsnet-campaign
(monitoring for outburst) program (vsnet-campaign 230).
(see, http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-chat/msg03107.html)
PT Per (RA = 02h42m51.2s, Dec = +56d41m31s)
This ROSAT-selected objects are put on the long-term vsnet-campaign
(monitoring for outburst) program (vsnet-campaign 230).
(see, http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-chat/msg03113.html)
V893 Sco (RA = 16h14m45.26s, Dec = -28d39m30.3s)
According to R. Stubbings, the eclipsing dwarf nova (SU UMa candidate)
below the period gap is in outburst at 12.6mag on June 19
(vsnet-campaign 231). The present brightness suggests a normal
outburst, but no one knows whether this outburst evolves into a
superoutburst ?!
V436 Cen (RA = 11h13m58.2s, Dec = -37d40m45.0s)
Although the season is ending, the SU UMa-type dwarf nova V436 Cen
is undergoing a rare outburst at 11.9 mag on 19 June (vsnet-campaign 233,
vsnet-alert 4998). The last outburst (normal outburst) was observed
around 2000 Jan. 1, reaching mv=11.8. The last reported superoutburst
occurred in 1998 October (vsnet-alert 4998).
The present brightness does not exclude the possibility of a
superoutburst.
(continuous targets)
V1494 Aql (RA = 19h23m05.4s, Dec = +04d57m20.1s)
A. Retter reported that his observation during 3 nights in June
revealed the evidence for a periodicity of 1.5 hours with the variation
amplitude of 0.05mag (vsnet-campaign 207). L. Cook also detected
the periodic variation (P=91min) and the amplitude of about 0.04mag
(vsnet-campaign 216, 222). He also reported the object showed
0.109mag decline over the 24 hours (vsnet-campaign 222).
The current magnitude is about 10.4mag. More observations are
encouraged.
XTE J1118+480 (RA = 11h18m10.9s, Dec = +48d02m12.9s)
From the data from JD2451700 to 2451710 observed by VSNET collaboration
team (Kyoto team and L. Cook), the period is calculated as 0.17062(11)d.
The ten days averaged light curve shows a flat peak and a flat bottom.
The amplitude of the humps does not change from the previous one
(about 0.08 mag) (vsnet-campaign 210).
The hump is still prominent. To study the hump evolution and
optical QPOs, more observations are urged.
V803 Cen (RA = 13h23m44.5s, Dec = -41d44m30.1s)
Strong fluctuations around 14 - 13 mag were observed (vsnet-campaign 208,
218, 224, 228). Observations are strongly needed, since such strong
day-scale fluctuation tends to rapidly damp during the slow fade
(vsnet-campaign 208).
CI Aql (RA = 18h52m03.6s, Dec = -01d28m38.9s)
The light curve on June 15 by Kyoto team shows a transient brightening
of 0.3 mag centered at June 15.79 UT superimposed on an apparent rise
from the primary minimum (vsnet-campaign 214). The analysis of combined
data by S. Kiyota (Tsukuba, Japan) and the Kyoto team on Jun. 15 has
yielded a detection of the primary eclipse minimum. The eclipse was
0.3mag deep. A preliminary analysis yielded a mid-eclipse time of
15.597 UT, while the prediction (based on the epehemeris in IBVS 4232,
Mennickent and Honeycutt) was 15.586 UT (vsnet-campaign 220).
More observations are strongly needed to confirm the positive
detection of the eclipse O-C.
BD Pav (RA = 18h43m12.0s, Dec = -57d30m45.1s)
The eclipsing SS Cyg-type dwarf nova BD Pav has just faded from the
recent rare outburst (vsnet-campaign 223).
V493 Lyr (RA = 19h01m31.9s, Dec = +42d54m46.5s)
T. Vanmunster reported the light curve on Jun 12/13 is showing
some modulation, although he wouldn't attribute it to superhumps
(vsnet-campaign 226). He mentioned it seems V493 Lyr indeed
is a long-period UGSS-type dwarf nova, as also suggested by T. Kato,
in (vsnet-campaign 194).
Now it is in fading phase. The current magnitude is about 15.
LX Ser (RA = 15h37m59.1s, Dec = +18d51m43.9s)
The eclipsing cataclysmic variable LX Ser has been reported fainter
(>15mag) since June 11. Please continue monitoring to see whether
the star becomes brighter, as in early June (vsnet-campaign 229).
*** Future schedule ***
BL Lac campaign (July 17 - August 11)
Massimo Villata, Gino Tosti, and Enrico Massaro organize an
optical campaign on BL Lac contemporaneous with the high-energy
campaign involving X-ray and TeV observatories such as BeppoSAX,
RXTE, STACEE, CAT, HEGRA. Their goal is high-density and
high-precision coverage, possibly in two optical bands (B and R).
Observers interested in participating to this optical campaign are
invited to contact with M. Villata (villata@to.astro.it).
[vsnet-campaign 204]
*** General information ***
CI Aql
eclipse ephemeris, see [vsnet-campaign 203]
XTE J1118+480
new light curve is seen at:
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Xray/xtej1118-camp.html
BD Pav
eclipse ephemeris, see [vsnet-campaign 223]
V893 Sco
eclipse ephemeris, see [vsnet-campaign 231]
(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