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[vsnet-campaign-news 51] News from VSNET 51
*** News from VSNET ***
K. Haseda revealed that WR 104, which was reported to be
accompanied by a dust pinwheel nebula, is a large-amplitude
variable star.
For more detail information about these objects,
see below, "VSNET Weekly Campaign Summary" of the last week.
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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.
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.
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).
Regards,
Taichi Kato
On behalf of the VSNET administrator team
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The following was issued on Apr. 23, 2001, as VSNET campaign circulation 870.
[Note a large part of detailed information is posted to vsnet-campaign
sub-lists].
VSNET Weekly Campaign Summary
*** Last week news ***
(new targets)
WR104 = HadV82 (RA = 18h02m04s.0, Dec = -23d37'41")
K. Haseda reported the discovery of a new variable star (HadV82).
The star is identified with an IR-luminous WR-type star, WR104.
The striking spectroscopic variability WR104, probably associated
with photometric fading, was previously reported by Crowther, MNRAS 290,
L59 (1997). The suggested photometric fading by Crowther (1997)
was based on a comparison with previously published photometry, and was
not very conclusive. Crowther (1997) also added that past research had
found no infrared variability. Crowther (1997) suggested this phenomenon
to be dust condensation as seen in R CrB-type stars, but the nature of
variation remained an mystery. The present discovery by Haseda has not only
shown that the object is indeed variable in optical, but also that bright
and faint states appear interchangebly, with a characteristic time scale
of one to a few years (vsnet-campaign 863). Since the rotation period
of the spiral (Tuthill et al. 1999, Nature 398, 487: "A dusty pinwheel
nebula around the massive star WR 104") is reported to be 220 d,
observations at higher frequencies are encouraged (vsnet-campaign 865).
Based on the detailed chart prepared by T. Watanabe, K. Haseda further
provides the updated set of photographic photometry which shows the
variability range is 11.8-(14.5p (vsnet-campaign 868).
HS Vir (RA = 13h43m38.5s, Dec = -08d14m04.1s)
Ths SU UMa-type dwarf nova HS Vir experienced an outburst as
reported by R. Stubbings on April 16 (14.0mag). The last
superoutburst was observed in 2000 May, and no outbursts brighter
than 14.5 were observed since then (vsnet-campaign 861).
The outburst continued until April 20 when A. Pearce reported
<15.0mag (vsnet-campaign-dn 672).
V550 Cyg (RA = 20h05m05s.21, Dec = +32d21'21".0)
The SU UMa-type dwarf nova V550 Cyg may be in outburst, as reported
by G. Poyner on April 21 (14.0mag). The last outburst of V550 Cyg
occurred in 2000 August (mv=14.8, T. Kinnunen), which turned out to
be a superoutburst. If the present possible outburst turns out to
be a superoutburst, the supercycle of V550 Cyg would be ~240 d
(vsnet-campaign 864).
PKS2155-304 (RA = 21h58m52s, Dec = -30d13'31")
As reported by B. Monard on April 23, this blazar has suddenly
faded from 13.2 to 13.9 (vsnet-campaign-blazar 185).
(continuous targets)
IX Dra (RA = 18h12m32s.2, Dec = +67d04'41")
The superoutburst continues. The current magnitude looks
fainter than 15.6 (vsnet-campaign-dn 677).
AK Cnc (RA = 08h55m18s.49, Dec = +11d18'06".2)
The superoutburst continues. The current magnitude is about 14.2
(vsnet-campaign-dn 669, 674, 675, 680).
ST Cha (RA = 10h47m31s.3, Dec = -79d27'17")
An observation by R. Stubbings on April 16 indicates an outburst
(14.0mag) of this cataclysmic variable (vsnet-campaign-dn 670).
GK Per (RA = 03h31m12s.50, Dec = +43d54'17".8)
The brightening to 12.7mag was reported during the last week
(vsnet-campaign-ip 51).
omega CMa (RA = 07h14m48s.6, Dec = -26d46'22")
T. Kato noticed 3 Pup = NSV17577 is a suspected variable, so
this star should not be used as a comparison star (vsnet-campaign-be 100,
101, 102).
RX J1155.4-5641 (RA = 11h55m27.6s, Dec = -56d41'48")
The object rapidly faded from the outburst (vsnet-campaign-dn 671).
DI UMa (RA = 09h12m22s.16, Dec = +50d49'39".1)
G. Poyner reported that DI UMa experienced an outburst at 15.0mag
on April 20 (vsnet-campaign-dn 685). M. Uemura, the Kyoto team,
confirmed the outburst on April 22 (vsnet-campaign-dn 687).
The light curve not showed clear superhumps but some modulations
with an amplitude of 1.5mag (vsnet-campaign-dn 690).
TU Crt (RA = 11h03m36s.50, Dec = -21d37'45".6)
The superoutburst plateau phase continued until April 18,
and then, entered a rapid fading phase (vsnet-campaign-dn 666,
673, 678, 683, 689).
V803 Cen (RA = 13h23m44.5s, Dec = -41d44'30".1)
The object showed fluctuation between 13.7-14.5 (vsnet-campaign-dn 667,
679), and then, experienced a bright (12.7mag) outburst on April 20
as reported by A. Pearce. The last bright outburst was observed
on 2001 Jan. 4 (vsnet-campaign-dn 681). On April 21, the outburst
was terminated as reported by B. Monard (vsnet-campaign-dn 688).
MKN 421 (RA = 11h04m27s, Dec = +38d12'32")
The strong activity is still continues (vsnet-campaign-blazar 184).
3C 279 (RA = 12h56m11s.1, Dec = -05d47'20")
The strong activity continues (vsnet-campaign-blazar 179, 180, 182)
T. Balonek reported it is now two magnitudes brighter and
fluctuated between R = 14.04 and 13.92 during April 18 night
(vsnet-campaign-blazar 181).
CR Boo (RA = 13h48m55s.42, Dec = +07d57'30".3)
The bright outburst continued until April 21 (vsnet-campaign-dn 676,
686).
DW Cnc (RA = 07h58m56s.80, Dec = +16d16'48".2)
M. Uemura reported that the object has remained the brightness
over one month. The time-series monitoring campaign by the Kyoto
team, R. Novak, and J. Pietz yields the periodicity of 0.04855 or
0.0268 d. The object is still very active (vsnet-campaign 862).
V445 Pup (RA = 07h37m56s.88, Dec = -25d56'59".1)
The object is gradually fading (vsnet-campaign-nova 282, 283, 284).
V1504 Cyg (RA = 19h28m55.87s, Dec = +43d05'39".9)
The superoutburst terminated during the last week
(vsnet-campaign-dn 668).
SN 2001X (RA = 15h21m55s.46, Dec = +05d03'43".1)
This SN is gradually fading now (vsnet-campaign-sn 171).
KR Aur (RA = 06h15m45s.05, Dec = +28d34'16".0)
The brightening continues. The current magnitude is about 14.0
(vsnet-campaign-nl 12).
OJ287 (RA = 08h51m57s, Dec = 20d17'59")
The object continues the gradual brightening (vsnet-campaign-blazar 183).
BZ Cam (RA = 06h29m34s.49, Dec = +71d04'39".5)
BZ Cam is slowly recovering from the faint state (vsnet-campaign-nl 13).
*** Future schedule ***
CR Boo and V803 Cen campaign conducted by J. Patterson
in [vsnet-campaign-dn 640 and vsnet-campaign 852]
"We have started a photometry campaign on the helium dwarf novae CR
Boo and V803 Cen, designed mostly to trace the extremely rapid up-and-down
excursions of these stars. Right now both stars are in "cycling states",
in which they go back and forth between about 13.4 and 14.6, with a period
somewhere in the range 18-24 hours. Naturally this is a really awkward
period to study, unless you have observers spread around at various
longitudes. Also, the nature of this variation is still not known; it
could be just a spectacularly short dwarf-nova recurrence period, or some
(other) kind of disk oscillation not yet found among the more familiar
hydrogen-rich CVs. For these reasons, we eagerly seek observations of
these two fascinating helium stars over the course of our campaigns (about
3 more weeks)."
RZ LMi campaign conducted by J. Patterson on April 2001
For more information, see [vsnet-campaign 718, vsnet-campaign-dn 429].
Elizabeth and Frederick White Workshop
AGN variability across the Electromagnetic Spectrum
25 - 29 June 2001 Sydney, Australia
For more information, see [vsnet-campaign-blazar 168].
Two Years of Science with Chandra *
* This meeting will also be the 12th Annual Maryland Astrophysics
Conference
September 5-7, 2001
For more information, see [vsnet-campaign-xray 66]
*** General information ***
3C279
The light curve presented by T. Balonek;
http://blazar.colgate.edu/astronomy/quasaroptical.html
On that page there is a link to magnitude compilations at:
http://blazar.colgate.edu/~tbalonek/optical/listmags
[vsnet-campaign-blazar 181]
WR104 = HadV82
finding chart presented by T. Watanabe;
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-j/jpg00010.jpg
[vsnet-campaign 869]
(This summary can be cited.)
Regards,
Makoto Uemura
vsnet-adm@kusastro.kyoto-u.ac.jp
Return to Daisaku Nogami
vsnet-adm@kusastro.kyoto-u.ac.jp
VSNET Home Page