[vsnet-campaign-news 279] VSNET Weekly Campaign Summary
Makoto Uemura
uemuram at hiroshima-u.ac.jp
Mon Jun 27 19:52:01 JST 2005
VSNET Weekly Campaign Summary
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*** Headlines ***
Strong activity of a black hole binary! ----- V4641 Sgr
*** Last week news ***
(new targets)
V4641 Sgr (RA = 18h19m21s.58, Dec = -25d24'25".1)
R. Stubbings found an outburst of a black hole X-ray binary,
V4641 Sgr on 24.371 June (12.2mag) (vsnet-alert 8463). After the
1999 giant outburst, optical outbursts of V4641 Sgr were recorded in
May 2002, August 2003, and July 2004. Interestingly, the object
frequently showed rapid variations during the outbursts in
2002--2004 (vsnet-alert 8464, vsnet-campaign-xray 299).
Observations by the Kyoto team on 24 June showed that the object was
rather calm and monotonously faded (vsnet-alert 8465, 8470). After
this run, B. Monard performed time-series observations, which showed
oscillations superimposed on a gradual brightening. At 24.9236
June, a giant flare/flash was observed, lasting for less than one
exposure (28sec) (vsnet-alert 8466). M. Uemura commented that the
fading and brightening trend on 24 June may be due to an obscuration
by a secondary star (vsnet-campaign-xray 312, 313).
On 25 June, the object had brightened further (11.7mag, 25.367
June, by R. Stubbings). Short-term variability can be observable
even by visual observers (vsnet-alert 8467, 8469). J. Swank
reported that an RXTE observation June 25.338-25.360 found a low
level of X-ray activity at the level of 5-10 mCrab, approximately,
in the form of flares, similar to those observed in previous years
(vsnet-alert 8468, 8476). K. Nakajima and H. Maehara obtained light
curves showing several flares, and then, the light curve obtained by
B. Monard was filled by rapid flares (vsnet-alert 8472, 8474).
On 26 June, the object faded to 13.0-13.4mag, but the active phase
continues (vsnet-alert 8473). The HETE/WXM detected an X-ray flare
close to V4641 Sgr. It was probably from V4641 Sgr (vsnet-alert
8477). Infrared observations are planned on 27 June with the 2.2m
hawaii telescope by Dr. Pitts (vsnet-alert 8478).
Time-series observations are strongly encouraged in all
wavelengths.
NSV24607 (RA = 18h50m03s.57, Dec = -26d24'15".38)
S. Otero reported: "The enigmatic eclipsing (possibly symbiotic)
system AS 325 (NSV 24607) is fading dramatically right now, heading
for its minima around July 18th. This cycle, a fading event started
by the end of April, more than a month before the predicted eclipse
ingress. The current magnitude is V= 11.4, fainter than ever and
more than 20 days before mideclipse. Dr. Steve B. Howell from WIYN
Observatory is taking spectra of AS 325. Multicolor photometry
would be very interesting to follow these changes, specially now
that the fading is going further than expected from the "normal"
eclipse only (vsnet-alert 8471).
V841 Oph (RA = 16h59m30s.26, Dec = -12d53'26".8)
M. Moriyama has pointed out that V841 Oph (Nova Oph 1848) is
fainter than its "canonical" post-outburst level (14.3:mag, 25.614
June). ASAS-3 data seem to generally support this fading trend,
although it is not still clear whether Moriyama's observation either
reflects the overall change or a sudden fading (vsnet-alert 8475).
KK Tel (RA = 20h28m38s.46, Dec = -52d18'45".6)
R. Stubbings reported an outburst of a dwarf nova, KK Tel
(13.8mag, 25.427 June) (vsnet-campaign-dn 4444). The outburst is
likely a superoutburst (vsnet-campaign-dn 4447).
RX Vol (RA = 08h39m32s.30, Dec = -66d17'39".2)
R. Stubbings reported an outburst of a dwarf nova, RX Vol
(14.8mag, 25.389 June) (vsnet-campaign-dn 4445). The outburst is
likely a superoutburst (vsnet-campaign-dn 4447).
V485 Cen (RA = 12h57m23s.30, Dec = -33d12'06".8)
The well-known ultra-short period SU UMa star (below the period
minimum) is undergoing an outburst, as reported by R. Stubbings
(14.8mag, 26.451 June) (vsnet-campaign-dn 4446).
(old targets)
V1663 Aql (RA = 19h05m12s.50, Dec = +05d14'12".0)
The fading continues (vsnet-campaign-nova 1663).
ASAS 160048-4846.2 (RA = 16h00m47s.43, Dec = -48d46'07".6)
M. Uemura performed a preliminary period analysis for superhumps
observed by B. Monard, and reported: "The behavior of superhumps is
quite similar to that observed in RZ Leo, another WZ Sge-type dwarf
nova having a long orbital period. Superhumps rapidly evolved
during 9-12 June. After this early phase, the superhump period began
increasing, which is typical for WZ Sge stars. This phase was
terminated on Jun 18, and then, the period decreased. In most cases
of WZ Sge stars, this phase transition occurs after terminations of
superoutbursts. In the case of RZ Leo, however, it occurred during
a superoutburst. And now, ASAS 160048-4846.2 also."
(vsnet-campaign-dn 4439, 4441)
SN 2005ay (RA = 11h52m48s.07, Dec = +44d06'18".4)
K. Nakajima reported 13.82C mag on 7.72873 April
(vsnet-campaign-sn 1011).
V378 Ser (RA = 17h49m24s.57, Dec = -12d59'59".2)
A. Takao reported early observations around the discovery of the
nova; <13.0C on 15.847 March and 12.8C on 20.842 March
(vsnet-campaign-nova 1664).
*** Future schedule ***
AAVSO campaign for SDSS161033
for more information, see:
http://www.aavso.org/publications/alerts/alert319.shtml
[vsnet-campaign-dn 4442]
*** General information ***
V378 Ser
Image on March 30.818 UT by A. Takao:
http://www4.ocn.ne.jp/~drtakao/ASAS174924-1300.0.html
[vsnet-campaign-nova 1665]
(Recent astro-ph preprints)
ROTSE-III CVs report
http://arXiv.org/abs/astro-ph/0506442
[vsnet-campaign-dn 4440]
Recent astro-ph on SN 2004gt
http://arXiv.org/abs/astro-ph/0506436
[vsnet-campaign-sn 1007]
Spitzer observation of a plateau of an SN II-P
http://arXiv.org/abs/astro-ph/0506407
[vsnet-campaign-sn 1008]
SN Ia progenitor
http://arXiv.org/abs/astro-ph/0506415
[vsnet-campaign-sn 1009]
SN 2004gt progenitor
http://arXiv.org/abs/astro-ph/0506472
[vsnet-campaign-sn 1010]
V660 Her
http://arXiv.org/abs/astro-ph/0506487
[vsnet-campaign-dn 4443]
Catalog of Galactic Beta Cephei Stars
http://arXiv.org/abs/astro-ph/0506495
[vsnet-campaign-be 274]
EXO 2030+375 = V2246 Cyg
http://arXiv.org/abs/astro-ph/0506504
[vsnet-campaign-xray 298]
(This summary can be cited.)
Regards,
Makoto Uemura
Hiroshima University
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