The 2003 Outburst of the Galactic microquasar
V4641 Sgr!
(Animation by Jean-Yves Beninger, south is up)
(Optical flash and fainter state)
(Peter Nelson's V-band CCD image; suggested comparison stars
are marked. The CCD operation by Peter Nelson is on loan from the AAVSO,
funded by the Curry Foundation).
V4641 Sgr outburst!!!
[vsnet-alert 7818]
V4641 Sgr active again!
Forwarded message from Rod Stubbings. Please give it a go!!
Subject: [vsnet-outburst 5773] V4641 Sgr active!
V4641 Sgr is brighter than usual and could be
in an active state once again.
SGRV4641 030801.376 121 Stu.RASNZ
Regards,
Rod Stubbings
[vsnet-alert 7819]
As reported vsnet-alert 7818 August 01, V4641 Sgr appears active again.
STAR YYYYMMDD(UT) MAG OBSERVER
SGRV4641 20030803.393 <100 WPX
SGRV4641 20030803.434 133 WPX
SGRV4641 20030804.422 <100 WPX
SGRV4641 20030804.494 118 WPX
SGRV4641 20030804.506 118 WPX
Regards
Peter Williams
Heathcote NSW
20x80mm binoculars
[vsnet-alert 7820]
The initial short disturbances on the light curve of V4641 Sgr have
taken hold. The system is presently shining at 11.5R and we can expect
to see some interesting fluctuations in the light curve now.
This is an early night target.
Berto Monard
CBA Pretoria
Timeseries are presently under way at CBA Pretoria
[vsnet-alert 7821]
We have just submitted the following to 'The Astronomer's Telegram'
(ATEL #170):
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Subjects: Optical, Binaries, Black Holes, Transients
SMARTS consortium observations of the black hole candidate V4641 Sgr with
the 1.3m telescope at CTIO + ANDICAM instrument from UT 2003 Aug 4.00
indicate that the source is starting a new outburst. The B, V, and I
magnitudes were 12.8, 12.6 and 12.2, which is 1.1, 1.1 and 1.1 magnitudes
above the predicted quiescent value. I-band data folded on the orbital
period show activity as early as UT 2003 Aug 1.95. Observations at all
wavelengths are encouraged. Our recent optical data from SMARTS are posted
at http://phoenix.astro.yale.edu/buxton/smarts/v4641_2003outburst.html
---------------------------------------------------------------------------
[vsnet-alert 7822]
V4641 Sgr: short-term violent variation!
Dear Colleagues,
The VSNET Collaboration has received a substantial number of time-resolved
observations during (and preceding) the current activity phase.
Up to August 3, the object was rather calm, with a slightly elevated
baseline and occasional small flares. On August 4, however, the object
showed violent variations! The variations (mainly received from Kiyota-san,
Tsukuba, Japan) are composed of short-term variations with time scales
of a few minutes to an hour. The light curve is characterized by recurrent
occurences of gradual rise (with violent fluctuations) and a sudden drop.
The light curve, as a whole, resembles those of violently varying state
just after the beginning of
the 2002 active phase. Please keep watching
the object closely. For CCD observers, please use short (usually less
than 15s) integration times when possible, to record the short-term
variations!
We will inform the ongoing activity in vsnet-campaign-v4641sgr list
unless a special change is recorded.
Regards,
Taichi Kato
VSNET Collaboration team
V4641 Sgr, also active in X-rays!
[vsnet-alert 7823]
V4641 Sgr, also active in X-rays!
Date: Wed, 6 Aug 2003 22:53:05 -0400 (EDT)
From: Charles Bailyn
Subject: X-ray observations of V4641 Sgr
As you see below, there is exciting activity in the X-ray as well.
More X-ray observations are scheduled for the next few days, so
please encourage everyone to keep looking at this source!
- Charles Bailyn
------------------------------------------------------------------------------
The Astronomer's Telegram http://atel.caltech.edu/
==============================================================================
ATEL #171 ATEL #171
Title: X-ray and Optical Activity in V4641 Sgr (=SAX 1819.3-2525)
Author: C. Bailyn, D. Maitra, M. Buxton, L. Jeanty (Yale), D. Gonzalez
(CTIO)
Queries: bailyn@astro.yale.edu
Posted: 6 Aug 2003; 22:55 UT
Subjects: Infra-Red, Optical, X-ray, Black Holes, Transients
V4641 Sgr is now active in X-rays, and activity continues in optical/IR
bands. A ~1 kilosecond dwell with the RXTE/PCA taken August 5 2003 starting
at UT 01:18 shows flux varying from 20 to 35 mCrabs. On August 6 between
UT 08:43 - 09:31 the source was in a highly active flaring state, with
flares of up to 100 mCrabs erupting on timescale of 10-30 seconds. Observations on August 6 from UT 10:23 - 11:13 did not show large flares, but rather
a state similar to that observed in the August 5 dwell. Similar activity
was also seen in optical/IR observations by the SMARTS consortium, using
the 1.3m telescope at CTIO with the ANDICAM instrument. On August 6 the
source brightened in the V band from magnitude 12.4 to 10.9 between UT
00:00 and UT 05:15. The source became somewhat bluer during this rise:
over the same period the K band brightened by only 1.1 magnitudes. Flares
and dips of several tenths of a magnitude were observed on timescales of
<3 minutes.
Continued Short-Term Variation!
(vsnet-campaign-v4641sgr 194)
V4641 Sgr short-term variations
We performed CCD time-series observation for 4 hours last night
at the Ouda observatory with a 60-cm telescope.
Our B-band observation was done with an exposure time of 2 sec
yielding a time resolution of 4 sec.
The light curve shows 100-sec time-scale variations
with amplitudes of 0.05-0.10 mag. A relatively large hump was also
seen around August 6.62 UT (amplitude ~ 0.2mag).
The light curve is similar to that we observed on 2002 May 24,
around the maximum of the last active state.
There is a sign of further shorter time-scale variations.
More detailed analysis is now ongoing.
We will continue observation at Ouda tonight if we have clear sky.
Regards,
Makoto Uemura
Optical Flash!
(vsnet-campaign-v4641sgr 198)
V4641 Sgr from Berto Monard and Lew Cook
Dear Colleagues,
The VSNET Collaboration further received further observations from
Berto Monard and Lew Cook. The object has become even more active
with violent short-term variations. The full amplitude of the variations
now reached 1.5 mag. There are evident strong oscillations before the
object suddenly fades. On August 6, there was an apparent "optical flash",
which is simlar to the
event observed on 2002 July 7
(Uemura et al., PASJ in press).
The rise of the "flash" took less than 30 seconds,
and the amplitude is more than 0.7 mag.
The entire data now being intesively analyzed by Uemura-san.
Regards,
Taichi Kato
VSNET Collaboration team
Papers by Uemura et al.
Get the preprint!
Get the preprint [PDF]!
Get the preprint (for the 2002 event)!
Get the preprint (2002 event) [PDF]!
Useful links
Rupen's page
SMARTS page
Light curve (requires Java 1.1)
Light curve
VSNET data search
Search!
VSOLJ news (in Japanese)
Link to VSOLJ News on V4641 Sgr (2003 event)
Link to VSOLJ News on V4641 Sgr (2002 event)
Link to VSOLJ News on V4641 Sgr (1999 event)
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