From: LARRY KLAES (ljk4_at_msn.com)
Date: Thu Aug 07 2003 - 07:22:55 PDT
----- Original Message -----
From: Taichi Kato
Sent: Thursday, August 07, 2003 5:45 AM
To: variable-star_at_skypub.com
Cc: tkato_at_kusastro.kyoto-u.ac.jp; vsnet-adm_at_kusastro.kyoto-u.ac.jp
Subject: AstroAlert: Galactic Microquasar V4641 Sgr Very Active!!
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This Is SKY & TELESCOPE's AstroAlert for Variable Stars
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Galactic Microquasar V4641 Sgr Very Active!!
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Dear Colleagues,
The Galactic microquasar (close binary system containing a black hole,
characterized by the presence of jet ejection) V4641 Sgr is now extremely
active. The object is reported to vary between mag 10 and 13 with short
time scales. The object may undergo a giant eruption (reaching at least
mag 8.8) in 1999 September. The flickering light observed now is possibly
originating from the inner(most) region of the accretion disk, close to
the black hole. This mean that you may even directly "see" the light
from the matter just falling into the black hole!
For more details first look at,
http://www.kusastro.kyoto-u.ac.jp/vsnet/Xray/v4641sgr03.html
and the links therein.
The object is located at 18:19:21.4, -25:24:25 (J2000.0).
The VSNET is conducting an international campaign on this object,
during the current activity phase. High time-resolution (better than
10-20s) CCD long time-series observations are extremely wanted!!
Regards,
Taichi Kato
VSNET Collaboration team
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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.
VSNET Home Page: http://www.kusastro.kyoto-u.ac.jp/vsnet/
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_at_kusastro.kyoto-u.ac.jp (VSNET administrator)
with a line "SUBSCRIBE vsnet-campaign." or your comment to join the
collaboration team.
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