V4641 Sgr



V4641 Sgr: remarkable flaring state!!

Dear Colleagues,

    We (SSO) have just sended to VSnet , time-series photometry on July 7 (UT)
  Although the observation was slightly affect by the
clouds, V4641 Sgr shows *dramatic* repeated flare-like brightenings
by 0.5 mag.  The typical e-folding decay time of the flares was only
a few minutes.  The rise usually took 30 s to 2 min.  A 0.3 mag fading
within 40 s(!) was also observed in one of these flares.  Such a dramatic
activity reminds us of the repeated flaring state of the microquasar
GRS 1915+105 observed in X-rays. 
  Such dramatic variation of any variable star was totally
unprecedented and unexpected. 


Run Time Serie 20020707


Run Time Serie 20020713

The data show a monotonic trend, and no apparent short-term or flare-like
beightenings were recorded.  The object may have calmed down,

Astrophysics abstract astro-ph/0208146