Electronic Telegram No. 12
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html


XTE J1550-564
     P. Woudt, University of Cape Town (UCT); and P. Charles
and I. C. Shih, University of Southampton, report that,
following the INTEGRAL detection of renewed hard x-ray
activity in the blackhole transient XTE J1550-564, they
obtained high-speed photometry of the optical counterpart
(Jain et al. 2001, Ap.J. 554, L181) with the South African
Astronomical Observatory 1.9-m telescope (+ UCT CCD) during
25 min on Mar. 27.  The object appeared at V about 18 (close
to its maximum during the 2000 outburst) and it displays
significant variability on timescales of 1-2 min, including
a flare of about 0.5 mag lasting < 20 s.  Further observations
of this microquasar at infrared and radio observations are
strongly encouraged.


NOTE: These 'Central Bureau Electronic Telegrams' are intended to
      be preliminary announcements of items that later appear in the
      formal IAU Circulars.  Citations should normally be made to IAUCs
      rather than to CBETs.

                         (C) Copyright 2003 CBAT
2003 March 29                     (CBET 12)               Daniel W. E. Green