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IAUC 7425: 2000cj; LMC X-3

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                                                  Circular No. 7425
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
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SUPERNOVA 2000cj IN NGC 6753
     Robert Evans, Hazelbrook, N.S.W., reports the visual discovery
of an apparent supernova (mag about 14.8) on May 14.7 UT with a
0.31-m reflector.  A CCD image taken in bright moonlight by T.
Dobosz, Bankstown, N.S.W., with a 0.28-m Schmidt-Cassegrain
telescope on May 15.6 shows the new star superimposed upon a spiral
arm of the galaxy, and a measurement of this image by G. L. White,
Nepean Centre for Astronomy, Kingswood, N.S.W., yields the
following position for SN 2000cj:  R.A. = 19h11m27s.49, Decl. =
-57o03'14".1 (equinox 2000.0), which is about 35" east and 19"
south of the nucleus of NGC 6753.  Position end figures for SN
2000cj (mag 14.7) measured by R. H. McNaught at Siding Spring (from
a CCD image obtained by R. Langersek, Macgregor, Qld., with a
0.25-m Schmidt-Cassegrain telescope on May 15.62) are 27s.68, 19".4
(reduction using ten USNO-A2.0 stars, rms 0".4), with the offset
being 33" east and 22" south of the galaxy center.  McNaught
confirms that nothing appears at this position on the ESO B, ESO R,
and SERC J surveys.  N. Suntzeff, Cerro Tololo Interamerican
Observatory (CTIO), reports that preliminary photometry from
observations obtained by L. Strolger on May 17.1 with the CTIO
0.9-m telescope yields V = 14.56, B-V = 0.00.  Additional visual
magnitude estimates:  May 14.79, 14.8: (P. Marples, Loganholme,
Qld.); 15.7, 14.7 (Evans).

     J. Homan, P. G. Jonker, and M. van der Klis, Astronomical
Institute 'Anton Pannekoek', University of Amsterdam; and E.
Kuulkers, Space Research Organization Netherlands, Utrecht, and
Astronomical Institute, Utrecht University, report:  "The blackhole
candidate LMC X-3 was observed with the RXTE/PCA during May 13.894-
13.995 UT.  The 2-30-keV power spectrum of that observation reveals
strong variability, with a fractional rms amplitude of about 40
percent (0.01-100 Hz).  The shape of the power spectrum can be
characterized by a broken power law, with a break at 1.1 +/- 0.4 Hz.
In addition a quasiperiodic oscillation was found at 0.42 +/- 0.02
Hz, with a strength of 12 +/- 2 percent (3.7-sigma, single trial),
and a width of 0.10 +/- 0.04 Hz.  Spectral fits yield values
similar to those reported by Boyd and Smale (IAUC 7424).  This is
the first time that LMC X-3 has been found to show rapid time
variability similar to that of blackhole candidates in their
low/hard state.  Together with the spectral measurements, this
strongly suggests that LMC X-3 has entered such a low/hard state."

                      (C) Copyright 2000 CBAT
2000 May 17                    (7425)            Daniel W. E. Green

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