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IAUC 7202: 1999cn; XTE J1550-564; V854 Cen

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IAUC number

                                                  Circular No. 7202
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
Phone 617-495-7244/7440/7444 (for emergency use only)

SUPERNOVA 1999cn IN MCG +2-38-043
     S. Benetti, Telescopio Nazionale Galileo (TNG); C. Morossi,
Osservatorio Astronomico di Trieste; and F. Bortoletto, R.
Cosentino, D. Gardiol, A. Ghedina, F. Ghinassi, A. Magazzu, E.
Marchetti, C. Pernechele, and A. Zacchei, TNG, report the discovery
of a supernova (V about 17.9) on a V CCD frame taken with the TNG
(+ Optical Imager Galileo) at La Palma on June 14.99 UT, while
observing the galaxy MCG +2-38-043 (CGCG 077-007; R.A. =
15h06m46s.6, Decl. = +12o51'29", equinox 2000.0).  SN 1999cn is
located on a spiral arm and its offset from the galaxy center is
1".5 west and 8".3 north.  Benetti also reports that an inspection
of a preliminarily reduced spectrum (range 328-760 nm; resolution
0.35 nm) taken at the William Herschel Telescope (+ ISIS) by D.
Axon, University of Hertfordshire; C. Packham, A. Humphrey, and J.
Ray, Isaac Newton Group; and J. Smith, University of Hertfordshire,
on June 15.14 shows that the supernova is of type Ic near maximum.
The spectrum is dominated by strong P-Cyg lines of Ca II (H and K)
and Fe II.  A weaker Si II 635.5-nm line is also visible.  The
expansion velocities as derived from Ca II and Si II lines are
about 13 900 and about 11 300 km/s, respectively.  The redshift of
the galaxy, derived from a strong and narrow H-alpha emission
superimposed on the supernova spectrum, is about 6790 km/s.

XTE J1550-564
     Correcting their report on IAUC 7184, R. Soria and K. Wu write:
"The G-star spectrum that was provided by the Anglo-Australian
Observatory through a service observation on Apr. 10 is not the
spectrum of the secondary star of RXTE J1550-564.  Therefore, the
spectral type and distance estimate based on this spectroscopic
observation are invalid."

     This R CrB-type variable has undergone a rapid fading, as
indicated by the following visual magnitude estimates:  June 4.56
UT, 7.8 (P. Williams, Heathcote, N.S.W.); 6.35, 8.0 (Williams);
6.98, 8.0 (A. Pereira, Cabo da Roca, Portugal); 7.38, 8.6
(Williams); 7.94, 8.3 (Pereira); 11.47, 10.9 (Williams); 13.44,
11.9 (Williams).

                      (C) Copyright 1999 CBAT
1999 June 15                   (7202)            Daniel W. E. Green

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