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IAUC 7197: C/1999 L1; XTE J1550-564; V382 Vel

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IAUC number

                                                  Circular No. 7197
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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COMET C/1999 L1 (SOHO)
     D. A. Biesecker, SM&A Corporation and Goddard Space Flight
Center, reports observations of another apparent Kreutz sungrazing
comet that he discovered in images taken with the C2 and C3
coronagraphs aboard SOHO.  No tail was evident.  Astrometric
measurements made by Biesecker (and reduced by G. V. Williams),
together with orbital elements by B. G. Marsden, are given on MPEC

     1999 UT            R.A. (2000) Decl.
     June 5.013        4 51.1       +19 40

XTE J1550-564
     M. Buxton, Research School of Astronomy and Astrophysics,
Australian National University; and S. Vennes, D. Wickramasinghe,
and L. Ferrario, Astrophysical Theory Centre, Australian National
University, write:  "We have obtained optical spectroscopy of the
blackhole candidate XTE J1550-564 during 1999 using the Anglo-
Australian Telescope on Apr. 13 and 14, and the 2.3-m telescope at
Siding Spring on Mar. 11, 24-27, and May 11.  We have measured the
equivalent width of H-alpha with the following results:  Mar.
11.67-11.75 UT, EW = -1.72 +/- 0.02 nm; 24.59-24.76, -1.56 +/- 0.09
nm; 25.57-25.68, -1.38 +/- 0.03 nm; 26.59-26.63, -1.84 +/- 0.20 nm;
27.61-27.65, -1.91 +/- 0.10 nm; Apr. 13.50-13.69, -2.41 +/- 0.09
nm; 14.49-14.72, -2.48 +/- 0.18 nm; May 11.48-11.70, -3.49 +/- 0.07
nm.  We clearly detect H-alpha emission in all spectra, together
with He I 587.5-nm and sometimes the Paschen series, but no H-beta,
He II, or Bowen blend is evident.  The interstellar lines at Na D
and 628.4 nm are also present.  These spectra contradict the result
of Soria and Wu (IAUC 7184), in that our data, which bracket their
spectrum taken at the AAT on Apr. 10, show H-alpha in emission and
not absorption; therefore we do not confirm detection of the
secondary.  We also find that the continuum steadily decreases over
time and, as a consequence, the EW of H-alpha increases.  The
decreasing continuum corresponds to the decrease of optical
emission as reported by Jain et al. (IAUC 7114, 7187)."

     Corrigendum.  On IAUC 7196, line 10, for  1.9 x 10**33  read
4.8 x 10**33

                      (C) Copyright 1999 CBAT
1999 June 11                   (7197)            Daniel W. E. Green

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