-------------------------------------------------------------------
THE ASTRONOMER Electronic Circular No 1547      2000 Jly 29 14.51UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074
INTERNET: GUY@TAHQ.DEMON.CO.UK             GMH at AST.STAR.RL.AC.UK
WORLD WIDE WEB                    http://www.demon.co.uk/astronomer
-------------------------------------------------------------------
DELTA SCORPII
Sebastian Oterma of Buenos Aires, has reported a gradual increase
in brightness of delta Scorpii. On 2000 June 30.03, he estimated
it at magnitude 2.2v increasing to 2.0 by July 20.02. There are
suggestions that this is a Gamma Cas style outburst.

J. Fabregat, University of Valencia; and P. Reig, Foundation
for Research and Technology Hellas and University of Crete,
Heraklion, write:  "This star is undergoing a major optical and
H-alpha outburst.  Spectra (resolution 0.3 nm, range 580-760 nm)
taken with the Skinakas Observatory 1.3-m telescope reveal the
H-alpha line in emission.  Measured equivalent widths are -0.34 +/-
0.02 nm on July 19.89 UT and -0.33 +/- 0.02 nm (FWHM 0.69 +/- 0.01
nm) on July 20.90. In 1990, Cote and van Kerkwijk (1993, A.Ap. 274,
870) observed weak emission on the flanks of the H-alpha line core
in absorption, and they proposed the classification of delta Sco as
a Be star.  All other observations in the literature present a
normal absorption-line spectrum, while our observations constitute
the first detection of emission lines in delta Sco, confirming its
Be-star nature."
IAUC 7461

COMET C/2000 O1 (KOEHN)
B. W. Koehn, Lowell Observatory, has reported his discovery of a
possible comet in the course of the Lowell Observatory
Near-Earth-Object Survey:
     2000 UT             R.A. (2000) Decl.        m1    Observer
     July 20.36467    1 03 24.38   +39 53 01.6   17.6   Koehn
          22.07410    1 02 18.03   +39 59 08.6          Busch
          22.97988    1 01 41.57   +40 02 18.3   17.9   Ticha
          23.37434    1 01 25.93   +40 03 38.3          Robinson
B. W. Koehn (Lowell Observatory).  0.59-m LONEOS Schmidt.
Apparently a coma 10" in diameter and a 50" tail in p.a. 80 deg.

The following preliminary parabolic orbital elements, by Brian
Marsden, are from nine observations:
     T = 2001 Jan. 22.779 TT          Peri. =  94.670
                                      Node  =  93.310   2000.0
     q = 5.69793 AU                   Incl. = 148.855
IAUC 7462

Editor: The comet at present is believed fainter than mag 17
over the period until late August.

COMET C/1999 S4 (LINEAR)
Mark Kidger, Instituto de Astrofisica de Canarias, writes that
nightly observations made since July 23 in U, B, V, R, and Z
broadband filters with the 1-m Jacobus Kapteyn Telescope show what
appears to be the complete disruption of the comet's nucleus:  "The
central condensation was highly condensed and showed the typical
'teardrop' form on July 23.9 and 24.9 UT, although its brightness
decreased by a factor of about 3 between the two nights.  On July
25.9 the central condensation was seen to be strongly elongated
(length about 15") in p.a. 80 deg, with a very flat brightness
distribution.  The condensation's brightness faded further and its
length increased to about 30" and 45"-50" (p.a. 80 deg) on July
26.9 and 27.9, respectively.
IAUC 7467 (extract)
Guy M Hurst