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IAUC 4327: 1987A

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                                                  Circular No. 4327
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM    Telephone 617-495-7244/7440/7444

     G. L. White, CSIRO Australia; and D. F. Malin, Anglo-Australian
Observatory, communicate: "The proposed progenitor is seen as
two overlapping images on a plate taken on 1984 Feb. 5 using the
prime-focus triplet corrector of the AAT.  Astrometry from a series
of short-exposure plates obtained on 1987 Feb. 27.4 UT by S. Lee
using the same instrument and similar emulsions and filters
confirms that the brighter (star 1, south following) object is in
excellent positional coincidence with the supernova.  The differences
SN - star 1 are in R.A. = -0".04 +/- 0".09, in Decl. = -0".03 +/- 0".10,
considerably strengthening the proposed identification.  The absolute
position of the supernova was determined to be  R.A.  =  5h35m49s.95  +/-
0s.039, Decl. = -69 17'57".9 +/- 0".27 (equinox 1950.0, Perth 70 system)."
     C. Gry, A. Cassatella, W. Wamsteker and L. Sanz, ESA IUE
Observatory; and N. Panagia, Space Telescope Science Institute, for
the IUE SN Team, report: "Continued observations have shown that
the very rapid decrease in the far ultraviolet, which was occurring,
at 132.5 nm, at a rate of about 0.1 mag/hr during Feb. 25-27,
has stopped completely.  On Mar. 2.29 UT the spectrum between 115
and 160 nm was very similar to that of a B supergiant in the LMC.
This indicates that in the ultraviolet we are again starting to
see Sanduleak -69 202.  At longer wavelengths the rate of decrease
still appears to be more or less constant: 0.03 mag/hr at 295 nm
with no indications of any slowing down.  A short reversal seems
to have occurred during Feb. 26.21-26.37 UT; this appears to be
associated with the broad peak in the spectrum at 292.5 nm only.
The details of the spectral appearance are still changing rapidly
in the wavelength interval 260-320 nm, with new peaks around 302.4
and 316.4 nm.  The fine-error-sensor magnitudes indicate that the
supernova passed through its maximum on Feb. 27.  Preliminary
inspection of the high resolution spectra has confirmed the presence
of many interstellar lines, including weak lines such as Ni II and
Zn II.  This is the second time that interstellar Ni has been
identified in an external galaxy.  Most elements show stronger
interstellar lines in LMC-associated material than in our own Galaxy".
     Further visual magnitude estimates: Feb. 27.74 UT, 4.3 (J.
Campos, Durban, R.S.A.); 28.47, 4.2 (T. Beresford, Adelaide, South
Australia); 28.84, 4.4 (Campos); Mar. 1.43, 4.2 (Beresford); 1.76,
4.5 (Campos); 1.88, 4.5 (Campos); 2.44, 4.2 (Beresford).

1987 March 2                   (4327)              Brian G. Marsden

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