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IAUC 7757: (90); 1987A

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                                                  Circular No. 7757
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 617-495-7440/7244/7444 (for emergency use only)

     T. Michalowski, T. Kwiatkowski, and A. Kryszczynska, Poznan
Astronomical Observatory; F. Colas, L'Institut de Mecanique Celeste
et de Calcul des Ephemerides, Paris; and J. Michalowski, Poznan
University of Technology, write:  "CCD observations of the binary
minor planet (90) Antiope (cf. IAUC 7503), carried out at Borowiec
Observatory and at Pic du Midi on seven nights between Oct. 19 and
Nov. 15, show a two-component lightcurve with each showing the same
period of 16.496 hr.  The first component (with amplitude 0.10 mag)
is associated with the rotation of two non-spherical bodies of the
system; the second one, showing two sharp minima (with amplitude
0.12 mag), is due to mutual occultation/eclipse events in the
binary system.  The lightcurve suggests that the rotational periods
of both bodies are equal to the orbital period, which is
characteristic for synchronous rotation.  The amplitude of the
existing occultation/eclipse is much larger than predicted earlier
by Michalowski et al. (2001, A.Ap. 378, L14), which suggests that
the bodies are larger than previously thought and/or that the
orbital plane of the system precesses.  New observations will help
to improve a model of the binary minor planet."

     R. N. Manchester, Australia Telescope National Facility; and
B. M. Gaensler, Harvard-Smithsonian Center for Astrophysics, report
on behalf of a larger collaboration:  "We have observed SN 1987A
with the newly installed 12-mm receivers on the Australia Telescope
Compact Array.  In a 12-hr observation beginning Oct. 26.59 UT, we
detected the supernova remnant at a high significance level.  Its
position is consistent with previous radio observations (Gaensler
et al. 1997, Ap.J. 479, 845; Manchester et al. 2001, Pub. Astron.
Soc. Australia, in press).  The observed flux densities were 20 +/-
1 and 18 +/- 1 mJy at 17.0 and 18.9 GHz, respectively.  These
measurements are marginally above extrapolations of the power-law
spectrum previously seen between 0.8 GHz and 9 GHz.  The source is
slightly extended at our available spatial resolution (2".8 x 1".8).
Modeling the data as a thin spherical shell yields a diameter of
1".6 +/- 0".1, consistent with the slow expansion speed inferred
from lower frequency measurements.  Further 12-mm observations at
higher resolution will be carried out later this year."

                      (C) Copyright 2001 CBAT
2001 November 20               (7757)            Daniel W. E. Green

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