CBET 1263OCCULTATIONS BY (90) ANTIOPE AND BY S/2000 (90) 1
T. Hayamizu, Satsumasendai, Japan; M. Soma, Mitaka, Japan; and D. Herald,
Canberra, Australia, all of the International Occultation Timing Association,
report a successful observation in Japan of an occultation of the star TYC
1895-01450-1 by (90) Antiope and its satellite, S/2000 (90) 1 [cf. IAUC 7503],
on Jan. 2d17h42m UT. The observation followed from a prediction by S. Preston
(Seattle, WA, USA) for a 'single' object, supplemented by a prediction of
the relative positions of (90) and its satellite by J. Berthier (Institut de
Mecanique Celeste et de Calcul des Ephemerides) and J. Lecacheux (Laboratoire
d'Etude Spatiale et d'Instrumentation en Astrophysique), Centre Nationale de
la Recherche Scientifique, Paris Observatory, using the elements from
Descamps et al. (2007, Icarus 187, 482). The occultation by component 'A'
was observed by M. Owada (Hamamatsu, Japan). The occultation by component
'B' was recorded via video by K. Kitazaki (Musashino), M. Yanagisawa and Y.
Shimokawa (Chofu), M. Urabe (Kamogawa), T. Ohkawa et al. (Kawasaki), Y.
Hirose (Chigasaki), and S. Uchiyama (Sodegaura).
The best-fit ellipse to the observed chords of the occultation by
component B has dimensions of 89.2 +/- 4.2 x 81.9 +/- 0.8 km, with the
position angle of the major axis being 1.0 +/- 5.8 degrees. If the ellipse
is constrained to be aligned with component A, the ellipse dimensions are
82.0 +/- 0.9 x 80.8 +/- 0.9 km in p.a. 319 deg. This compares with the
values derived by Descamps et al. of 89.4 x 82.8 x 79.6 km. The predicted
separation and p.a. at the time of the occultation was 0".082 in p.a. 327 deg.
As there was only one chord observed for component A, the diameter of that
body cannot be determined from the occultation. However, 'miss' observations
by Y. Ohkita et al. (Kusatsu) and M. Ishida (Koka) constrain its location and
size. Assuming that component A is approximately the same size and
orientation as component B, the objects were separated by 0".0697 in p.a.
322.8 deg. If component A is assumed to be circular, with a diameter equal
to the maximum diameter from Descamps et al. of 93 km, the objects were
separated by 0".0666 in p.a. 320.3 deg. It is expected that the actual
separation and position angle is between these two values.
Other 'miss' observations were reported by R. Aikawa (Sakado), K.
Kageyama (Kumamoto), T. Hayamizu (Satsumasendai), N. Tatsumi (Akaiwa), A.
Hashimoto (Chichibu), A. Yaeza (Hitachi), H. Takashima et al. (Kashiwa),
M. Uchiyama (Owase), H. Yoshihara (Soja), M. Ida (Tsu), N. Sasanuma
(Toshima-ku), H. Tomioka (Hitachi), S. Uehara (Tsukuba), H. Karasaki
(Nerima-ku), and H. Hamanowa et al. (Koriyama).
NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
superseded by text appearing later in the printed IAU Circulars.
2008 February 17 (CBET 1263) Daniel W. E. Green
