Central Bureau for Astronomical Telegrams
IAUC 7129: S/1998 (45) 1; U Sco
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Circular No. 7129
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html ISSN 0081-0304
Phone 617-495-7244/7440/7444 (for emergency use only)
S/1998 (45) 1
W. J. Merline, Southwest Research Institute, Boulder, reports
for a large collaboration (including L. M. Close, C. Dumas, C. R.
Chapman, F. Roddier, F. Menard, D. C. Slater, G. Duvert, C.
Shelton, and T. Morgan) the discovery of a satellite of (45)
Eugenia on 1998 Nov. 1.5 UT from H-, J-, and K'-band direct imaging
with the 3.6-m Canada-France-Hawaii Telescope (+ PUEO adaptive-
optics system) on Mauna Kea. The satellite is about 6 mag fainter
than (45) and was tracked intermittently on five nights over a
10-day span. Merline et al. derive a near-circular orbit with a
period of about 4.7 days, inclined to the line-of-sight by about 45
deg, with a maximum elongation of about 0".8. The satellite was
recovered with the CFHT on 1999 Jan. 4. An occultation around Mar.
27.13 of the star CMC 804951 (mag 11.9) by (45) was predicted by
D. W. Dunham, but this is likely to be visible only near the
earth's north-polar regions (see updates at
http://members.home.net/dega/astchart.htm).
U SCORPII
P. Bonifacio, P. Molaro, and P. Selvelli, Astronomical
Observatory, Trieste, write: "Spectra (range 400-665 nm, resolution
0.34 nm), obtained on Mar. 16.4 and 17.4 UT with the ESO 3.5-m New
Technology Telescope (+ EMMI spectrograph), show composite structure
in the hydrogen emission lines. The central component falls at the
rest wavelength, with the two satellite emissions shifted by
velocities of +1580 and -1760 km/s (as measured in H-alpha); all
three components are well resolved (FWHM 600 km/s). The two
emissions on either side of H-alpha are not attributable to [N II]
(654.8 and 658.4 nm), since the triplet-like structure is seen in
the other Balmer lines observable in our spectra (up to H-delta).
A similar structure is present also in the He II (454.2, 468.6,
541.3 nm) emission lines. Two otherwise unidentified emission
lines at 584.4 and 590.8 nm are likely the symmetrically displaced
components of the He I 587.6-nm line, whose central component is
absent. Such peculiar structure in both the H and He recombination
lines was not reported at the 1979 and 1987 outbursts. The H-alpha
FWZI is 5600 km/s, showing a decrement from the value reported on
IAUC 7118. The relative emission intensities of the line
components changed between the two nights, with a strengthening of
the central one. The 464.0-nm complex is present as a wide and
unresolved blend. Narrow emissions of O I (the nebular 630.0- and
636.3-nm and the auroral O I 557.7-nm transitions) are present,
marking the onset of the nebular phase."
(C) Copyright 1999 CBAT
1999 March 20 (7129) Daniel W. E. Green
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