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IAUC 7900: Sats OF JUPITER; XTE J0929-314; C/2002 C1

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                                                  Circular No. 7900
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)

     MPEC 2002-J54 provides 109 observations of 11 new outer
satellites of Jupiter.  Following the communication to the Minor
Planet Center by S. S. Sheppard and D. C. Jewitt, University of
Hawaii, and J. Kleyna, University of Cambridge, of CCD observations
with the 3.6-m Canada-France-Hawaii and 2.2-m University of Hawaii
telescopes on pairs of nights in Dec. 2001 (Dec. 9-11 and 17-19),
B. G. Marsden considered these 11 objects (in the mag range R =
22.2-23.5) likely to be satellites and provided ephemerides that
allowed Sheppard's measurement of further images on 2002 Jan. 8, as
well as generally on another night during Jan. 9-16 and, with the
help also of orbit calculations by R. Jacobson, Jet Propulsion
Laboratory, during Feb. 10-11.  In two cases Sheppard identified
and measured images on Mar. 12.  Marsden's final perturbed orbit
solutions (epoch 2002 May 6.0 TT), also given on MPEC 2002-J54,
show all the satellites, designated S/2001 J~1-J 11, to have
retrograde orbits (140 deg < i < 166 deg to the 2000.0 ecliptic)
with P in the range 557-773 days and H from 15.4 to 16.8.

XTE J0929-314
     D. K. Galloway, E. H. Morgan, R. A. Remillard and D.
Chakrabarty, Massachusetts Institute of Technology, report:  "We
have computed provisional orbital elements for XTE J0929-314 (cf.
IAUC 7897), using pulse frequency measurements from RXTE/PCA
observations between May 2.54 and 13.83 UT.  Assuming a constant
pulsar spin frequency and a circular orbit, our preliminary orbital
solution has binary period 2614.75(15) s, projected semimajor axis
6.1(3) light-ms, and orbital epoch (time of 90 deg mean longitude)
2002 May 11.4941(2) UT at the solar-system barycenter.  The derived
barycentric pulsar spin frequency is 185.1052(1) Hz.  The inferred
mass function of 2.7 x 10**-7 solar mass is the smallest measured
for any stellar binary.  For a 1.4-solar-mass neutron star, the
minimum companion mass is 0.008 solar mass (or 8.5 Jupiter masses).
The x-ray source was active at a flux of 13 mCrab (2-10 keV) on May
15.69.  RXTE observations are continuing."

     Visual m_1 estimates:  Apr. 28.85 UT, 4.4 (W. Hasubick,
Buchloe, Germany, 10x50 binoculars); May 1.92, 4.8 (R. J. Bouma,
Groningen, The Netherlands, 7x50 binoculars); 6.98, 5.0 (A.
Kammerer, Ettlingen, Germany, 9x63 binoculars); 11.24, 4.9 (A.
Hale, Cloudcroft, NM, naked eye); 16.18, 5.1 (D. W. E. Green, Pack
Monadnock Mtn., NH, naked eye).

                      (C) Copyright 2002 CBAT
2002 May 16                    (7900)            Daniel W. E. Green

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