Central Bureau for Astronomical Telegrams
IAUC 3575: Vel X-1; 1979 J 1; 1979k
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Read IAUC 3576
Circular No. 3575
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM Telephone 617-864-5758
VELA X-1
M. Oda and the Hakucho Team, Institute of Space and Aeronautical
Science, University of Tokyo, telex: "Observations of the x-ray
pulsar Vela X-1 (= 4U 0900-40) with the Hakucho satellite indicate
a high rate of spin-down, as data obtained 1980 Dec.-1981 Jan. reveal
a pulse period of 282s.87 +/- 0s.O2 (preliminary). In 1979 Mar.,
the pulsar's heliocentric pulse period (282s.745 +/- 0s.006) was consistent
with its long-term trend of decreasing period of ~ 0.04 s/yr
(cf. Rappaport et al. 1980, Ap. J. 235, 570). However, by 1980 Mar.
the period had increased to 282s.7874 +/- 0s.0014. In view of this peculiar
behavior, optical data of its companion, HD 77581, are very
important. Spectroscopic data have not been published since those
given by Hutchings (1974, Ap.J. 192, 685); immediate spectroscopic
observations of HD 77581 are strongly urged. Those who have unpublished
spectroscopic data of this object are requested to contact N.
Oda, Institute of Space and Aeronautical Science, University of
Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, Japan (telex Japan 24550
SPACETKY J); or J. Jugaku, Tokyo Observatory, 2-21-1 Ohsawa, Mitaka
City, Tokyo, Japan."
1979 J 1
S. P. Synnott, Voyager Project, Jet Propulsion Laboratory, reports
that six observations of a satellite in transit across Jupiter
have been found in Voyager 1 frames over a total observing interval
of 43 hr, which yield an orbital period of 7h09m30s The
profile observable in transit is slightly elliptical and 15-20 km
across. The orbit predicts a position within 5o of the Voyager 2
discovery observations of 1979 J 1, although the error in this prediction
could be 50o. Because there appear to be no further observations,
it is unlikely that a more conclusive tie between the new
Voyager 1 transits and 1979 J 1 can be made from Voyager data alone.
The satellite 1979 J 3 was being occulted by Jupiter during the
times of these new observations.
PERIODIC COMET SCHWASSMANN-WACHMANN 2 (1979k)
Total visual magnitude estimates and coma diameters: Jan.
25.05 UT, 11.9, 1'.2 (J. Bortle, Stormville, NY, 0.32-m refl.); Feb.
6.10, 12.0, 0'.8 (C. S. Morris, Harvard, MA, 0.25-m refl.).
1981 February 18 (3575) Daniel W. E. Green
Read IAUC 3576
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