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IAUC 3644: 1981 VA; PSR 0833-45; Q0957+561A, B

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                                                  Circular No. 3644
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


1981 VA
     J. Williams, California Institute of Technology, reports that
E. Helin and S. Dunbar have discovered a fast-moving asteroidal
object with the l.2-m Schmidt telescope at Palomar, as follows:

     1981 UT          R. A. (1950) Decl.      Mag.
     Nov.  4.31979    2 55.2     +56 38       16.5
           5.40104    2 51.0     +54 20
           5.48438    2 50.8     +54 10


PSR 0833-45
     P. M. McCulloch, P. A. Hamilton, and G. W. R. Royle, University
of Tasmania; and R. N. Manchester, Division of Radiophysics,
CSIRO, telex: "We observed an abrupt decrease in the period of the
Vela pulsar, PSR 0833-45, at Oct. 11d01h40m UT.  The fractional
change at that time in pulse frequency was 1.144 (+/- 0.003) x 10**-6
and in frequency derivative was 0.018 +/- 0.003.  These results were
derived from 2295-MHz observations made at ~ weekly intervals at
the NASA Deep Space Station, Tidbinbilla, from July 9 to Oct. 14,
and from daily 635-MHz observations of 5-hr duration at Hobart from
Oct. 8-14.  As the actual jump was not observed, its epoch was
computed by assuming no discontinuity in pulse phase at time of jump.
Though smaller, this jump is similar to those observed previously."


Q0957+561A, B
     M. V. Gorenstein, I. I. Shapiro, A. F. F. Rogers and N. L.
Cohen, Massachusetts Institute of Technology and Haystack Observatory,
write: "We have detected a third compact radio component
smaller than 0".003 in extent from 13-cm VLBI observations of the
gravitational 'lens' system Q0957+561.  The component, 0".181 east
and 1".029 north of the B quasar (equinox 1950.0, +/- 0".001), is near
or at the center of the elliptical galaxy thought to be mainly
responsible for the multiple imaging.  This detection utilized the
Mark III VLBI system and the large antennas at Effelsberg, Goldstone
and Madrid on Mar. 15-16.  Data from the Goldstone-Madrid
baseline (0".0035 fringe-spacing) and from the Bonn-Madrid baseline
(0".020 fringe-spacing) yielded flux densities of 600 +/- 90 and 1700
+/- 150 uJy, respectively.  The component could be either the radio
core of the galaxy, another image of the quasar or some
combination."


1981 November 6                (3644)              Daniel W. E. Green

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