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IAUC 4553: 1988d; T Pyx; 1987g

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                                                  Circular No. 4553
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM    Telephone 617-495-7244/7440/7444

     Malcolm Hartley reports his discovery of a comet on plates
exposed with the U.K. Schmidt Telescope at Siding Spring.  The object
appears weak on the Feb. 19 I plate and exhibits an obvious 10'
tail in p.a. 305 deg on the Feb. 22 J plate.  Both images are near the
edges of the plates.  Measurements by R. H. McNaught:

       1988 UT              R. A.  (1950)  Decl.         m1
       Feb. 19.58883     10 12 16.57    - 3 00 46.4     16.5
            19.65133     10 12 14.30    - 3 00 44.9
            22.50434     10 09 52.49    - 2 56 20.5
            22.57219     10 09 49.64    - 2 56 14.4

     R. H. McNaught, Siding Spring Observatory, reports that his
observations on Feb. 20.44, 21.49, and 22.60 UT, and observations
by T. Cragg and RASNZ observers (reported via F. Bateson), show no
change from the normal minimum magnitude of about 15 (cf. IAUC 4551).
The star is marginally (0.1-0.2 mag) brighter than during 1985-86.

     Z. Sekanina, Jet Propulsion Laboratory, California Institute
of Technology, reports:  "My recent determination of the rotation
pole of P/Tempel 2 (Sekanina 1987, ESA SP-278, p. 323) indicates
that the earth is currently located within 10 deg of the comet's
equatorial plane and that this aspect will continue until early Aug.
Comparison of this rotational model with photometric observations
by Jewitt and Meech (1988, Ap.J., in press) in 1987 Mar.-Apr.
suggests that the nucleus is strongly elongated perpendicular to its
spin axis, implying a large rotation-induced brightness amplitude
near the earth's transit across the equatorial plane.  Attention is
called to currently-favorable conditions (ephemeris on MPC 12329)
for detecting large brightness variations due to nuclear rotation,
although interference from occasional flare-ups is possible from
1987 Nov. on.  These conditions should persist until the comet
becomes too active for nucleus monitoring, probably in 1988 May-June.
During another near-transit window, in 1989 Apr., the comet will be
near conjunction with the sun."

1988 February 23               (4553)            Daniel W. E. Green

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