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IAUC 3040: Occn OF SAO 158687 BY URANUS ON 1977 Mar. 10; Occn OF gamma Cet BY (6)

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                                                  Circular No. 3040
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Cable Address: SATELLITES, NEWYORK     Telex: 921428
Telephone: (617) 864-5758

     G. E. Taylor, H.M. Nautical Almanac Office, provides the
following predicted local circumstances, derived from the observations
on IAUC 3038 but assuming a radius of 27 000 km for Uranus:

Station            Disappearance            Appearance
                UT    P    h*    hs      UT    P    h*    hs
Perth          20h8  355o  67o  -18o    21h3   40o  62o  -12o
Johannesburg   20.9  344   24   -53     21.6   50   33   -58

h* and hs represent the altitudes of the star and the sun, respectively.
It should also be noted, however, that observations with
astrographs at both the Perth and Sydney Observatories indicate
that no occultation will be observable from anywhere on the earth.

     P. K. Seidelmann and T. C. Van Flandern, U.S. Nautical Almanac
Office, report that complete reduction of the transit-circle observations
(IAUC 3038) confirms that the SAO position of the star requires
correction by +1".15 +/- 0".10 in Decl.; reduction of observations
of the lunar occultation on Feb. 10 yields a similar result, if it
is assumed that the correction in R.A. is negligible.  Transit-circle
observations of Uranus confirm that the A.E. position of the planet
requires correction by -0".22 in Decl.

     Computations by the undersigned suggest that, all things
considered, prospects of an occultation are very good for southern
Africa and fairly good for southwestern Australia.

     G. E. Taylor has also predicted that gamma Cet A (magnitude 3.6)
will be occulted by (6) Hebe for observers in Mexico on Mar. 5.
The occultation track will be some 200 km wide and the maximum duration
5s.  An occultation of gamma Cet B (magnitude 7.4) will occur in
the southeastern Pacific Ocean.  D. W. Dunham, Computer Sciences
Corporation, has refined the prediction using astrometric observations
made by R. S. Harrington at the U.S. Naval Observatory on Feb.
17.0 UT.  He finds that the nominal central line passes some 150 km
north of Mexico City and across northern Cuba, although the uncertainty
is such that the track could be shifted to Baja California
and the U.S. Gulf Coast or to Nicaragua and possibly even northern
Venezuela.  The event will occur around 2h32m-2h33m UT.

1977 February 23               (3040)              Brian G. Marsden

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