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IAUC 3466: Prob. Occn BY 1978 P 1; Sats OF SATURN; STEPANYAN'S STAR

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IAUC number

                                                  Circular No. 3466
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 617-864-5758

     A. R. Walker, South African Astronomical Observatory, reports
the observation, with the University of Cape Town's photometer on
the 1-m telescope at Sutherland, of an occultation of the mag ~ 12
star at R.A. = 13h40m45s.1, Decl. = +8o34'48" (equinox 1950.0).  The event
had a duration of 50s and was centered on Apr. 6d23h39m28s UT.  The
event was apparently caused by Pluto's probable satellite, 1978 P 1
(cf. IAUC 3464), which is deduced therefore to have a minimum
diameter of 1200 km.  Positive or negative reports from other
observers would be very useful.

     H. J. Reitsema, Lunar and Planetary Laboratory, reports that
observations by P. A. Smith, S. M. Larson and himself with the
1.5-m reflector appear to confirm the objects 1980 S 7 and 1980 S 8,
described by Harris and Gibson on IAUC 3463, but there was no obvious
detection of 1980 S 9; the approximate separations from the
center of Saturn were: 1980 S 7, Mar. 13.35 UT, 17" east and moving
in; 1980 S 8, Mar. 15.19, ~ 19" east.  Another probable satellite,
designated 1980 S 11, was detected some 22" east of Saturn's center
on Mar. 14.47 UT, and this object has been confirmed by Harris at
Mount Wilson Observatory.  With reference to the notes by Laques
and Lecacheux on IAUC 3457 and by Lamy and Mauron on IAUC 3463,
Reitsema reports the following separations of an object, designated
1980 S 12, detected well to the east of the center of Saturn: Mar.
28.2125 UT, 56".5; 28.2451, 57".9; 28.2692, 59".0; 28.2927, 60".2;
28.3153, 61".7; the object is in the plane of the rings and of mag
17.  Further, two of these more distant objects were observed
simultaneously on Apr. 8: 1980 S 13, of mag ~ 17.5, moved from 43" west
of Saturn on Apr. 8.32 to 41" west on Apr. 8.35; 1980 S 14, of mag
17.3, was located 55" east of Saturn on Apr. 8.15 and attained a
greatest eastern elongation of 61" during Apr. 8.26-8.35 UT.

     Further to the notes on IAUC 3462 and 3465, K. Horne, California
Institute of Technology; B. Margon, University of California at
Los Angeles; and J. Africano, Sacramento Peak Observatory, write
that observations of six further eclipses in 1980 Mar. refine the
period to 3h48m08s.3 +/- 0s.5.  The epoch remains at HJD 2444293.0243.

1980 April 10                  (3466)              Brian G. Marsden

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