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IAUC 3457: SATURN

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                                                  Circular No. 3457
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


SATURN
     D. Cruikshank, University of Hawaii, reports the observation
of a satellite, designated 1980 S 3, near greatest western elongation
on Feb. 26.54 UT.  Vidicon images were recorded over a 2-hr
interval with the 2.2-m reflector.  The object was estimated at mv
~ 15.5,  fainter than Saturn VII (Hyperion) nearby.  A marginal
image was also recorded of a satellite, designated 1980 S 4, near
greatest eastern elongation around Feb. 27.6 UT.

     Further to the note on IAUC 3456, B. A. Smith, Lunar and
Planetary Laboratory, confirms that 1966 S 2 = 1979 S 1 = 1979 S 2
= 1979 S 7 = 1980 S 1 = 1980 S 2 and that the revolution period os
16h38m.4.  The same object was also recorded by Smith, H. J. Reitsema
and S. M. Larson with the 1.5-m reflector and CCD at greatest western
elongation on Mar. 1.34 UT, and an image could then be clearly
identified on an exposure obtained on Feb. 5.38 UT, when the
satellite was again at greatest western elongation.  For the true
(antedated by the light time) time of greatest eastern elongation Smith
gives the formula: 1980 Mar. 1.64 UT + 0.69335 E.  The number of
revolutions made by the satellite since 1966 is still uncertain by
1 or 2.  Smith, Reitsema and Larson also report the observation of
another possible satellite, designated 1980 S 5, near the eastern
end of the rings on Mar. 1.34 UT; it was somewhat fainter than
1966 S 2.

     P. Laques, Pic du Midi Observatory; and J. Lecacheux, Meudon
Observatory, report the detection of a fainter, more distant, object,
designated 1980 S 6, on exposures using the Pic du Midi 1.05-m
reflector and a Lallemand-type electronographic camera.  Measured
distances east of the center of Saturn along the line of the rings
were: Mar. 1.029 UT, 62".2; 1.049, 61".8; 1.099, 59".7; 1.131, 58".5:.
The magnitude was about 18.  They add: "A faint continuous exterior
ring extending symmetrically westward and eastward to more than
five equatorial radii was clearly detected on exposures ranging
from 40 to 130-s duration on G-5 and K-S emulsions, in B or V bands
or without filter; the images of stars or faint satellites on the
plates have diameter 1".  This exterior ring appears structureless,
and its brightness is estimated at ~ mag 18 per linear arcsec.  The
extension up to 7 radii recently reported by A. Dollfus (IAUC 3454)
is not confirmed."


1980 March 6                   (3457)              Brian G. Marsden

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