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THE ASTRONOMER Electronic Circular No 919       1995 Jan 29 11.17UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England. Telephone/FAX(0256)471074 Int:+44256471074
INTERNET: GMH at AST.STAR.RL.AC.UK  or    GMH at GXVG.AST.CAM.AC.UK
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SATURN
J. Lecacheux, Observatoire de Meudon; and A. Sanchez-Lavega, Bilbao
University, report:  "From CCD imaging of Saturn on 1994 Nov. 22.8
and Dec. 16.8-17.8 UT with the Pic du Midi 1-m telescope,
we derive a drift rate of +9.9 deg/day in longitude (system I) for
the bright yellowish equatorial disturbance observed by the Hubble
Space Telescope on Dec. 1. We have also recorded another major
bright feature, 135 deg eastward, with similar latitude and motion;
the wind velocity appears slower by 100 m/s than normally expected
at this latitude."
IAUC 6128

F. Colas, Bureau des Longitudes, Paris; E. Frappa, Planetarium
de Saint-Etienne; J. Gomez, G.E.A., Barcelona; P. Laques,
Observatoire du Pic du Midi; J. Lecacheux, Observatoire de Meudon,
DESPA; and M. Tagger, Service d'Astrophysique, Centre d'Etudes de
Saclay, report on recent observations at the Pic du Midi 1-m
telescope:  "During continuous CCD imaging of Saturn on 1994 Nov.
22.8 and Dec. 16.8-17.8 UT under very stable seeing conditions
(0".6), we convincingly detected several 'spokes' on the B ring
[see also Sheehan and O'Meara 1993, Sky Tel. 85(1), 20], the rings
being then inclined by 8 deg to our line-of-sight. Our best time
resolution was 4 images/min.  The reflectance contrast for the
features (spokes) in the rings was at maximum in the I band (855
nm), reaching 3 percent on our best images, but they were also
detected in R; from our 3.8-hr sequence on Dec. 17 (169 images),
their behavior was reminiscent of that detected by both Voyager
spacecraft, appearing on that part of the rings exiting the
saturnian shadow.  The spokes are observed close to the corotation
radius (where the keplerian frequency equals the rotation frequency
of Saturn and its magnetosphere), with some extension inwards and
outwards by +/- a few thousands of km.  The spokes vanished upon
arrival in front of the planet.  No significant detection was
obtained on the opposite half-ring.  The maximum activity was
observed when dawn occurred on the rings over 95-125 deg in
longitude (system III), consistent with the strong peak at 115 deg
observed from Voyager data (cf. Esposito et al. and Mendis et al.
1984, in Saturn, Univ. of Arizona Press).  Saturn is currently
nearing solar conjunction, and the current ring tilt is 5.7 deg; on
April 12, at a similar elongation after conjunction, the tilt will
be only 1.6 deg and the spokes difficult or impossible to image
through the ring-plane passages."
IAUC 6129

VW HYDRI
Jan Hers relays that Danie Overbeek, South Africa, has reported an
outburst of VW Hydri:
1995 Jan 24.9UT, [13.0; 25.844, 9.4

Guy M Hurst