Central Bureau for Astronomical Telegrams
IAUC 8970: R/2006 S 5, R/2007 S 1; P/2008 Q4
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Circular No. 8970
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
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Phone 617-495-7440/7244/7444 (for emergency use only)
R/2006 S 5 AND R/2007 S 1
C. C. Porco, CICLOPS, Space Science Institute, Boulder, on
behalf of the Cassini Imaging Team, reports the detection of a ring
arc (designated R/2007 S 1) associated with the small satellite
Saturn XLIX (Anthe; semi-major axis 197655 km; cf. IAUCs 8857, 8873),
and the apparent confirmation of a previously reported ring arc
R/2006 S 5 (IAUC 8773) associated with the satellite Saturn XXXII
(Methone; semi-major axis 194230 km; IAUCs 8389, 8471). The ring
arc in the orbit of Anthe was detected in a series of five 15-s-
exposure recovery images of Anthe taken with the Narrow Angle
Camera of the Cassini Imaging Science Subsystem on 2007 Oct. 29 at
a phase angle of 23 deg. The satellite appears to be embedded in
the arc but is drifting slowly with respect to it. The Anthe arc
extends over about 20 deg in longitude and appears to be associated
with material trapped in the 11:10 co-rotation eccentricity
resonance with Saturn I (Mimas). Furthermore, additional
detections of the Anthe arc between 2008 February and July show
that the satellite's motion with respect to the arc is consistent
with Anthe's +/- 7 deg libration in the same 11:10 resonance,
suggesting that Anthe is the likely source of the arc material, and
also that it may be creating structure within the arc. The
earliest detection of the Anthe arc was on 2007 June 15.
Serendipitously, the discovery image of the Anthe arc also revealed
that the satellite Methone is embedded in an arc of material with a
longitudinal extent of about 10 deg, which may be associated with
the 15:14 corotation eccentricity resonance with Mimas. Additional
detections of the arc were made in 2008 Feb.-Apr.; the earliest
detection was on 2007 May 31. The observed Methone arc could help
to explain data from the LEMMS sensor of the Cassini Magnetospheric
Imaging Instrument that led to the detection of R/2006 S 5 (IAUC
8773).
COMET P/2008 Q4 (LONEOS)
M. Jaeger, Stixendorf, Austria, reports his recovery of comet
P/2001 R1 (cf. IAUC 7713) with a small coma (< 20") and a 3' tail
in p.a. 275 deg on CCD images taken with a 0.20-m reflector;
astrometry by W. Vollmann:
2008 UT R.A. (2000) Decl. Mag.
Aug. 31.08719 7 39 31.16 +25 12 23.9 16.5
New astrometry, revised orbital elements (the indicated correction
to the prediction on MPC 54169 is Delta(T) = -0.42 day), and an
ephemeris appear on MPEC 2008-R09.
(C) Copyright 2008 CBAT
2008 September 5 (8970) Daniel W. E. Green
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