Central Bureau for Astronomical Telegrams

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IAUC 8524: S/2005 S 1; V2361 Cyg; C/1998 U7

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IAUC number

                                                  Circular No. 8524
Central Bureau for Astronomical Telegrams
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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S/2005 S 1
     C. C. Porco, CICLOPS, Space Science Institute, Boulder; and
the Cassini Imaging Science Team report the discovery of a new
satellite of Saturn, designated S/2005 S 1, orbiting within the
Keeler gap in Saturn's outer A ring.  (The object had been
previously inferred from the presence of features observed on the
outer edge of the Keeler gap; cf. Porco et al. 2005, Science 307,
1226, Fig. 10).  The object was discovered in six images taken
over 16 min on May 1 from a time-lapse sequence of 0.180-s narrow-
angle-camera exposures that were targeted to the illuminated side
of the outer edge of the A ring (with phase angle about 33 deg and
image scale 6.9 km/pixel).  S/2005 S 1 was subsequently found in 32
(7 km/pixel) low-phase images taken of the F ring on Apr. 13
(spanning 18 min) and again in two high-resolution (3.54 km/pixel)
low-phase images taken on May 2, when its 7-km disk was resolved.
The satellite orbits Saturn every 0.594 day at a distance of 136500
km.  The estimated geometric albedo is 0.5.  The data are too
coarse to yield any statistically significant orbital eccentricity
or inclination.

     R. W. Russell, R. J. Rudy, and D. K. Lynch, Aerospace
Corporation; and W. Golisch, Infrared Telescope Facility (IRTF),
report on a 0.8-2.5-micron spectrogram taken of V2361 Cyg (cf. IAUC
8483) with the IRTF (+ SpeX) on Mar. 6.66 UT.  The calibrator was
HD 192538 (an A0 star with mag V about 6.5).  The most prominent
aspect of the spectrum was a strong, smooth continuum rising toward
longer wavelengths across the entire spectral range -- indicative
of thermal emission from dust -- and the continuum was well-fitted
by a 970-K (+/- 10 K) blackbody.  Also present in the spectrum were
the following doubled emission lines (2600 km/s FWHM) with
prominent red components:  He I 1.0830-microns, H I 1.2818-microns,
and O I at 0.8446, 1.1287, and 1.3165 microns.  H I Paschen_gamma
was present but very weak and blended with He I.  The reddening, as
determined from the O I lines, was E(B-V) about 1.2 mag, a
significant fraction of which may be local to the source.

COMET C/1998 U7 (SOHO)
     Another faint Kreutz sungrazer, stellar in appearance (cf.
IAUC 8519):

 Comet       1998 UT       R.A.(2000)Decl.  Inst.  F    MPEC
 C/1998 U7   Oct. 26.979   13 53.4  -15 29   C3    XL   2005-H24

                      (C) Copyright 2005 CBAT
2005 May 6                     (8524)            Daniel W. E. Green

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