New Satellite of Neptune S/2003 N1

Figure 1: Discovery images of the newly found Neptune satellite S/2003 N1 showing its motion relative to background stars and galaxies. Click on the image to learn more.

The new Neptune satellite S/2003 N1 (now named Psamathe) was announced on September 3, 2003 by the International Astronomical Union. Read the circular announcement below. The new Neptune satellite is about 38 kilometers in diameter and has an orbital period of about 26 years. It is the furthest known satellite of any planet.

See a table of Neptune's known satellites .

Circular No. 8193
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)
URL  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)

     On Sept. 1, S. S. Sheppard, University of Hawaii, reported to
the Minor Planet Center the discovery by D. C. Jewitt, J. Kleyna,
and himself of a possible new satellite (mag R = 26) of Neptune
with the 8.2-m Subaru reflector at Mauna Kea on Aug. 29.3 and 30.3
UT.  He also reported observations from the same nights of S/2002 N
1 (IAUC 8047, MPEC 2003-A75).  Later that day, in response to a
request by B. G. Marsden (Minor Planet Center), M. Holman, Harvard-
Smithsonian Center for Astrophysics, reported observations by J.
Kavelaars and himself with the 4-m Blanco reflector at Cerro Tololo
on Aug. 21.1 UT of S/2002 N 1, as well as observations on Aug. 19.0
of another Neptunian-satellite candidate that Holman felt might
conceivably be identical with a satellite candidate observed in the
same manner on 2001 Aug. 11.1.  Computations by Marsden showed the
new Sheppard and Holman objects to be same and that identity with
the 2001 object was a distinct possibility.  Holman was then able
to locate this object, now designated S/2003 N 1, on two nights in
each of July 2003 and Aug. 2002 (with T. Grav and W. Fraser as
participating observers).  The complete set of observations and a
linked orbit by Marsden (a = 0.33 AU, e = 0.27, i = 124 deg, H =
10.8) are given on MPEC 2003-R19.  The 2003 observations (including
also some from June 3 and July 29 with the 6.5-m Clay reflector at
Las Campanas) of S/2002 N 1 are given on MPEC 2003-R18, together
with Marsden's improved orbit (a = 0.11 AU, e = 0.26, i = 112 deg,
H = 9.8).

                      (C) Copyright 2003 CBAT
2003 September 3               (8193)            Daniel W. E. Green


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