Celestia Forums

S/2003 N 1, a new satellite for Neptune:

distance from Neptune: 0.329 AUs (about 49.5 million km)
orbital period: 26.34 years !
eccentricity: 0.268
inclination: 124.23°
diameter: 38 km

So this moon's greatest distance from Neptune is larger than minimum distance of Earth and Mars!

sources: MPEC 2003-R19, Neptune satellite data

Also S/1986 U 10, Uranian moon discovered from old Voyager 2 photographs has been recovered, so it is real.

S/2003 N 1, a new satellite for Neptune

Yay!

So this moon's greatest distance from Neptune is larger than minimum distance of Earth and Mars!

Also S/1986 U 10, Uranian moon discovered from old Voyager 2 photographs has been recovered, so it is real.

Brilliant! I had a strange feeling there was something about that moon, something interesting that I shouldn't delete it from my tiny moons file...

JackHiggins wrote:I had a strange feeling there was something about that moon, something interesting that I shouldn't delete it from my tiny moons file ...

Trouble is, the only thing we knew about it for sure was that the published orbital elements were wrong ... otherwise it would have been picked up again easily.

No sign of planetocentric elements from Horizons on either of these, yet.

Grant

Trouble is, the only thing we knew about it for sure was that the published orbital elements were wrong ... otherwise it would have been picked up again easily.

But if the elements were wrong, how would they know that it's the same moon as imaged by Voyager 2...? It could be something else so couldn't it?

JackHiggins wrote:But if the elements were wrong, how would they know that it's the same moon as imaged by Voyager 2...? It could be something else so couldn't it?

The deal is that you publish a set of elements and someone then has to recover the satellite, demonstrating that its position is correctly recorded, before the IAU will think about giving it a name. My recollection is that the IAU actually withdrew recognition of S/1986U10 because nothing was showing up in the region stipulated by the elements. (The long delay between imaging and discovery couldn't have helped, since even small errors would add up over the years.) So the published orbit must have been wrong. Of the original seven images of S/1986U10, you've got to deduce that some were photographic flaws or some other object.
But then if you discover a new satellite, you work out the provisional elements and go back and look for it in old images so that you can tighten the definition further. I'm guessing that the discoverers found that their new body accounted for some of the objects seen on the old Voyager 2 images.
(Similar thing happened with Janus and Epimetheus, which between them probably accounted for various sightings of a satellite which was called "Janus" by Earth-based observers, but which never quite settled down into a predictable set of orbital elements until the true situation was revealed by spacecraft visits.)

But your links don't provide any information about this relocation, Ynjevi, and I'm not finding any new information with a Google search. Where did you find out about it?

Grant

But your links don't provide any information about this relocation, Ynjevi, and I'm not finding any new information with a Google search. Where did you find out about it?

See IAUC's Astronomical Headlines which has line

S/1986 U 10 = satellite of Uranus recently recovered. IAUC 8194 (2003 Sept. 3).

IAUC 8194 isn't yet available to non-subscribers. Also, satellite count for Uranus in Sheppard's Jupiter irregular satellites page has risen back to 22. That's all I know.

Ynjevi wrote:See IAUC's Astronomical Headlines

Thank you!

Grant

Update:

Two more satellites, S/2003 U 1 and S/2003 U 2 have been spotted orbiting around Uranus. Unlike most new satellites, these are inner satellites and were found by Hubble Space Telescope. S/2003 U 1 is 16 km wide and S/2003 U 2 is 12 km, being smallest known Uranian satellite. Offical IAU announcement will come later today.

See Space.com article

HST press release is now available.

Update:

New satellites for Uranus and Neptune:

S/2001 U 2

a = 21,000,000 km
i = 167.3 deg
e = 0.426
p = 2823.4 days
diam = 12 km

S/2002 N 4

a = 47,279,670 km
i = 139.3 deg
e = 0.605
Peri = 89.7 deg
Node = 52.2 deg
M = 253.9 deg
p = 9007.1 days
diam = 60 km

... so S/2003 N 1's record didn't hold for long

Also, Neptune's new satellites found in 2002 have all been recovered and their data should be updated.
From Jupiter Irregular Satellite and Moon Page

Ynjevi wrote:Also, Neptune's new satellites found in 2002 have all been recovered and their data should be updated.

They already have been.
See the following thread for the updated data, or download a new numberedmoons.ssc from the CVS tree: http://celestiaproject.net/forum/viewtopic.php?t=3353

Grant

granthutchison wrote:

Ynjevi wrote:Also, Neptune's new satellites found in 2002 have all been recovered and their data should be updated.

They already have been.
See the following thread for the updated data, or download a new numberedmoons.ssc from the CVS tree: http://celestiaproject.net/forum/viewtopic.php?t=3353

Grant

Thanks, I'll do that
Just pointing out that because a new MPEC for S/2002 N 3 was published yesterday.

And here's the definition for 2002N4, converted to Celestia coordinates from the brand-new JPL Horizons ephemeris for that body - it's slightly at variance with Sheppard's provisional figures.
I've updated numberedmoons.ssc on the CVS tree too, of course, though the change can take a little time to come through.

Grant

And the Horizons ephemerides for 2002N2 and 2002N3 have been re-revised today. New Celestia elements as follows:

Grant

S/2001 U 3:

a = 0.0285437 au
e = 0.1425279
i = 147.61337°
P = 266.57 days
Peri. = 123.18537°
Node = 103.05787°
H = 12.8 (-> a bit smaller than S/2001 U 2)

MPEC 2003-T29

S/2003 U 3:

a = 0.0979247 AU
e = 0.7826995
i = 50.65125°
P = 1693.88 days (4.64 years)
Peri. = 77.97150°
Node = 18.01185°
H = 12.7 mag

MPEC 2003-T58