Kalliope and Linus

[eburacum45]

I'm making an add-on for the double asteroid Kalliope, but I need a little help;
this will be a fictional add-on for John Dollan's Arcbuilder's universe, and will incorporate some ancient ruined structures...



but I would like to get the orbit fairly accurate;

here is what I have so far

Code: Select all

"Kalliope" "Sol"
{
   Class "asteroid"
   Mesh "kalliope.3ds"
   
   Radius 115

   EllipticalOrbit
   {
   Period            4.9611
   SemiMajorAxis     2.908783
   Eccentricity      0.10282
   Inclination       13.7101
   AscendingNode   66.2409
   ArgOfPericenter 356.21378
        MeanAnomaly       283.6
   Epoch       ?
   }

   RotationPeriod   0.1728
   Albedo            0.2
}

"Linus" "Sol/Kalliope"
{
   Class "asteroid"
   Mesh "linus.3ds"
   
   Radius 19

   EllipticalOrbit
   {
   Period            3.59
   SemiMajorAxis     1065
   Inclination       93.4
   }
   RotationPeriod   0.1 # Guess
   Albedo            0.2
}



taken from here
http://www.johnstonsarchive.net/astro/a ... 00022.html

(with some rounding of figures - have I rounded too much?)

I am puzzled about how to obtain the epoch, though:
any other problems?
Has anyone made these two 'roids before?

[selden]

with some rounding of figures - have I rounded too much?

Why round at all? Celestia can accept the equivalent of double precision values, whether or not it actually uses that precision to do its calculations.

I am puzzled about how to obtain the epoch, though:

The epoch is on the Web page that you cite:

Code: Select all

Epoch:    18 AUG 2005

You can either convert it to Julian or specify the numeric Gregorian date as a quoted string:
either

Code: Select all

Epoch 2453616.5

or

Code: Select all

Epoch "2005 8 18"

(I usually use the date convertor at http://aa.usno.navy.mil/data/docs/JulianDate.html)

Has anyone made these two 'roids before?

I don't think so.

[eburacum45]

eburacum45 wrote:
with some rounding of figures - have I rounded too much?
Why round at all? Celestia can accept the equivalent of double precision values, whether or not it actually uses that precision to do its calculations.

That is interesting. I rounded the figures because they seemed too precise- surely an asteroid's orbit is too easily perturbed to merit ten places of decimals.
But I'll put them back to the published figures; that is easier after all.

The epoch is on the Web page that you cite: Code:
Epoch: 18 AUG 2005

You can either convert it to Julian or specify the numeric Gregorian date as a quoted string:
either
Code:
Epoch 2453616.5
or
Code:
Epoch "2005 8 18"

aha! that second option is the one I was looking for; it is a lot easier than adding days up.

Thank you, selden.

(new image)
http://img66.imageshack.us/img66/6213/linus9ft.jpg

[selden]

I rounded the figures because they seemed too precise- surely an asteroid's orbit is too easily perturbed to merit ten places of decimals.

They are too precise to be entirely valid, but that's just because the authors provide the full output of the program that fits an elliptical orbit to the observed positions. They really should provide the calculated errors on each of the values, but that's not usually done.

[The Singing Badger]

Kalliope is in Jack Higgins' binary asteroid SSC file. Might be useful as a comparison.

http://www.celestiamotherlode.net/catal ... ddon_id=12

[eburacum45]

So it is; thank you.
The orbital parameters are very similar but not identical; and Linus is only roughly described in Jack's version.
So to avoid confusion I'll call my version 22 Kalliope; it will eventually be available as two versions, one with ruins (for John Dollan's Arcbuilders Universe )and one without.