Celestia Forums

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


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?

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.

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

The epoch is on the Web page that you cite:
You can either convert it to Julian or specify the numeric Gregorian date as a quoted string:
either
or

(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.

selden wrote: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.

selden wrote: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

eburacum45 wrote: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.

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

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

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.