Re: [find_orb] Re: Positional uncertainty PA value?

aje160744 Nov 12, 2014

Andy,

If you were to imagine that the 6 observations in your post were the "discovery" observations of a new object then the main objective would be to get a good enough position for follow up observations the next night. In fact FO gives such a good initial orbit that its "predicted" position 24 hours later is within one arcsecond of the "correct" position we can get using all the available obs.

You can force FO to give an uncertainty by setting the constraint e=0.35 (approx its original suggestion) and repeating Full Step until eccentricity converges to near 0.35. This gives (with my settings) an uncertainty of 14" 24hrs later.

Of course, this object is a Mars Xer so its movement is nice and sedate and a relatively easy solve for FO. Interesting challenge for students would be the initial observations from a close passer NEO.

Tony