Alessandro Feb 2, 2013
--- In find_orb@yahoogroups.com, Bill Gray wrote:
>
> Hi Alessandro,
>
> > I just realized that the dT difference depends heavily on weather the asteroid perturbation
> > effect is taken into account or not...
>
> AHA! You are absolutely correct about this. My apologies for misleading you about the
> "timing error".
>
> (70401) Davidbishop passed within about 400000 km of Pallas on 1982 Feb 27. It's really
> rare to see cases where asteroid perturbations matter very much, but they certainly do here.
> If you toss out the five worst observations and include asteroid perturbations, you get
> an RMS error of 0.663". Shut off the perturbations and do a full step, and that bounces
> back up to 1.124, with the 1950 observations having 14.5" residuals in RA.
>
> You could actually use this to get a decent estimate for Pallas' mass. I've occasionally
> thought about revising Find_Orb to do that sort of thing. It would basically just have to
> solve for seven parameters: the usual six orbital elements it normally solves for, plus
> the asteroid mass. Not a big deal, and possibly useful to people doing asteroid mass
> determinations (I don't know what they currently use.)
>
> -- Bill
>