Re: Planet X: ALTERNATIVE Garbage <= THOLEN 3

On Article  <[email protected]> David Tholen wrote:
> In Article <[email protected]> (Intruder) writes:
>> it is peculiar that the orbital elements of 2001KX76
>> are available on Harvard MPC but the article speaks
>> of an `Uncertain Orbit' how touchy
>
> What is so peculiar about it?  The orbital elements can
> be both available and uncertain.  You can still have a
> "best fit" in the least-squares sense and large error bars
> on the fitted parameters.
>
> For example, the following two orbits both fit the
> observations of 2001 KX76 equally well (to 0.5 arcsec RMS):
>
> a = 239.60109
> e =   0.87381
> i =  14.039
> N =  73.407
> w = 235.911
> T = 2461862.283
>
> a =  43.12019
> e =   0.59994
> i =  24.412
> N =  69.841
> w = 304.648
> T = 2468996.172

As I recall, when Hale-Bopp was all the rage in 1995, that it took only
THREE positions to determine the orbit!  Why have things changed?  Below
is a press release on Hale-Bopp showing that IN A WEEK they were able to
come up with their projected orbit.  Within two days, the orbit was
“highly uncertain” but when July 24-Aug 1 was considered, they HAD it,
so said they.  Have we not watched this new KBO that long, more than a
week?  We’ve had since 1992 to watch other KBOs, have 300 of them to
date, but we still don’t know their orbit patterns?

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Washington University
Gary W. Kronk
1995 Aug. 3
C/1995 O1 (Hale-Bopp)
(Orbit on IAUC 6198)

Green issued IAUC 6191 on July 26, which gave the first orbit
computation (listed as highly uncertain). Based on 57 positions obtained
on July 24-26, it indicated the comet would pass perihelion in early
1997! Brian Marsden (Central Bureau for Astronomical Telegrams) issued IAUC
6194 on August 1. It gave a parabolic orbit based on 208 positions
obtained during the period of July 24 to August 1. This new orbit, which
is still considered "somewhat uncertain", had a perihelion date of April
1, 1997, and a perihelion distance of 0.9 AU.  McNaught's prediscovery
image was announced on IAUC 6198 and enabled Marsden to compute a very
precise orbit. This new orbit indicated the general correctness of the
orbit on IAUC 6194, except that the comet is moving in a long-period
ellipse. It currently has an orbital period of about 4000 years, but the
original orbit may have had a period of about 3200 years. Marsden
comments that comet Hale-Bopp "is not on its first pass from the Oort
Cloud."