Re: Hale-Bopp THEN and NOW (1-6)

Article: <[email protected]>
From: [email protected](Nancy )
Subject: Re: Hale-Bopp THEN and NOW (1-6)
Date: 15 Feb 1997 21:08:15 GMT

In article <[email protected]> David Brooks writes:
>>> ISSUE 6: Why would a comet PERTURB AWAY from
>>> Jupiter? Isn't this backwards?
>>
>> 1. What information leads you to believe that a perturbation
>> away from Jupiter has occurred? More of your 'jerking'
>> all around the sky?
>> [email protected] (Greg Neill) writes:
>
> Nancy's claim that the comet perturbed away from Jupiter
> was based on one of Marsden's (or was it Yeoman's)
> ephemeris refinements. It caused a jag in her plots at
> what she described as the "closest approach to Jupiter".
> Unfortunately, the time in question wasn't even close
> to perjove. It happened when the angular separation
> between the comet and Jupiter was narrowest, long
> after the actual closest approach. I believe there had been
> times when the separation was narrower (less than 7
> degrees).
> [email protected] (David Brooks,139,7233)

For those unfamiliar with what we're talking about here, the pertinent information that started this discussion is posted below, at the bottom of this post.

David, can we get specific? Exactly what date would Jupiter have had the strongest influence on the mythical Hale-Bopp? The control point here is the May 28, 96 date. JPL posted the RA and Dec for May 28, '96. JPL also references this date every time they post new Orbital Elements, as one can put these elements into a program such as SkyMap and find the RA and Dec where the comet would be at any particular date. I did that for the Orbital Elements JPL posted on June 27, '96 to get the RA and Dec for May 28, '96 as it had been changed. The May 28, '96 RA and Dec show Hale-Bopp in a closer position to Jupiter ON MAY 28, '96 than the June 27, '96 Orbital Elements do for that same date. The June 27, '96 Orbital Elements show Hale-Bopp ON MAY 28, '96 as being further AWAY from Jupiter.

Closeness to Jupiter on May 28 using JPL May 28 Orbital Elements

Closeness to Jupiter on May 28 using JPL June 27 Orbital Elements

How, weren't these Orbital Elements based on observations? So, they observed that Hale-Bopp jerked away from Jupiter, perturbed away. This is my point. Be specific with your dates and distances, David, so we can have a proper discussion here.

............

From the Troubled Times web site at

http://www.zetatalk.com/halebopp/hb000028.htm

On May 28, '96 JPL posted new orbital elements for HB, which when placed into my Skymap program come up the a RA and Dec for that date of

Presumably HB was observed to be there, else why the need to correct NASA's Feb 22, '96 orbital elements. Then on June 27, '96 JPL came back and posted new orbital elements. Presumably they had observed HB changing position, and thus the need for new elements. When I place the June 27, '96 elements into my Skymap and compare the RA and Dec to where the observed position of HB on May 28, '96 would have placed it, I find the mythical HB moving further away from Jupiter, at a time when it is passing Jupiter.

Do comets lurch away from their perturbing influences, the giant Jupiter?