On Wed, 28 Feb. 2018, 1:12 am Bill Gray pluto@... [find_orb], <find_orb@yahoogroups.com> wrote:

 

Hi Alan,

Sure, go ahead and post positions. I'm glad to hear you're
measuring STEREO positions; it seems to me to be an under-used
resource.

Getting orbits from STEREO and SOHO data tends to be a bit
painful. You don't get parallax and the positions aren't nearly
as exact as those from ground-based astrometry. It used to be
that MPC would produce orbits from SOHO and STEREO data, but
I think a lot of the knowledge of how to do that was in Brian
Marsden's head. I computed orbits for a few hundred comets
some years back, and we now have a tremendous backlog of comets
for which orbits need to be computed... it's been on my 'to do'
list for a few years now.

However, if you just have one or a few objects, things ought
to be somewhat more straightforward.

Also be warned: if you can get the object from _both_ STEREOs,
or from a STEREO and SOHO, you'll get an _immensely_ better orbit.
(Which is why I'm glad to hear of STEREO positions being measured.
Comets measured just using SOHO -- the usual case -- tend to have
extremely approximate orbits, unless they were bright enough to
be measured over a couple of days.)

-- Bill

On 2018-02-27 07:35, c2009a1@... [find_orb] wrote:
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> Gidday All,
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> I joined this forum, as I now seem to be able to measure data from STEREO HI1a images that can be used with Find_Orb. So, sorry if you have answered these questions all before.....
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> So, just to introduce the problem, I can see many known asteroids in STEREO HI1a images. Most I can name from general alignments in Starry Night software with mpc data files. I want to rework the orbit calculation for some of these from measures from HI1A positions. To prove I have a good processing model to get real orbit elements.
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> Well, I have an unknown object ( unknown to me) moving across the fov for a month,  have tried with  help from Stereohunter forum members to work an orbit. Karl B ( mr sungrazer) suggested contacting Bill for help.
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> I have the input data files available that have GEI position info for the Stereo satellite. Not that I know what a good solution looks like other than low residual numbers. Need to lock a good solution so that the unknown can be named.
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> Can I share the positions file here??
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>
> Kind regards, Alan Watson
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