[Chaos-l] Comet 103P/Hartley 2

[Tony Rice]

Sounds like your software's ephemeris data is a bit out of date.
Earth and Moon themselves and even asteroid belt objects can alter the
path enough to introduce significant error into old orbital data.   My
software with the latest data from JPL's Horizon system
(http://ssd.jpl.nasa.gov) puts 103P/Hartley about a degree and a half
on Oct 1 which lines up with Sky and Telescope's chart.

If your software can update it's orbital data, see if it can take
output from Horizon.  If not, let me know what parameters it uses for
solar system objects (epoch, inclination, mean anomaly, etc.) and we
can get it updated.

-Tony

On Wed, Sep 29, 2010 at 9:15 PM, Robert Nielsen <robertnielsen at nc.rr.com> wrote:
> Tony (or someone else),
>
> I'm confused.   According to the chart and text in the Sky and Telescope
> article, Comet 103P/Hartley 2 should be right next to Alpha Cassiopeiae on
> October 1st.  But both of my planetarium programs show it way down in Auriga
> on that night.
>
> Which is it?  Am I looking at erroneous data ... or the wrong comet?
>
> Robert
>
> On 9/29/2010 11:21 AM, Tony Rice wrote:
>
> Comet 103P/Hartley 2 is approaching and will be in a easy to locate
> spot (near Cassiopeia) over the next couple of weeks.  But at
> magnitude 5-6 will be a bit of a challenge to observe in light
> polluted skies.
>
> http://www.skyandtelescope.com/observing/home/102632669.html
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