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Old 13-01-2020, 08:01 PM
Dazzled by the Cosmos.

Dennis is offline
Join Date: May 2005
Location: Brisbane
Posts: 10,975
Originally Posted by gary View Post
Hi Dennis,

The problem originates at the Minor Planet Center (MPC).

2I/Borisov has a very, very high orbital eccentricity (in the order of ‎3.3575)
and the orbital elements are just the solution for a two-bodied problem.

The orbit is sufficiently perturbed that unless you are using very recent
orbital elements (check the epoch), the computed position will be
degrees out.

Something is up at the MPC. The elements they have been publishing
for the software packages for some comets have epochs that are
weeks and months out of date compared to the recent epochs used
for the orbital elements they also publish separately as raw data.

The asteroid elements for the software packages are even worse
where they were last computed for epochs in 2018.

Many of these orbits have been perturbed since then.

They had some computer system failures some time back and things have
been out of kilter since then.

The workaround is to use the data either they or JPL supply when
you examine an individual object and synthesise the elements from that.

How you then load your own elements into the package of choice I will
leave as an exercise for you but it may not be possible for all packages.

Alternatively, just use the MPC web page that allows you to compute the
RA/Dec position at multiple points in time, say every 5 minutes in the evening.
Those positions are accurate.
Thanks Gary, I appreciate your insight into the problem.

In the end, it was 2 phased issues with The Sky X Pro.
  • First of all, TSX was not (originally) designed to handle objects with the large/unusual eccentricity of 2I/Borisov, but the Bisque Website provided what they reasonably believed to be a suitable, interim solution whilst also notifying their user community of a soon-to-be released Daily Build that would fix that issue.
  • Then, the interim solution proposed, which was to point the Comet Input dialogue to an external 3rd party set of elements, did plot the comet but unfortunately, there may have been some issue with the accuracy of those elements as the plotted position of the comet was a few degrees off.
The Bisque website also provided another solution, which was a Copy/Paste of the elements from the JPL Horizons website which did plot the real position, but by then, the clouds rolled in and have hung around so I havenít had the opportunity to try again.

Cíest La Vie.


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