JPL HORIZON site - "on the fly" predictions

Ed Cannon (
Fri, 25 Jun 1999 04:10:10 -0500

I heard from someone at JPL:

>    We'll consider adding Giotto flyby as a predefined object in 
> the next day or two....  Is there an observing campaign for the 
> Giotto flyby?

I replied that I think it's certainly a possibility.

>    ... you can input the elements yourself and develop an 
> ephemeris "on the fly".  
>    At the main "telnet" prompt, type a semi-coloni (';') and 
> return to drop into user-defined object input.  Type a question 
> mark ('?') for an explanation of how to input the elements.

This person also reiterated the need for or at least usefulness of
a couple of other element details:

> (I should add that we would need the Epoch of the heliocentric 
> osculating elements and, preferably, mean anomaly instead of true.  
> Alternatively, time of perihelion and perihelion distance.)

Hopefully the extra details will become available.

By the way, I saw a photo of Giotto on Mark Wade's Encyclopedia
Astronomica site, and it's mostly a dark-colored cylinder!

Ed Cannon - - Austin, Texas, USA