Re: JPL HORIZON site - "on the fly" predictions

Tony Beresford (
Fri, 25 Jun 1999 22:52:39 +0930

At 18:40 25/06/99 , Ed Cannon wrote:
>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.
I think he/she means observing campaign at least sanctioned by ESA Ed
>>    ... 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.
As I mentioned to Ed before its trivial to get mean anomaly from
true anomaly  via the Eccentic anomaly and keplers equation
What you dont have is the epoch time of the elements!
Tony Beresford