Re: Coping with old elements sets and orbital decay, was RE: TiPS tether seen

Ted Molczan (
Sun, 29 Sep 1996 21:45:26 -0400

The following was supposed to have been
sent to Seesat-L on 23 September, but somehow, 
I managed to mail it to myself!

In my post regarding my method to estimate the
prediction uncertainty in satellite ephemerides,
I made the following erroneous statement:

>The constant 876 is simply the number of seconds in day, divided by
>100. It enables UNC to be expressed in seconds of time, and converts 
>%UNC into a fraction.

Russell Eberst and Mike McCants have kindly pointed out
that 876 is not the number of seconds in a day divided
by one hundred. The correct answer of course is 864, so
my formula should be:

UNC = 864 * %UNC * ndot/2 * dt^2
         n0 + 2 * ndot/2 * dt

The 2 percent error in the original does not invalidate
the basic findings in my article, and it does prove what 
I said a little later in my message:

>I will leave the derivation up to the reader. It involves only high
>school math, and I suspect many of us who are long out of school
>can use the practice. 

Yes indeed!
Ted Molczan