Quicksat problem?

Edward S Light (light@argos.argoscomp.com)
Mon, 21 Oct 1996 07:34:44 -0400

On Sunday 20 October 1996, Ala' Shahin wrote:
> 
> I have downloaded Quicksat but I guess I am having
> some troubles making it work right.
> 
> In most cases I get Tim value of 29.9 ....
> I don't know what is wrong ... it is supposed that
> the element file is fresh.
> Can anyone tell me what is wrong?
> 
> 
The problem is that the element file is NOT fresh; Quicksat includes in
its results a column called "Dys" which is, essentially, how many days old
that satellite's elements are. For example, in your sample:
> 
> ***  1996 Oct  20  Sun evening  *** Times are PM CDT ***  1829  547
> 
>  H  M  S  Tim Al Azi C Dir  Mag Dys F  Hgt Shd  Rng  EW Phs  R A   Dec
> 
> 20322 CoBE           4.9 8.5      16 2.5   4.5
>  7  8  5 29.9 24  47   255  6.32287 0  526  34 1047  .8  38  238  47.9

this line has a Dys value of 287, meaning that the elemtents are over 9
months old. Quicksat's estimate of time uncertainty ("Tim") is, as you
noted, "29.9" minutes, a not-unreasonable value for such "old" elements;
in fact, the "real" value may be much larger. I believe Mike McCants prints
out "29.9" for any prediction for which that quantity is equal or greater
than that value.

Running your control file information against tle.885, a recent elements
file, produces, for example:

  32.000  36.000 2450.      AMMAN, JORDAN       2000  8.0 15 F F T T T

***  1996 Oct  20  Sun evening  *** Times are PM CDT ***  1829  547

 H  M  S  Tim Al Azi C Dir  Mag Dys F  Hgt Shd  Rng  EW Phs  R A   Dec

20322 CoBE           4.9 8.5      18 2.5   4.5
 6 34  3   .0 52 167     4  5.4   4 0  547 464  671 1.5  76 2041  -5.5
 6 35 31   .0 89 261 C  95  4.9   4 0  546 470  547 1.8  79 20 7  31.7
 6 37  0   .0 52 346   175  5.5   4 0  546 476  671 1.3  86 1837  67.4

In this case, the elements for this object are just four days old.

Clear and dark skies!
   Ed Light

Lakewood, NJ, USA
N 40.1072, W 074.2317, Hgt +21m