Home Planet satellite inaccuracies

I have been using Home Planet
(http://fourmilab.ch/homeplanet/homeplanet.html) for a few days, and
have noticed some inaccuracies with the satellite tracking. For
example, the position of ISS (ZARYA).

Orbital tracking (http://spaceflight.nasa.gov/realdata...ing/index.html)
returns this data:
37.6 S
38.9 E
Alt. 379.24 km

Home Planet's default SATELITE.SAT returns this data (rounded):
9.4 N
51.4 E
Alt. 288.89 km

And the current NORAD two-line element set from Celestrak
(http://celestrak.com/NORAD/elements/stations.txt) returns this data
(rounded):
25.7 S
31.4 E
Alt. 378.60 km

Also note the conflicting positions of TERRA (http://terra.nasa.gov/)

From SATELITE.SAT:
11.27 S
80.71 E
Alt. 655.57 km

From Celestrak (http://celestrak.com/NORAD/elements/resource.txt):
64.33 S
33.94 E
Alt. 702.95 km

Now, my questions: Why don't both the SATELITE.SAT and Celestrak data
approximate the actual position of the ISS? How can I fix it so they
do? Which data sets are more trustworthy/accurate: the default
SATELITE.SAT or the sets from Celestrak? Is there a more accurate
source for two-line element sets?

Thanks in advance,
Zachary Antolak

(Zachary Antolak) wrote in message . com...
I have been using Home Planet
(http://fourmilab.ch/homeplanet/homeplanet.html) for a few days, and
have noticed some inaccuracies with the satellite tracking. For
example, the position of ISS (ZARYA).



Hi:

Unless you've updated Home Planet with the latest elements, there's no
way satellite positions will be correct.

Peace,
Rod