[time-nuts] HP 58503A

Jim Lux jimlux at earthlink.net
Fri Aug 3 13:31:06 UTC 2012

On 8/2/12 6:24 PM, Doug Reed wrote:
> I ran into a wiki description of GPS using WGS84 a couple days ago. It
> included a mention of ESEC and it was something like: Earth Static,
> Earth Centric. I think I was following a link about the Z3801A.
> It referred to the fact that lat-lon is referenced to a static grid on
> the Earth and doesn't change as the Earth rotates on its axis or around
> the sun. Earth static and Earth centric.

Earth Centered Inertial - ECI   centered on the earth, doesn't rotate 
with earth - very popular with earth orbiting satellites, because their 
"center of rotation" is at the center of the earth but their orbital 
plane is fixed in celestial terms.  like RA/Decl

Earth Centered Earth Fixed - ECEF (or ECF)  centered on earth, rotates 
with earth.  More like conventional lat/lon.

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