Re: Site information why elevation..

Edward S Light (
Wed, 9 Jun 1999 12:07:39 -0400 (EDT)

ykChia recently asked ...
>     I am curious why do we need to specify elevation in addition  to
> longitude and latitude. Does this affect the precise apparent
> positioning fixing of satellite? What is the error involved comparing say
> Sea-level vs someone high up in Colorado..

I did a quick experiment using quicksat with my latitude/longitude but
for two different elevations: 0 and 10,560 feet (= 2 miles = 3.22 km).
For one night's worth of predictions (of "LEO" objects), the largest
difference in culmination point (basically, the highest part of a pass)
seemed to be about 0.1 degrees in declination and/or 1 minute of Right
Ascension. So unless you are into precise positional measurements,
the elevation probably isn't worth worrying about.

Clear and dark skies!
   Ed Light

Lakewood, NJ, USA
N 40.1072, W 074.2317, Hgt +21 m (69 ft)