Question

I have been given output in (what I believe to be) ECI format (from OrbitTools):

TSINCE X Y Z

0.00 4733.08693007 5370.64476064 0.09227655
360.00 -3928.94737512 -4784.93071195 -3602.13095174
720.00 2078.23905091 2928.47218732 6181.06427083
1080.00 343.60889986 -292.76288815 -7150.74620799
1440.00 -2682.96778230 -2415.73481378 6170.18900818

and need to convert the x,y pairs to latitude/longitude (to plot on a map where the object is above).

I can't reason through the conversion.

Is there a document that a laymen could get through or formula that would take a given time/point and yield a terrestrial latitude and longitude?

Answer 1

I just did a bit of research on the internet and came across this (http://celestrak.com/columns/v02n01/). It gives a good explanation of how to convert between the two co-ordinate systems.

It seems getting the latitude from ECI is straight forward.

Z=Rsin? where R is the height of the above the centre of the Earth and ? is the latitude. X and Y are a bit difficult to convert and you will need to work through the document I linked.

Hope this helps (and hope this is related to what you were looking for)