Satellite question

[Johnny5]

There is a Navy destroyer, at sea, 10 nautical miles offshore from the florida keys, parallel to the equator.

 

They are trying to locate the intelsat 803 satellite.

 

Does anyone know how to tell them what their azimuth and elevation needs to be in order to locate it.

 

Does anyone know how to construct a formula for az and el?

 

Thank you

[Johnny5]

In order to answer this question, one has to know the orbital slot of the satellite.

 

The satellite is in the equatorial plane of earth, and it is at an altitude such that the satellite is in geostationary orbit. This means it hovers over the same position above the land, 24 hours a day, 7 days a week.

 

That altitude can be deduced, using conservation of energy, but it's been awhile since I actually carried out the calculation.

 

As for the orbital slot of the Intelsat 803, that can be found from Intelsat's website. Actually, I think they changed it to New skies.

 

So change the satellite to Intelsat 901, here is the link

 

Orbital location of IS-901

 

The orbital location is given as 342 degrees east, which is the same as 18 degrees west.

 

To understand where this is, in relation to the surface of the earth, simply look at a worldmap, and find the point (0,0). That point happens to be six degrees of latitude south of Accra Ghana, which is in Africa. Then move to the west 18 degrees of longitude. Then, imagine a straight line through the center of the earth, through the point 0 N latitude, -18 E longitude, extending all the way into space, and terminating at the position where a satellite would be in geostationary orbit.

 

Then, figure out where the ship would be. The given information was that it was 10 nautical miles east of the Florida Keys.

 

1 nautical mile is 1852 meters.

 

So figure out the latitude, and longitude of the ship.

 

Then treat the earth as spherical, to a first approximation. Later this can be corrected for, by treating the earth as an ellipsoid.

 

The mean radius of the earth, is something like 6300 kilometers.

 

Then, from there, figure out what the azimuth, and elevation are, for the ships antenna to be aimed at the satellite.

 

If no one answers this in the next few days, I will work on it.

 

My first step would have to be, to calculate the location of geostationary orbit, in say kilometers above the surface of the earth.