Satellite Suitability For Masts, Spires, Etc

[ArtMan]

Generally, a station is suitable for satellite observations if there is a clear and unobstructed view of the sky from approximately 15 degrees above the horizon at the location of the station. Small objects such as a light pole or small tree are excepted.

 

Is this station suitable for satellite observations?

_Yes _No _Don't know

 

That's the question you get when filing an NGS recovery report.

 

What's the correct answer for objects such as radio/TV antennae, tall standpipes, church spires, etc. - in other words, structures normally observed from afar, rather than occupied at the geodetically-significant point?

 

Technically, I suppose, one could hoist survey-grade GPS gear up to the top of an 900-foot broadcast mast or to the cross atop a church steeple, and indeed you would get a clear view of the GPS constellation. But I also suppose that is not done often, if ever. (Usual exception for the NGS crew who heroically climbed the Washington Monument to take observations for WASHINGTON MONUMENT 1913 - HV4442.)

 

But seriously, what is the correct response here? I've been entering "Don't know," but I welcome correction.

 

Thank you,

-ArtMan-

[evenfall]

Artman,

 

The Landmark stations were optically intersected, they were never occupied and are not considered occupiable. The are just low order optical triangulation. You could consider them a helper station. The used them as swing points for establishing 3rd order triangulation in low areas where towers were not feasible or timely. 4 observations will get you third order Horizontal and a landmark could be seen from many different locations surrounding it. They served that purpose. They are not suitable for GPS observations because there is no way to perform an instrument set up on them, So Landmarks that are intersected points are a NO. They are not suitable for GPS Observations. Further for the safety of all concerned, The ground is a safe place to be. Climbing on these landmarks is probably not a real safe thing to attempt.

 

The NGS did the Washington Monument because they could. The scaffolding was already in place for another purpose, and since the last time they had scaffolding on it an instrument was set up, they wanted to compare the numbers... Mostly because they were afforded the opportunity, and for the adventure of it.

 

Rob