Suitability For Satellite Observations

[+Gambrinus & Crew]

Hi,

 

Rookie needing guidance here....

 

When doing a mark recovery with the NGS for a found mark, you are prompted for suitability for satellite observations. The message that appears on that screen is as follows:

 

"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."

 

Most often, it's pretty clear that a mark either is or isn't suitable, but in some cases, I've answered that I don't know. Does the description above mean that 360 degrees around the mark needs to be unobstructed from 15 degrees above the horizon and up? Or does it expect some portion of that circle to be unobstructed.

 

I found a bench mark today that was along a 4-lane divided highway. On the side the disk was on, there were trees 100 feet away or so and so that direction would not be considered unobstructed. Across the street, however, there is some kind of construction going on and it's very unobstructed that way.

 

I answered that I didn't know to the prompt in question. What would be the correct answer?

 

Thanks much!

[+Kewaneh & Shark]

This topic was discussed a few months ago in the thread titled Suitable For Satellite Observation?

 

You may find some additional info to help answer your question there.

 

- Kewaneh

[Z15]

Does the description above mean that 360 degrees around the mark needs to be unobstructed from 15 degrees above the horizon and up.

 

YES, thats what it mean.

 

Single items like poles and samler trees may not have any effect but that is a judgement call. If they are close it balcmks out more sky than is they are several hundred feet away. 100 ft is borderline, trees always grow so what seem ok today, maybe no good in 5 yrs. When in doubt, put I don't know.

 

A simple means to detemine the 15° is to hold your fist (thumb up) level with the horizon, every fist is about 5°.

 

The reason for the 15° is that you want to see all avaialbel SV's for the best geometry.

Edited July 22, 2006 by Z15

[+Gambrinus & Crew]

Thanks, for the link and the info. I had searched in this forum because the question was specific to the NGS, but didn't in the other forum. Live and learn...

 

Thanks again. Interesting reading in the linked thread.