Help me find an "accurate" Witness Post

[+Woodstramp]

My brother is interested in Geocaching. I just ordered him a unit just like mine...a Magellan Explorist 400. I've about got it ready (Detail Maps loaded) to send to him.

 

A few months ago I came here looking for help to check the accuracy of my GPS by finding benchmarks in my area. Some poster was kind enough to find one that was near me and it was what is called a witness post. Anyway, the coords the poster listed were dead on. I was able to drive right up to it. The poster mentioned that the ones I'd attempted (and failed) were not really accurate BM's. They hadn't been "adjusted" or something like that. I've found a few listed on Geocaching.com, but I don't know how to tell which are "easy" ones to find.

 

I'm looking for something simular (witness post) between Gillette, WY and Wright, WY on Hwy 59 for him check his unit when he gets it. A little practice before geocaching and to boost his confidence in the abilities of the GPS. He's never used one before.

 

Thanks.

[Bill93]

"Adjusted" horizontal location is what you want. That means the NGS compared it to other nearby stations in the network and adjusted its position to be as good as possible relative to the others.

 

In the list of markers, "Triangulation Station" is the best choice if it is at the surface. Tower, Spire, Stack, Tank, etc are accurate horizontally, but sometimes you can't get close enough to them to compare your unit. Some "Bench Mark Disk" are also horizontally adjusted but most aren't since their main purpose is elevation, not location. "Metal Rod" is often good in both position and elevation, but it seems that around Gillette they tend to be only for elevation.

 

PV0553 is one that is horizontally adjusted. Also PV0401 north of Gillette which was found in 2001 but not logged on geocaching. OU0397 south of Gillette was found in '86. You can click on "Nearby Benchmarks" to search for others. I wasn't immediately successful in picking one that someone else has found so we know it is easy to locate.

 

The opposite is "Scaled" which means someone used a measuring scale laid on a map to estimate the coordinates. These are routinely off 100 feet and sometimes much more, but if it is an elevation-only mark that doesn't affect its main use.

 

A Witness Post is just something to help find the real marker. Most are 1 to 3 feet away from the mark but sometimes further.

 

You can search the Geocaching data base of benchmarks here.

 

Another way to search is on the NGS web site under data sheets, radial search by coordinates or by county. Use "Any Horizontal Control" option.

[AZcachemeister]

bye

Edited May 20, 2008 by AZcachemeister

[2oldfarts (the rockhounders)]

Look at this one. It is located just south of Wright, WY. PID# OU0396 It is a WYOMING HIGHWAY DEPARTMENT "disc". The coordinates should take your brother right to the "Triangulation Station Disc".

 

Here is something similar to what he might see. I have posted one of our finds since none of those around his area have been recovered by any of the benchmark hunters from GC.

 

His will be "IN THE TOP OF A SQUARE CONCRETE POST". Where this Arizona Dept. of Transportation disc is in the top of a round concrete post, shown here...

 

 

Hey, Someone needs to recover all of these virgin marks! To see an area where the marks have not been reported on, seems to be an sin of some sort. Right?

 

I hope this helps some.

 

Shirley~

[+Woodstramp]

"Adjusted" horizontal location is what you want. That means the NGS compared it to other nearby stations in the network and adjusted its position to be as good as possible relative to the others.

 

In the list of markers, "Triangulation Station" is the best choice if it is at the surface. Tower, Spire, Stack, Tank, etc are accurate horizontally, but sometimes you can't get close enough to them to compare your unit. Some "Bench Mark Disk" are also horizontally adjusted but most aren't since their main purpose is elevation, not location. "Metal Rod" is often good in both position and elevation, but it seems that around Gillette they tend to be only for elevation.

 

PV0553 is one that is horizontally adjusted. Also PV0401 north of Gillette which was found in 2001 but not logged on geocaching. OU0397 south of Gillette was found in '86. You can click on "Nearby Benchmarks" to search for others. I wasn't immediately successful in picking one that someone else has found so we know it is easy to locate.

 

The opposite is "Scaled" which means someone used a measuring scale laid on a map to estimate the coordinates. These are routinely off 100 feet and sometimes much more, but if it is an elevation-only mark that doesn't affect its main use.

 

A Witness Post is just something to help find the real marker. Most are 1 to 3 feet away from the mark but sometimes further.

 

You can search the Geocaching data base of benchmarks here.

 

Another way to search is on the NGS web site under data sheets, radial search by coordinates or by county. Use "Any Horizontal Control" option.

 

 

Thanks for the info. The witness post was the kind of mark I was looking for. Something simple and bold he could find easily if I gave him accurate coords.

[+Woodstramp]

bye

 

I don't understand your post here, but thanks I guess.

[+Woodstramp]

Look at this one. It is located just south of Wright, WY. PID# OU0396 It is a WYOMING HIGHWAY DEPARTMENT "disc". The coordinates should take your brother right to the "Triangulation Station Disc".

 

Here is something similar to what he might see. I have posted one of our finds since none of those around his area have been recovered by any of the benchmark hunters from GC.

 

His will be "IN THE TOP OF A SQUARE CONCRETE POST". Where this Arizona Dept. of Transportation disc is in the top of a round concrete post, shown here...

 

 

Hey, Someone needs to recover all of these virgin marks! To see an area where the marks have not been reported on, seems to be an sin of some sort. Right?

 

I hope this helps some.

 

Shirley~

 

Thank you Shirley. I'll send him one of your pics to show him what the Wright BM you listed might look like.

[Papa-Bear-NYC]

Thanks for the info. The witness post was the kind of mark I was looking for. Something simple and bold he could find easily if I gave him accurate coords.

Just to emphasize, a witness post is not a marker and there is no accurate location attached to it. It is a sign that a surveyor stuck in the ground near a real marker (which is typically a disk set in the ground or on a building). The "real marker" (in other words the disk) is the thing that may have en accurate location as described above. The witness post is "near" the real marker, but that could mean anything from 3 feet to 30 feet or more, depending on where the surveyor could find a place for it where it would not get knocked down, stolen, etc.

 

So you should not be looking for witness posts, you should be looking for the markers that they bear witness to.

 

It's sort of like a sign saying "Slow, Children Playing". You don't look out for the sign, you look out for the children.

Edited May 20, 2008 by Papa-Bear-NYC

[+Woodstramp]

 

So you should not be looking for witness posts, you should be looking for the markers that they bear witness to.

 

It's sort of like a sign saying "Slow, Children Playing". You don't look out for the sign, you look out for the children.

 

Papa Bear,

 

My reasoning for posting this thread was to get help in locating easy targets for my (newbie to GPSing) brother to find with his new Magellan. I pre-loaded his GPS with some landmarks I found. Some are land features I found with Google Earth and some are Geocaches. I wanted to add a couple of BMs for variety. I'm not real swooft at Benchmark hunting myself , yet, so I figured there's be some veterans here that could locate a couple of easy ones for him. I had unsuccessfully attempted finding BM's myself a while back and some folks here kindly put me on one that just happened to have a nearby witness post. That really boosted my confidence in my GPS unit. A loud, nearby marker like that would make a good first reward for his effort instead of trying to locate a real benchmark disc that may be buried. He's just now learning how to set waypoints and doing GOTO's so I'm trying to help him with some easy pickings.

[Papa-Bear-NYC]

Papa Bear,

 

My reasoning for posting this thread was to get help in locating easy targets for my (newbie to GPSing) brother to find with his new Magellan. I pre-loaded his GPS with some landmarks I found. Some are land features I found with Google Earth and some are Geocaches. I wanted to add a couple of BMs for variety. I'm not real swooft at Benchmark hunting myself , yet, so I figured there's be some veterans here that could locate a couple of easy ones for him. I had unsuccessfully attempted finding BM's myself a while back and some folks here kindly put me on one that just happened to have a nearby witness post. That really boosted my confidence in my GPS unit. A loud, nearby marker like that would make a good first reward for his effort instead of trying to locate a real benchmark disc that may be buried. He's just now learning how to set waypoints and doing GOTO's so I'm trying to help him with some easy pickings.

I think your approach is good and certainly a witness post is useful for this excercise for the very reason it was put there, namely it is prominent and visible.

 

But there is a next step when your brother has mastered these steps of using the GPS, and that is to find the things that we are after, whether it is a Geocache or a benchmark. When you get to that point then the witness post becomes a helper, much like the clues in the GC descriptions or the GPS itself. Namely, these helpers get you close, but the final search is up to you to find the actual Cache or Benchmark. So if the description says the Cache is under a rock, or the BM is on a certain building or near a witness post, first you find the rock or the building or witness post (that's the easy part), and THEN you go that last step and find the actual target.

 

So keep up the good work with your brother and have fun. That's what it's all about.

Edited May 21, 2008 by Papa-Bear-NYC

[Wintertime]

I had unsuccessfully attempted finding BM's myself a while back and some folks here kindly put me on one that just happened to have a nearby witness post. That really boosted my confidence in my GPS unit. A loud, nearby marker like that would make a good first reward for his effort instead of trying to locate a real benchmark disc that may be buried.

You'll want to make sure, then, to read the description of the mark's location and select marks that actually do have witness posts, as most do not. Also, even if the datasheet says they do, the posts may have disappeared over the years. Your best bets, therefore, will be marks placed (monumented) within the last 10-20 years. Luckily, those are also the ones most likely to have adjusted coordinates.

 

Absent a witness post, look for marks that have easily identifiable locations--something easier than "in a concrete post at the edge of a field.".

 

Patty

[Bill93]

Sometimes the description for a disk in a concrete post says "projecting 6 inches" or such. That means, barring dirt work since the report, that no digging is required.

[+Woodstramp]

Thanks Bill, Patty.