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Nearby Pid

Harry Dolphin
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This is a loggable mark, however many of them are in protected, inaccessable areas. The station you're asking about is a GPS CORS station. CORS stands for Continuously Operating Reference Station and is only part of an intricate system of such stations. They run 24/7 collecting data on a particular point, and when that data is compared and used with data from other stations, very precise geodetic locations can be derived. The data from these stations is used by surveyors, geologists, the FAA, and anyone who requires very accurate GPS readings.


If you can find the station and/or get to it, it would look like a large (about 2 meters high), survey grade, GPS antenna (like a large saucer or bucket on a pole). You'll know it when you see it. If you follow the coordinates, you'll get right to it. There are no coordinates more accurate then those from a CORS station.




For more info on CORS, see the NGS site Continuously Operating Reference Stations.


- Kewaneh

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My opinion is that we should not be attempting to recover any CORS stations. The pictures I've seen, like the one Kewaneh posted, show delicate equipment that we should not get near.


I think the best thing when finding one of these in a GC.com proximity search is to post a note saying that it's an inaccessible CORS station. That way, it's more likely that other searchers will see the note icon and move on to unlogged PIDs in the list.

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I think geocaching.com should try and do two things for CORS stations:


1) Log that they are inaccessable data collection stations, so the casual finder knows.


2) Where possible, take a picture of the antenna. Yes, technically you can't see the "spot" inside the antenna, but if it is visable from a nearby road or whatever taking a snap will complete the "log a photo" requirement close enough.

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I don't think eliminating CORS stations from the search and recovery that we do is necessary, for either the safety of the benchmark hunter or the safety of the equipment. It's true that many CORS stations are in protected areas, like rooftops. They are there for a reason, but the reason is usually for a clear view of the sky. Many of the rooftop antennas can clearly be seen from the ground. From a GC.com standpoint, these should be treated similar to a triangulation station which is a radio tower, church steeple, or smokestack. We don't have to get near them to see them and know that they are there, and technically recover them.



This one is located on top of Douglas County's Courthouse Building in Roseburg Oregon.


Also, there are quite a few CORS stations that are out in the open and easily accessable, they're just usually not in high-traffic areas. They get placed on college campuses, near fire stations or ranger stations, in highway medians, or any other place that may be a relatively controlled environment where the station can safely do it's job. The general public just doesn't particularly know what they are and they get left alone. Any CORS station like this could be an easy and safe recovery. That being said, they do occasionally get vandalized. Early last week one of California's Plate Boundary Observatory's GPS Stations was vandalized and the GPS receiver was stolen. (See the San Joaquin Valley Chapter of the California Land Surveyor's Association website.)


For those who may be interested, the Ohio DOT has a good page on their website showing the construction of a CORS station from start to finish. The station they've built is a ground-level, free-standing antenna with none of the electrics and mechanics (except the antenna) exposed.


- Kewaneh

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I feel that pictures of sensitive controls should be kept in (my file).


GPS and CORS pictures will not be placed in a public place by me.


If you want the pictures of the one's I have feel free to e-mail me.

I only have a couple of them anyway.

The things I had to go through just to get to the site is enough for me to know,they are sensitive.



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Kewaneh -


I see what you mean now. The one picture looked as delicate as someone's camera on a tripod but I now see others that look secure enough. I searched the GC.com site for "CORS" and found several finds already for CORS stations. Most have no picture, but there are a couple of pictures.


For logging, I'd suggest the same thing applies to these as for intersection stations - take a picture if you can see it but you don't have to get right on top of it, nor do you really have to find out if it is running.

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GPS and CORS pictures will not be placed in a public place by me.



I respect your decision to do or not do what you want with your photos, but it does strike me as somewhat extreme.


These CORS stations are not (as far as I know) related to national security in any reasonable way. Their location is hardly secret. NGS, in fact, has photos of some of these installations on their website, e.g. AF9522 (CORS station GAIT). antenna_gait_06.jpg

No, al Qaida and company probably don't surf the NGS site, trolling for targets. But I'll wager they don't spend much time at geocaching.com either.


It's bad enough when our civil liberties — including the freedom to go places without being questioned, frisked or X-rayed; to take photos of civil engineering structures; etc. — are increasingly curtailed, all in the name of that most amorphous of all excuses: "security." It's worse when we voluntary hand in those liberties.



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I feel a geocacher could ask to recover the station from the department which has the station in operation. You never know, you may get ushered to the roof with a full on explanation of how it works. It is the heart of control for all the survey in the area, and the keepers of these stations take pride in the accomplishments and their local programs. It could be an enjoyable time for all.


Some county sites have a lot of data on line for their control. You never know, you might enjoy inquiring. You might be surprised that they are enjoying that you have taken interest.


Here is a methodology we use to determine the ARP, or the HI; Height of Instrument with GPS:




Good Luck,



Edited by evenfall
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