Bill93

Intersection stations are ADJUSTED locations, meaning more accurate than your handheld GPS. Set a GOTO for the coordinates and make sure that it points to the tower as you walk around it, within the accuracy of your unit (a few feet under best conditions), as well as checking the descriptions.

I haven't checked out the laser device you mentioned, but would look really closely to be sure it was a laser measurement and not an ultrasonic measurement with a laser pointer to help aim it. If ultrasonic it is going to pick up a lot of obstacles and false ranges.

I've been surprised how bad reception is in the woods in the winter when all the leaves are off. Reflections still seem go cause readings that move 30 feet when you moved 10 and vice versa, despite stronger signals. Not the kind of behavior seen under clear sky. In summer it seemed more reasonable to have problems with trees. Have you noticed this effect on professional equipment, without the leaves? Is it something that averages out in a long reading period?

How far do you go? You are limited only by your perseverence, the laws of physics, the need to avoid making people mad and/or getting arrested, and the need to avoid any damage that a sensitive conscience should feel guilty about.

So the observation would be that officials are less likely to question the intentions of someone who looks like he is doing serious physical work? The problem with digging is that you need to be very aware of any buried utilities around. Some of them (like a lot of telephone wire, cable tv coax, and one fiber cable I know of) are not as deep as you would wish. Check for signs up and down the road before you dig. If I can do the job with a garden trowel I don't break out the shovel figuring I'll be less likely to do damage with hand power than foot power.

On TK0250 I agree that the GPS is your best resource to start out. The location is adjusted, not scaled, so it is very accurate. Do everything you can to squeeze accuracy out of the handheld. Make sure it has been tracking its location for a while so that it is sure of its time. Use fresh batteries. Hold it in the best position for its antenna. Use WAAS. Let the unit average for a minute or two. Go back on several days and put a stick in the ground where it says the position is on each day, then take the center of those points. Once you are confident of your readings within a few feet, measure from the center of the RR. You should be able to figure out whether the distance matches better measured perpendicular or straight east, and then use that direction to pin it down a little tighter. Be aware that railroads do sometimes move a foot or two as they are maintained over the decades. My first guess would be east, but I've seen quite a few marks that were described assuming the railroad always went in its predominant direction and never curved, regardless what a compass would say at the benchmark location.

>lots of room for TravelBugs I couldn't tell if you were joking. This is a BAD idea. BH

Frost isn't the only thing that moves benchmarks. I though GH55 was going to post this one but I haven't seen it so will supply a link: MH0498 being lifted out of the ground by a vine root.

>They're restationing the mark I would hope they restamp it RESET and send the new information to NGS.

My detector is a middle model of the Radio Shack line that I picked up at a garage sale. It is very adequate for finding a disk under a few inches of dirt, and easy on batteries. I use the old batteries that no longer operate the GPS and it just goes and goes. Whatever you get make sure the audio has some variable characteristic like pitch or volume as you sweep past an object, not just a two-state tone-no tone indication. There is a lot to be learned from more subtle changes in the signal. The main reason for headphones is so you can hear the detector clearly when it is windy or near traffic.

The DD MM SS.S format is great to work with, except that it has the poorest precision of the 3 formats available on most handheld units. DD MM.MMM is in the middle and DD.DDDDD has the smallest increment. All are better than the usual measurement accuracy, so it isn't a big deal, but if I'm trying to refine my measurements by averaging readings taken on multiple days then I use DD.DDDDD, manually average them, and then convert the average to whatever format I want to report. I don't want any more roundoff error than necessary. The measurement errors aren't random enough over a period of minutes so that averaging in the unit gets that kind of accuracy, but I'm hoping that the errors of a bunch of short term averages taken on different days will be uncorrelated so that I could get into the region where it matters. I've used this technique a couple times and have one mark that I don't get to very often that I'm still trying to improve my measurement on. I'd like to get to SS.SS with it.

Start with the descriptions on the original triangulation station DX2175 SIER. To get the data sheet from NGS site you have to click the "include destroyed" box. It only has location to whole seconds, since it isn't being updated like current marks. To that accuracy, its location is the same as AA7647 SIER RESET. DX2175 has various descriptions of where RM3 was located. It says it was stamped SIER NO.3 1928 1933. I think regardless of what you find in its neighborhood, if it doesn't have that stamping or you don't find a note saying it was re-stamped then you haven't found it. Those descriptions include statements that it was at (1971 adjusted) elevation of 2989.33 ft. Does that check? Those descriptions also say 3/8 mile from the triangulation station. It seems like 3/8 mile direct could match up pretty well with 0.55 on the trail. The direction was given as S 57 deg 47 m E, which is moderately close to Az 122 10 45.5 CC3821 SIER RM 3 AZIMUTH does not have a real data sheet, but does get a nominal coordinate listing, which is probably SCALED and thus not of much value in pinning down the exact location. Those numbers that look like PIDs but do not fit in the old grid numbering scheme for PIDs (now abandoned for new marks in favor of the AA type numbering) are almost always a designation for a reference mark that is not by itself geodetically controlled. Using the NGS utility program FORWARD.exe as found on their web site to do the precise geodetic calculation, starting at the triangulation station at N33 51 00.54 W117 39 13.29 and going a little more than 3/8 mile (=603.5 meters but I picked a distance closer to your mystery disk) 628.7 meters at az 122 10 45.5 you end up at coordinates N33 50 49.7 W117 38 52.6 which is within handheld accuracy of the disk you found. The distance is a lot cruder than the angle, so if you set a goto on those calculated coordinates and search several feet either side of the line where your GPS says the goto bearing is 122 or 302 degrees you would be looking in the right place. So I agree RM3 is/was very close to 3R-78-71, but I would say you can't assume somebody replaced it unless you find a record. There could be two marks in close proximity here. Re-read all the data sheets again for clues we've missed.

I find BDT's simple format agreeable, but would think it should be reported to 0.1 second, since your handheld on a good day is quite a bit better than a whole second. BH

I've been looking for a 1934 elevation mark NJ0539 along a former railroad, now a trail. Today I went back and with the grass down I easily saw a concrete post lying on its side. It is about 135 feet from where I expected to find it and 250 feet from the scaled coordinates. I couldn't identify the hole it came out of--it could easily have been several years since it was uprooted. There is an outline of part of a circle where the disk was. It appears that someone broke one side out of the post to extract the disk. Of course we can't tell for sure it was the mark I was looking for so I'll have to report it to NGS as NF, but I'm sure enough that I logged it on GC as destroyed. There is a CGS and State Survey disk (not in NGS data) about 0.2 mile in one direction and a 1966 USGS disk (not in NGS data) 0.6 mile down the trail, so the area has been well covered. Is there anything we can determine from the remains to help decide that it is or is not consistent with the 1934 marks? I'll try to get pictures posted here eventually. It appears that the top foot or so was formed, and the rest was poured into an unformed hole. This might be how much stuck out of the ground. How do you date concrete? There might be a remnant of the disk's shaft still in the post. Would extracting that help decide if it was a 1934 US CGS disk as opposed to USGS or other agency? Any other ideas?

KU4000 location is ADJUSTED. That means coordinates more accurate than your handheld GPS--within inches. Set a GO TO and walk around to see where it points. Is the building there of sufficient age and apparently unmodified since the date it was described? Is there an obvious point to sight on at the top of the building?

I'd say log it on Groundspeak if you can see it, it fits the details of the description, and you get a "go to" to point accurately to it from a couple widely separated angles (ideally one N-S and one E-W).

On the mark that is listed as 3000 when it was expected to be nearer 1000 ft, 938. (meters) 3077.42 (feet) it seems likely that the elevation was supposed to be 938 feet and got its units converted once too many times. Since it is a horizontal control point, the elevation doesn't get much scrutiny. I think I recall another example of this being discussed.

If you have decent coordinates for the mark, I don't see that you usually need to worry about the "to reach" description at all, much less coordinates for locations along the way. Just get within some yards of the coordinates by any legal route, and then look for things to measure from.

NGS initials : Geocaching name ------ ---------------------------- BDH: Bill93 GJA: 299792458 Gerard Ashton MPR: or MR: (on some reports) elcamino TAK : Black Dog Trackers

I would be satisfied to let those who want points play the geocaching and benchmarking games on Groundspeak, and let the NGS do its own thing, which is continuous improvement of the data base. I get the bigger charge out of seeing the submissions show up in the data base. Rather than tie up DaveD, Casey, and the other staff with going through beaurocratic hoops regarding policies, privacy, awards, etc., etc., and writing programs to sort statistics they don't need, I'd rather see them working to put photo links on data sheets, and correcting the more difficult backlogged problem submissions.

A VOR or VORTAC station is probably not what the old references to beacons are talking about. PG1665 mentioned above is a light on a steel tower. I was also thinking beacon might sometimes refer to low frequency radio beacon towers. Any station described before the early 1950's would definitely not be a VOR. And I don't really like the idea of having a cache close to one of the FAA's important pieces of property. Maybe out in the boonies no trouble will come of it, but it is not much different than airport perimeters if somebody official sees you there.

Some of those should be findable without a metal detector, since they are adjusted locations and some have decent ties that might still be identifiable 35 years later. For those, I'd go to where the coordinates said, figure I was within whatever tolerance the GPS unit indicated, and pick out the landmarks for measurements. If you can find the things to measure from, that ought to get you within a foot. Since I have a metal detector, I would use it next. But if I didn't have it, I would probe with my dandelion digger to see if I could find the rod a few inches down. The one 13 feet from the center of the road may be a problem. Depending on the road that may put it in the shoulder or in the traveled portion. If it is under pavement, you'll just have to note the fact and forget finding it. It originally was probably set at the edge of the gravel or outside the pavement. If they reworked the road in those 35 years then it is probably wiped out. If still gravel, you may still be able to find it but it wouldn't be nice to dig too much of a hole in the road. Again the metal detector would help. Some of those marks may not have careful enough tie measurements, or enough preserved landmarks, to get you that close, so you could need to search several feet around the nominal position. Then the metal detector would really help. Since re-rod is often used to mark land corners, be very slow to claim what you found is the right one and confirm it by the most accurate GPS and tape measurements you can make. If you can identify the land corners by fence lines and roads that will reduce mix-ups. Add to your list of things to carry: a nicely printed copy of the data sheet. It helps convince neighbors and deputy sheriffs that you have some peaceful purpose (however weird) for being there. And be very careful about digging alongside road right of way and yards. The trowel or dandelion digger, gently used, is slower but much less likely to cut a cable than a shovel (even small) under foot pressure.

Before GPS they achieved super precision with super human efforts using high grade theodolites (on towers as needed) and massive amounts of office computation to adjust the data until all the measurements fit as best possible. There is some good history somewhere on the NGS site.

We were once told to submit reports to Cheryl instead of Deb but some people still refer to sending to Deb. Could we get a re-iteration of which person deals with which kinds of submissions?

When the face of a disk has been damaged but is solid in its mounting, how well can the surveyor reconstruct the position? If the circumference is well defined and undistorted is that adequate to define the center position even if the original center mark is obliterated? If the disk is for elevation, I wouldn't think you would care much about a center mark. The important property is the height of the domed disk. But how hard will the surveyor work to measure the amount of height removed from a scraped disk like LE0221? (I reported this one as POOR). Part of the judgment on a damaged disk is whether it can be identified with reasonable certainty. I would contend that LE0221 can be identified because it is clearly a US CGS disk (and unlikely to have another CGS disk nearby that is not in the data base), is in the remains of the described bridge on the right road, and within the usual tolerance for scaled coordinates. I would not make a similar claim for an unreadable disk when looking for a USGS disk in a concrete post without very precice landmark ties.