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Bill93

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Everything posted by Bill93

  1. If you are looking for more search targets because you've pretty much exhausted your local area, you could try this list https://www.ngs.noaa.gov/OPUS/view.jsp This is a secondary list maintained by NGS, which accepts submissions of 4 hours+ of data from professional GPS units along with descriptive material and pictures. It takes much less effort than getting one into the main NSRS data base. This list includes submissions for the "GPS On Benchmarks" program which provides checks on GRAV-D. There aren't a lot of them in my area. I've mentioned in other threads (e.g this) how I have been using a nearly antique professional GPS receiver, and now I've submitted a few sessions to this data base. The one I consider most important fills a gap in their coverage of stations having both old leveling data and GPS observations. I also did a check on a point submitted by DOT, one on a reset disk that probably isn't so important, and got a new point entered for a USGS disk I happened across that's in a very nice accessible place so others might want to use it.
  2. I think Kayakbird has it: "it appears to me that the original 1934 has been slightly modified to 1954. My idea is that the post earthquake visit saw no reason to do a full reset" Compare the stamping of the 3 on N 46 KQ0340 The pictures have to be of the same disk. Someone didn't bother to figure out which mark they found when they went to log. Nobody has actually logged RM1 on geocaching.
  3. I suspect that you found KQ0480. Check the stamping carefully to see if it matches https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=KQ0480 I'm puzzling over this mess, and the picture is still cloudy. Key to it all may be the latest NGS data sheets and comparing them to the ~2000 sheets captured at Geocaching, as some editing has been done to the entries before 2000 as well as adding newer recoveries. NGS even says that the trail isn't clear. There was a 1934 series 46 as shown by nearby disks. Disk M 46 KQ0337 may be gone. The recoveries at https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=KQ0480 show somebody went out and measured this disk in 1954 by triangulation and leveling, as both horizontal and vertical are ADJUSTED. Perhaps they created confusion by re-using the designation in 1953 when they placed a new disk for this measurement? They would have set RM 1 (KQ0335) and RM 2 (KQ0336) at that time 1953/4, as I've never seen a RM for an elevation-only mark. I'm guessing someone worked up ADJUSTED elevation data for RM 1 and RM 2 from the later leveling (see GC data sheets) but then decided it wasn't accurate enough in relation to M 46 (1954) because they were so close together the standard tolerance would be very hard to meet. On recognizing that, they were downgraded on the later data sheets. Note that the GC log and photo for KQ0335 do NOT show the stamping RM1 which is called for, so it was probably KQ0480 they found. I'm a bit puzzled where the HH1 coordinates on the RM's came from. The didn't come from a sportsman's HH2 GPS receiver and there is no recent recovery, nor any OPUS Shared Solution for them. Hope that heads you in the right direction to figure the rest of it out. Argue with me if you don't like my reasoning.
  4. Right forum, but there's a New Topic button. What about distance measurements? Is it the right distance from a road, right height from road, right size rock, and right distance from highest point? The X certainly doesn't sound right for a stem remaining from a disk.
  5. Your question should have been in a new thread instead of hijacking this one. But since we're here ... Coordinates were scaled, and could easily be 100 ft or more off so they don't prove anything. The disk had stamping on it (4032.531 U 327 1953), and was not just a rod. If the object you found looks like a stem with the disk pried off of it (torn metal), and all the distance in the description check out, including 6 FEET ABOVE LEVEL OF ROAD, then you have a FOUND POOR. Also look for a depression cut in the rock about the diameter of a disk, which would often be made to seat the disk solidly against the rock. I don't see that clearly in the picture. If this is a nice uniform undamaged brass rod, which the picture sort of suggests, or the distances don't make sense on that rock, then it is somebody else's mark and not the one on the data sheet, so if you looked very thoroughly at those distances then I'd log a NOT FOUND.
  6. I have a theory that those folks had to turn in a sheet with check boxes for Found and Not Found, with no option for "didn't have time to look" or "didn't look hard."
  7. 1. How does Groundspeak get the BM coords? They got a snapshot of the National Geodetic Survey data base in about 2000 or 2001. They appear to not plan to ever update that. The information is still available from NGS but not in the exact form they used back then as a compact disk. 2. How are cachers notified about where BMs are located? Search options at https://www.geocaching.com/mark/ or "Nearest Benchmark" on cache pages. 3. What process do cachers use to show that they have found a BM? A log just like for a cache, except that they are encouraged to not be secretive. It is good to give updates to the to-reach, coordinates if the original ones were scaled and far off, and pictures. 4. What credit do cachers get for 'discovering' a BM? They do not count toward cache find totals but are reported separately.
  8. Some marks I reported via web form in 2016 have now been updated, some time in the last week I think. They are working off the backlog or perhaps are caught up now. Hurrah!
  9. I live in Cedar Rapids. Was it a family or business visit? If you get out this way again, send me a message.
  10. I didn't get that sense at all. They give pretty basic instructions to both pro and amateur. And reading recovery reports on the data sheets, I see examples where some people in each group need detailed advice. Not all the reports are up to high standards. There was an extreme example, where a cacher posted that NGS needed to move the disk because it wasn't where his handheld GPS said it should be. That got a lot of laughs from the pros and downgraded geocachers' status in their eyes. That person could have used a little education on what was going on. Looking at the recovery notes posted on the GC pages, I shudder to think someone might log to NGS with comments like "Found in the rain with my cousin BeetleBrain while visiting Grandma on vacation." A little reading on the NGS site may help people get a better perspective. Even people working for survey companies sometimes post poor reports. They seem prone to posting Good with no update to ties in a much-changed area, or a NF because they haven't thought out how the 1934 situation relates to today's situation. One I found last week had a 1999 report by someone from a big company that said they found a culvert with no disk, when I found the proper culvert with disk within yards of the published coordinates. That shows a hasty look with too little thought. It's possible that the disk was covered with dirt at that time, but it should have been obvious there was a culvert to investigate. So I'd say read the site, and if you already know the material, good for you, but most of us could learn something from it. ------- No offense intended if someone uses the handle Beetlebrain. I just pulled it out of the air.
  11. I noticed that NGS has a good and fairly detailed tutorial set of pages on bench mark hunting and reporting, that has been recently updated. It has advice for both geocachers and professional surveyors. https://www.ngs.noaa.gov/GPSonBM/
  12. Yes. You must provide the height in meters above the mark to the antenna reference point (ARP) when submitting to OPUS. I calculate that by measuring to the rim of the ground plane and solving the right triangle to find its height then subtracting its height above the ARP. Actually I made a table with a spreadsheet and pasted it in the back of the field book. Some manufacturers have all that built into their own processing software so you just give their program the slant distance, but OPUS doesn't do that. OPUS does look up the antenna type you enter and takes care of the antenna phase center relative to the ARP. That value is different for L1 and L2 signals and even for different elevation angles from the satellite, but they have calibration tables for dozens (hundreds?) of different antenna models so you don't have to worry about that. I ran sessions on 4 marks to compare with other peoples' GPS height values before I convinced myself I had it right. The first three all came up a cm or two higher than the other peoples' values and I was worried I had it wrong, but finally decided that was just the roll of the dice. Typical vertical repeatability for 2 or 4-hour sessions is in the very few cm range. Horizontal is tighter.
  13. I haven't been getting out much lately, so took Friday to go hunting in superb weather, and had a good day. -Found Good, one that was last reported in 2006. I ran a 6-hour GPS static session and expect to submit a Shared Solution to the GPS On Benchmarks program. -Found Good, one that was last reported as probably destroyed -Found Good, trivially easy one last reported in 2006 -Found a stem where I expected a RESET as MH0029, but hadn't read the data sheet for the original and now am confused. I have to go back to see if this was perhaps the original. -Tried to find one on an abandoned bridge, but was defeated by 18 inches of dirt, ballast rock, and roots on the old bridge deck. It is likely there under all that. ----------------- Last reported as NF probably destroyed (obviously I didn't need the metal detector) GPS set up:
  14. Anyone seen any of their pending reports posted? I haven't.
  15. The professional surveyors forum has an interesting post summarizing a recent conference at NGS. It helps understand where NGS is headed, and why bench marks, although still useful, will be less important after 2022. Basically, there will be no more updating of passive mark data sheet coordinates or elevations, as has been done in the past from NAD27 to NAD83(86) to various realizations up through NAD83(2011). The most accurate measurements will rely on GPS measurements and a gravity model derived by the GRAV-D program. It will take a while for various users to switch over, so they will still need the passive marks for a while. Look at the Corps of Engineers - many of their projects are still on NAD27. Some cities are still on NGVD29 elevations.
  16. I inquired whether the backlog would be processed or lost and got this reply: Hi Bill, As soon as this problem is resolved, I'll process all backlogged recoveries immediately. I'm very sorry for this delay but at the moment, there's nothing I can do personally. Thank you (and all the folks) for your patience. Deb
  17. On the Surveyors forum there is a thread about a 1930's very difficult to-reach description out in the wilds of Utah. Nowadays it must be relatively easy because there are multiple GC recoveries for it, beginning with our 2OF Rockhounders. What's the most difficult description you've come across? What's the most difficult you've actually followed?
  18. They are testing a beta release of an interactive map that lets you see the actual linkages in the triangulation networks, and the general route of leveling by both C&GS/NGS and USGS. https://beta.ngs.noaa.gov/gcd/
  19. So does that mean we wait for notice that it is working (and how do we get notice?), and then re-submit anything that hasn't appeared, or will they find things already in queue to process?
  20. I don't think I've posted this before. Someone took a few pictures while on a trip and another added more. There are more property corners than geodetic marks, but some of those, too. https://rplstoday.com/community/threads/japanese-corner-marks.325399/
  21. If you've found a disk by accident and want to find a PID and data sheet, start here https://www.geocaching.com/mark/ pick Advanced Search Enter approximate latitude and longitude and search. If that comes up with something near, compare the agency name and stamping to see if it is the one you found. You can do something similar on the NGS web site, which may have new marks added since the Geocaching snapshot of their data base in about 2000/2001. With a US Geological Survey disk, the odds of it being in the National Geodetic Survey data base are small but significant. Only some fraction of those were measured to the standards and included in the NGS list. The USGS list is on paper in file cabinets and will never be on line, and they don't care much about recoveries.
  22. This seems to be targeted at students in surveying and GIS programs, but I'm not sure it's limited to those. Applications close Feb 2. Find existing 1968 bench marks, run static GPS sessions, and report. http://ak-aug.blogspot.com/ Participants will engage in benchmark recovery, which includes: Reconnaissance: locating NGS passive control monuments via GIS and field work; Recovery: executing survey of recovered benchmark with proper documentation for submission to OPUS shared solutions; Report: submission of findings to NGS and DENA GIS Specialist.
  23. Yes, I should check out the other processing options. Doesn't OPUS Projects require simultaneous measurements at multiple sites? I only have one good setup. I'm using a tripod and tribrach. I measure up on 3 places to the ground plane to check centering/leveling, and calculate back to ARP height above the mark. I've pasted a spreadsheet in the back of the field book to quickly give me the difference. I don't think I have any problem with repeatability of setups, because session results seem to match as well as the pk-pk values of a session. Fixed height would avoid the calculation and chance of blunder there, but would require me to get more hardware and figure out how you make it stable. It seems like you would either need a sliding sleeve for the rod if using a tripod (4 legs aren't stable), or have to be careful at balancing and carry weights with a bipod.
  24. Last year I acquired a Trimble 4000sst receiver and accessories. It has gotten me some interesting measurements, but doesn't qualify for the NGS program for GPS on Benchmarks because it doesn't process enough parts of the GPS signal. Recently, I bought a slightly newer model, the 4000sse, which uses all the old accessories and does qualify for OPUS shared solutions which can be used for the GPS on BM program. These receivers can be bought on eBay occasionally for a few hundred dollars, but you need to know what all is needed in the kit and to distinguish the reasonable models from the totally obsolete. Here's the setup on a tri-station with old receiver. The newer one doesn't look much different. For those who don't know about OPUS, here's a summary: The receiver records measurements every 30 seconds, and stores them essentially as a time delay from each satellite in view. You download those into a computer file and after some waiting time for CORS and orbit data to be collected, you send it to a web site at NGS. They automatically process this against CORS station data. A few minutes later it emails you a report that tells you where you were and some measures of performance. The orbit data is either "Ultra Rapid" meaning relying on predictions and available within a few hours, "Rapid" meaning updated with real measurements the next day, or "Precise" which has been processed to the best possible estimate but 2 to 3 weeks after the fact. There are two processing options, OPUS-S or static for 2 hours to 48 hours, and OPUS-RS or rapid static for 15 minutes to 2 hours. The RS algorithm is better in some ways and lets you get away with the shorter sessions for some uses, but OPUS-S with at least 4 hours is needed for any NGS use of the data. I'm hoping that when the weather warms up I can do some OPUS shared solutions on benchmarks that NGS can use as they check their gravity model. I want to have checked my results on a couple HARN stations first. Today I got the results using final "precise" orbits for a 7-hour session on a point in my back yard, processed by OPUS-S and also split into 7 sessions of 1 hour each for OPUS-RS. Here are some plots I put together to compare results. There are effects that the processing doesn't know about, so the supposed 95% confidence limits only apply to some of the error sources and can't be taken at face value. But note that the horizontal grid is 1-cm squares and the vertical grid is 2 cm. All of the horizontal position outlines would fit comfortably on a US 5-cent piece.
  25. A lot of work went into this project by Jerry Penry, Kurt Luebke, and friends. Introduction & links Survey discussion and pictures Wikipedia for background info: https://en.wikipedia.org/wiki/Black_Elk_Peak
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