DaveD

Excellent job BILL93. I have received the observational data from LOOMIS to BOWEN from NGS and computed the position to be 38-57-19.0546, 77-08-55.7080

Seth, you can the original field observations to me at -- base9geodesy@gmail.com

It was not unusual for NGS field teams to observe intersection stations (towers, tanks, church steeples etc.) even if they didn't have their own position. Remember this is before GPS and one of the functions of these marks was to provide position and orientation for surveyors to begin or end other surveys. The tanks could have been used for orientation. Without seeing the field work I can only guess at what he did there.

I doubt that this station will be added to the active database. NGS does not just publish descriptions of stations, they must have a well determined horizontal position and/or a well determined orthometric height. While the field observations that were performed to set this station were more than acceptable 30 years ago in all likelihood they don not meet the contemporary requirements. The horizontal position would have been determined by the standard process of performing a traverse not using GPS. NGS stopped including non-GPS derived horizontal positions in the mid-90s. Since there were probably no high accuracy leveling observations performed the station would also not have a well determined height. Unless someone can perform some GPS observations on the station and submit them to NGS this mark will likely remain an orphan.

Skintigh - I've been in contact with the NGS Information Center. After a bit of over the phone hand holding I was able to lead them to where the data for station BOWEN had been archived. It was where I had assumed it would be. If they have not already done so, they should be able to provide you with the description of the station and the position. As it is on the CIA campus that does mean that access to the mark is most likely highly restricted.

The 1984 recovery for station LOOMIS (HV4826) was submitted as part of the now defunct NGS Mark Maintenance program - this is identified by the initials of the chief-of-party of the submission (CLN) - Mr. Charlie Novak. At the time the data for new station BOWEN was submitted to NGS headquarters the agency was in the final stages of building the initial automated control database (the first of it's kind anywhere in the world). The reason that this station does not now appear in the NGS database is probably one of two - either the procedures that the field person used did not specifically meet the newly implemented requirements for being loaded into the DB or it was just not automated. The field data for this station should still be in a folder in the NGS offices today. Anyone interested in more information on this marker should contact the NGS Information Center - ngs.infocenter@noaa.gov and specifically ask for these data by the name of the station and that it can probably be found in one of the Mark Maintenance folders for the state of Virginia in the NGS archives room on the 8th floor of their building. It should only take a few minutes for someone to find and review those folders to see what's there.

The control stations with the most accurate coordinates are the network of Continuously Operating Reference Stations (CORS) managed by the National Geodetic Survey (NGS) - http://www.ngs.noaa.gov/CORS/. In general these stations have horizontal accuracies of right around 1 cm and ellipsoid heights at around 2 cm. As for 1st-, 2nd- or 3rd-Order horizontal stations these are now at the lower end of the accuracy chain in the National Spatial Reference System and should seldom be used for anything that requires high accuracy. With the completion of the national adjustment of all the GPS stations in the NSRS by NGS in 2011 (NAD 83 (2011)) those stations are no longer classified with the old proportional accuracy statements. Rather they are given their positional accuracy in horizontal and ellipsoid relative to the entire network. For examples station CS2783 (NEWTON) has a network accuracy of 0.9 cm in the horizontal and 1.4 cm in the ellipsoid height. BILL93 is correct that this student needs to determine if the accuracy is required to be local (all of the U.S.) in which case he should use the NAD 83 (2011) coordinates, or global in which case he should use ITRF coordinates. He can access these data by going to the NGS home page www.geodesy.noaa.gov and then selecting "Survey Mark Datasheets" on the left side. There are several ways to access control. Once he's got an idea of the area he wants to search he should limit the search under "Data Type Desired" to "GPS Sites Only." If he has any problem accessing these data and/or understanding the geodetic elements on the datasheet I would be happy to discuss these issues with him -- base9geodesy@gmail.com CS2783 PACS - This is a Primary Airport Control Station. CS2783 DESIGNATION - NEWTON CS2783 PID - CS2783 CS2783 STATE/COUNTY- TX/DALLAS CS2783 COUNTRY - US CS2783 USGS QUAD - FERRIS (1968) CS2783 CS2783 *CURRENT SURVEY CONTROL CS2783 ______________________________________________________________________ CS2783* NAD 83(2011) POSITION- 32 37 06.48374(N) 096 44 09.28934(W) ADJUSTED CS2783* NAD 83(2011) ELLIP HT- 148.888 (meters) (06/27/12) ADJUSTED CS2783* NAD 83(2011) EPOCH - 2010.00 CS2783* NAVD 88 ORTHO HEIGHT - 175.23 (meters) 574.9 (feet) GPS OBS CS2783 ______________________________________________________________________ CS2783 NAVD 88 orthometric height was determined with an earlier geoid model CS2783 NAD 83(2011) X - -630,747.576 (meters) COMP CS2783 NAD 83(2011) Y - -5,340,407.498 (meters) COMP CS2783 NAD 83(2011) Z - 3,418,476.319 (meters) COMP CS2783 LAPLACE CORR - 4.04 (seconds) DEFLEC12A CS2783 GEOID HEIGHT - -26.33 (meters) GEOID12A CS2783 CS2783 FGDC Geospatial Positioning Accuracy Standards (95% confidence, cm) CS2783 Type Horiz Ellip Dist(km) CS2783 ------------------------------------------------------------------- CS2783 NETWORK 0.90 1.41 CS2783 ------------------------------------------------------------------- CS2783 MEDIAN LOCAL ACCURACY AND DIST (008 points) 0.97 1.39 30.51 CS2783 -------------------------------------------------------------------

A bench mark does not have to be found to have either an HH 1 or HH 2 position. First note that the NGS description of an HH 1 position is "The horizontal coordinates were determined by differentially corrected hand held GPS observations or other comparable positioning techniques and have an estimated accuracy of +/- 3 meters." Many marks were positioned by "other" positioning techniques. During my final three years at NGS I made an effort to harvest horizontal positions determined by the U.S. Geological Survey (USGS) for many bench marks for which NGS had only a scaled position. These data had never been submitted by USGS to USC&GS/NGS for inclusion into the national network but were none the less of at least third-order accuracy which more than meters the requirement for an HH 1 position. Unfortunately I was probably the last one at NGS who even knew these data existed and could still be of some use. Another set of marks that often had scaled positions were Reference Marks for triangulation stations that were also bench marks. It was a rather simple process to compute the position of RMs from the azimuth and distances provided on the NGS datasheets. These values also more than meet the requirement for HH 1.

NGS updates data in their database every day. New projects with many new marks and updates to old ones are constantly being submitted by professional surveyors for inclusion into the National Spatial Reference System. Those on this board can provide important updates such as current recovery information, submitting good quality digital images and adding hand-held GPS positions for those bench marks that have only a scaled horizontal position. The best way to do this is to use the DSWorld utility http://www.ngs.noaa.gov/PC_PROD/PARTNERS/index.shtml. Over the past several years I have personally harvested hand-held positions and pictures for more than 60,000 stations from this site. I have often been frustrated when I've seen someone post that the published scaled position for a mark was way off (several hundred feet or more) and then they never provide a more accurate value. While it's a little out of date because the interface as changed there is a nice webinar about DSWorld that can help you step through it's capabilities - it's really pretty easy to use -- My lihttp://www.ngs.noaa.gov/corbin/class_description/DSWorld_0212.shtmlnk

The Coast & Geodetic Survey (USC&GS) did a significant amount of geodetic survey work in the Bahamas during the 1960s as part of the U.S. space program. The country has lots of USC&GS triangulation, bench mark and tidal stations across most of the inhabited islands. Unfortunately these data were never automated and added to the NGS database. By the time the DB was created this effort was long past and since these data were not in the U.S. and were not going to be part of the North American Datum of 1983 or the North American Vertical Datum of 1988 they were ignored. They still have paper records so if you contact CO-OPS as ERNMARK indicated they should be able to dredge up the old data for you.

The difference between a height value that is Class II vs. Class I has to do with some fairly minor, but none the less important aspect of the leveling field procedures and final analysis. In practice the difference between any two nearby marks should be in the sub-mm range.

Absolutely the Jefferson Pier. If you a little sharp eyed you might want to look for A 8 (HV8076) and B 8 (HV8077).

Without knowing the bearings/azimuths/directions along the boundary and the corresponding distances it's not possible to validate any of the coordinates you posted.

On Friday, April 11 the North Carolina Geodetic Survey in collaboration with the NC Museum and Preservation Society, the NC Society of Surveyors and the National Park Service will host a dedication for an interpretative site for the Bodie Island Baseline. Observed in 1848 by the Coast Survey under the direction of Alexander Dallas Bache, it is the oldest complete geodetic baseline in the United States. The dedication is scheduled for 11:00am at the parking area approximately 0.15 south on Route 12 from intersection of Rt 64 in Nags Head, NC. The site is approximately 0.3 north of the location of station Bodie Island North Base 1848 (pid EX0456). For additional information see North Carolina Society of Surveyors

As noted by Bill93 without addition information there are different ways to evaluate this information. That being said, to one extent or another most of them would have differences that while significant interms of defining the boundary would be small compared to what can be observed with a hand-held resource grade GPS receiver. Based on the information you provided I calculate the approximate Point of Beginning as 19-13-28.2/155-52-27.4 or 19-13.470/155 52.457

Unfortunately I no longer have access to the original paper datasheets for these stations, none the less I have a pretty good idea of what may have happened here. It's not a clerical error, but rather a software error. These are all old USGS stations that were submitted to the National Geodetic Survey for inclusion in the National Spatial Reference System decades before there was an automated database. The directions from the station to the RMs is most likely correct on the original paper data sheets and were inadvertently changed when NGS completed the North American Datum of 1983 adjustment and developed the original architecture for the existing database. Among the various significant changes NGS made in the publication of NAD 83 was changing the orientation of publishing the geodetic azimuths from South to North. As part of that process software was written to search the now automated description data and change the orientation of azimuths imbedded in the text. In the case of these stations the directions to the RMs are in bearings not azimuths but may have been an unintended victim of the mass changes.

From the Office of Personnel Management (OPM) -- In a shutdown furlough, an affected agency would have to shut down any activities funded by annual appropriations that are not excepted by law. Typically, an agency will have very little to no lead time to plan and implement a shutdown furlough. That means all computer systems associated with those activities.

I regret that even most surveyors in the U.S. don't know that the datasheets don't exist until you request them.

I just finished posting this to a survey web site: I don't mean to be rude, but anyone who thinks the NGS database is nothing more than an autonomous computer sitting on a desk somewhere and can run without attention must still believe in the tooth fairy and the Easter Bunny. The NGS database, internally referenced as the IDB (Integrated Data Base) is without a doubt the most sophisticated relational survey database anywhere in the world hosting data on something like 1 million plus individual passive and active control stations. The "datasheet" that everyone is use to is not an existing product, each and everyone is computed on the fly in microseconds by a network of thousands of subroutines that select and validate the appropriate information for any specific request. Just as the various elements of the National Spatial Reference System require highly skilled, world class geodesists to collect gravity data, compute geoid models, manage the CORS network, develop and manage OPUS and the array of other geodetic utilities, so too the IDB requires constant attention from a staff of very talented and dedicated IT professionals. The database team and associated technical staff committees at NGS work very much behind the scenes, but I can personally vouch for their amazing dedication to building and maintaining the IDB and their service to the nation. In addition there are a host of rules that virtually all federal agencies must comply with in the case of a shutdown, among which are limiting access to federal computer systems without proper staff to monitor security and use.

There no real reason to submit photos and/or hand-held GPS positions for Reference Marks or Azimuth Marks unless they have either an ADJUSTED NAD 83 horizontal position (in which case you don't need the HH position) or an ADJUSTED NAVD 88 "ORTHO HEIGHT." While all these marks have a PID, unless one of those positional components is ADJUST NGS does not publish a datasheet for that mark.

The PID for station CMSM-01 is BBCZ31. It's published by NGS as part of the relatively new database they created that is often called OPUS-DB.

I hope some of you may find some time to attend this first ever event from the Maryland Society of Surveyors. MSS Geocaching Event

Mike - GP0237 is already done. I've submitted GP0239. Thanks for bringing this to my attention.

2oldfarts - Be assured that your efforts to provided updated hand-held positions for bench marks with very poor scaled values is not in vain. While I am retired from NGS I do have connections that allow me to update the NGS database that are not available to the general public. Whenever someone submits an HH position to update a scaled value before it goes into the NGS database they run a checking program and anything that shows up as being different by more than 10 seconds of latitude and/or longitude gets flagged for checking. Whenever I harvest positions from this site to update I automatically check to see if they meet that standard. In the case of those such as yours I check your updated position with the description to see that they match. If they do, which they certainly do in your case, then I sent them to a contact at NGS who knows that I perform these checks so they get updated automatically.