The federal government shutdown as of Oct.1 is affecting many surveyors who rely on GPS/GNSS, but there are non-federal resources you can use in the meantime. Below are lists of resources as well as explanations of the government’s role in providing data and access to data.
This information has been provided by PSM geodesy editor Dave Doyle; James Shaw, PLS, president of Maryland Society of Surveyors; and additional, helpful leaders in surveying.
Alternate Sources of Observation Files for Post-processing
During the shutdown, the National Geodetic Survey (NGS) website and all affiliated services are discontinued. But there are options available.
Real-time networks (RTN)—private, public, state, local, and cooperative—are not affected by the shutdown. RTN that provide static files for download are a good source for observation files for post-processing while the NGS services are unavailable. Most of the CORS in the NGS National CORS originate from these RTN (see notes from Dave Doyle below). RTN such as Leica SmartNet, Keystone Precision’s KeyNETGPS, Caron Net RTK, the WSRN, and dozens of other RTN are unaffected by the NGS disruption and will continue to provide corrected coordinates on their respective supported systems.
Alternate Sources for NGS Datasheets
Numerous commercial and open-source online sites, such as Google Earth plug-ins like Benchmark Hunter, link to stored copies of datasheets. There are even smartphone apps like Find a Control that can use the GPS on your phone to display monuments near you; once you choose the one you want, it will give you the NGS data sheet. Note that some online resources and apps point to stored copies of NGS datasheets. When NGS services are available, the NGS generates new datasheets incorporating live updates to their databases—copies stored by third parties may be out of date.
Those seeking horizontal or vertical benchmarks will have a more difficult time. However, you can use geocaching tools as a substitute for the NGS database, with limitations. This database is roughly 10 years old, so it will not provide data on new datums or for newly installed monuments, but can be used to assist in continued GNSS/GPS operations.
Alternate Sources for Online Positioning Services
During the shutdown, the NGS Online Positioning Users Service (OPUS) is not available. There are other online positioning services. Check with your local RTN as some have set up online positioning services that work like OPUS but do not necessarily utilize stations included in the national CORS; instead they use data from the local RTN (though nearly all RTN are constrained to the NGS reference framework).
PPP (Precise Point Positioning) is an alternate way to post-process. There is a good summary of the many PPP services available in a recent article from GPS World. Most PPP services, like those offered by the IGS and NASA, use sparse worldwide tracking networks to produce clock and orbit files used in the processing (it is not like the standard baseline processing you are familiar with). These worldwide PPP services typically require much longer observations times (as much as three or four times longer) to yield precisions akin to those from OPUS. Note that PPP services mostly report results in a different reference framework and epoch than OPUS does. There are also some commercial PPP online services available like Centerpoint RTX. Real-time PPP services are also available commercially and from IGS, but these will not (at this time) yield the same precisions as RTK/RTN, and convergence times are much longer.
Details on the NGS
(Questions by John Palatiello and Curt Sumner, answers by Dave Doyle)
Q: Are CORS base stations run by the NGS?
A: No. The national network that NGS provides access to has approximately 2,000 CORS, of which NGS owns maybe around 40. All the rest are owned and operated by a wide variety of partner organizations, including other parts of NOAA and other federal agencies (FAA, USCG, BLM, NPS etc.), academic institutions, state DoTs, local government, and private companies. NGS collects all their data together and ensures they are all in the same coordinate system and maintain a high degree of positional integrity.
Q: Are the base stations collecting data now or have they been shut down?
A: The only CORS that should be directly effected would be those owned and operated by federal agencies that do not have a direct safety of life issue (e.g. NPS, BLM, USFWS etc.). Both the FAA’s WAAS and USCG DGPS stations would be operational. However, they would only be providing their broadcast correction services. Access to the raw data for cm-level processing is the service NGS provides, and that’s not available. Stations of the other agencies may still be running and collecting data if the power hasn’t been turned off. These sites would be limited by how much data they can store in whatever computer systems they’re attached to.
Q: If the base stations are still collecting data, will the data be available for this shutdown time period once the shutdown is over? Meaning: the surveyors out right now collecting static data will need to reference the base station data at some point, but will it be available?
A: If stations are not turned off, then data should be available up to the limit that their respective systems hold. The problem is we don’t have any information about either of these issues of any of the stations in the network. Stations that are not federally owned and operated should still be providing data; the problem may be trying to get in touch with each operator to find out how they store and/or distribute their data. State and private real time networks should be unaffected, at least in the short term. Networks in areas with more severe tectonic motions (e.g. CA, OR, WA) may start to see problems if their stations are not monitored correctly.
Q: Is there another way to access this data?
A: For federal stations the answer is no. But most stations are not federally operated; the majority—operated by state, local, private—often have a download option from the hosts. Check with the RTN in your local area.
Q: Can we argue this is “essential” and should be reactivated even during a shutdown?
A: That’s a case that NSPS would need to make.
Q: Does the military or any first responders need access, thus making this vital to health, welfare and public safety?
A: As I recall, other than USCG there are only a very small number of other military stations in the NGS CORS network—maybe 3 or 4. They would not be impacted. First responders aren’t concerned with cm-level positioning, and whatever systems they’re using should generally be operated by local government not the feds, so they wouldn’t be affected.