Changes in OPUS products when the new NSRS is adopted: what does this mean to users?

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On July 23, 2025, the National Geodetic Survey (NGS) sent a news notice announcing the rollout plan for remaining NSRS modernization products, including OPUS Products Changes, and on June 11, 2025, they sent a news notice to users stating that NGS’s Multi-Year CORS Solution 3 (MYCS3) was released. This newsletter will highlight these two News notices and what they mean to users of the United States National Spatial Reference System (NSRS).

A colleague recently reminded me that the new NSRS is more than just a technical update — it presents an ideal opportunity to review existing processes and workflows, address current products and process considerations, and strategically plan for future requirements. It is well known that the new NSRS will significantly improve geospatial data accuracy. Improved accuracy and reliability of geospatial data empower management to make more informed decisions and optimize resource allocation. NSRS users should proactively assess their geospatial data dependencies and evaluate how adoption of the new datum will affect workflows, datasets and operational decision‑making. I will provide you with more information at a later date.

NGS NEWS

Rollout Plan for Remaining NSRS Modernization products, including OPUS Products Changes

On June 17, 2025, NGS released the first preliminary products of the modernized National Spatial Reference System (NSRS) for beta testing and feedback. In the coming months, additional products listed below will be made available. As each product is released, it will undergo at least six months of testing preceding the final adoption and implementation of the modernized NSRS.

The descriptions below supersede previous updates or information shared in NSRS Modernization blueprint documents, plans, or presentations. These products and their status will be described on the Track Our Progress webpage.

1. The Data Delivery System (DDS) landing page will provide an updated version of the “NGS Map” and “Looking for Benchmarks” pages. This new landing page will allow you to access modernized informational pages about geodetic stations and geodetic marks.
2. Geodetic station pages will offer an updated version of the current NOAA CORS Network (NCN) station pages. Geodetic mark pages will be updated datasheets, replacing the current ASCII text file version of datasheets. The updated coordinates (reference epoch coordinates) for marks and updated CORS coordinate functions (CCFs) for CORSs in the modernized NSRS will be available through these pages. 
3. The NGS Coordinate Conversion and Transformation Tool (NCAT) will be updated through multiple versions, currently with state plane coordinates, then later adding support for various geopotential calculations including ellipsoid/orthometric height conversion as well as NADCON (geometric) and VERTCON (orthometric) transformations from the current NSRS to the modernized NSRS.
4. OPUS-Static will function similarly to today’s tool, but it will operate with the modernized NSRS, including the support of multi-GNSS data. Additionally, the popular function of “sharing” your solution with others (colloquially called “OPUS-Share”) will be retained, but with appropriate caveats that the shared solution should not be used as geodetic control. These shared solutions will be available through the geodetic mark pages of the DDS.

The following products will not be included in the release of the modernized NSRS. However, plans to replace the services or mitigate gaps are described below.

• OPUS-Projects 5 will not be included in the modernized NSRS. Instead, NGS will focus on both developing an improved software suite for OPUS, known as OPUS 6, and minimizing any gap in service in which the current OPUS-Projects functionality is not available for users to organize, process, adjust, and submit high-accuracy GPS surveys for use by NGS in expanding and improving the NSRS. As noted above, OPUS-Share will remain available as a means to submit data to NGS.
• OPUS-Rapid Static (OPUS-RS) will not be included in the modernized NSRS. Instead, the modernized version of OPUS-Static, noted above, will be capable of processing multi-GNSS static data files that are shorter in duration (i.e., less than 2 hours).

Note: the current OPUS Projects 5 software will be supported until the modernized system is adopted, and a deadline for OPUS-Projects users to submit their surveys for publication will be announced with at least six months’ notice.

To stay informed about these releases, please subscribe to NGS News. If you have questions, please email NGS.Feedback@noaa.gov.

Now, I would like to address the issues associated with July 23, 2025, announcement. This NGS News announced the rollout plan for the remaining NSRS modernization products. I have highlighted several sentences in this announcement that I believe users need to understand to determine the impact on their processes and workflows that are used to generate their products and services.

The news announcement states that NGS released the first preliminary products of the modernized National Spatial Reference System (NSRS) for beta testing and feedback. My July 2025 GPS World Newsletter highlighted these preliminary products. It mentioned that in the coming months, additional products will be made available.  Each product will undergo at least six months of testing preceding the final adoption and implementation of the modernized NSRS. This seems to be a good process, but users need to understand the complete message.

The NGS News announcement provides a list of products that will be available and a list of products that will not be available when the new NSRS is adopted. Users need to understand what products will not be available after NGS officially adopts the new NSRS so they can determine what that means to their workflow process and client requirements.  In my opinion, for the new NSRS to be successfully implemented by users, it is essential that all the necessary software tools are available to enable users to submit projects for review, approval, and publication by NGS.  As many of you know, when I worked for NGS, I was the Project Manager of the North American Vertical Datum of 1988 (NAVD 88). That said, from my experience as the NAVD 88 Project Manager, having the appropriate tools available was important for users to implement NAVD 88.  As a matter of fact, NGS accepted and processed vertical control data in both NGVD 29 and NAVD 88 for a period to assist users in the implementation of the new vertical reference datum.

It is important to note that the NGS News Announcement states that OPUS-Project 5 will not be included in the new NSRS when it is officially adopted. See the below image.

Since OPUS Projects 5 will not be supported after the modernized system is adopted, users will not be able to submit their projects for review, approval, and publication by NGS like they can do today. NGS does indicate that they will be working on OPUS 6 to “minimize any gap in service.” There are a few questions that I believe should be addressed: (1) What does “minimize any gap in service” mean? Is this one month, one year, or several years?  (2) Why must the new NSRS be adopted before users can submit their projects to NGS for official publication? And (3) Why should users use OPUS-Share when NGS itself advises against relying on OPUS-Share results for establishing geodetic control?  If the federal agencies and surveying community allow the new NSRS to be adopted before OPUS 6 is available or OPUS Project 5 is modified for use in the new NSRS, the only way to get an updated coordinate such as NATRF2022 and NAPGD2022 using NGS process will be to use NGS OPUS-Share products. Again, NGS states that OPUS-Share results should not be used as geodetic control.  See NGS’ statement on OPUS Share below.

This is NGS’s statement on OPUS-Share: Additionally, the popular function of “sharing” your solution with others (colloquially called “OPUS-Share”) will be retained, but with appropriate caveats that the shared solution should not be used as geodetic control. These shared solutions will be available through the geodetic mark pages of the DDS.

Using OPUS-Share results that are NOT official NSRS coordinates published by NGS could lead to confusing results and potential lawsuits since NGS does not stand behind the results and recommends NOT using OPUS-Share results for geodetic control. Why would users use OPUS-Share to establish geodetic control when NGS itself advises against relying on OPUS-Share for establishing geodetic control?  OPUS-Share results are not officially submitted to NGS for review, approval, and publication on an NGS Datasheet. I don’t believe this approach will meet the needs of users who require their projects to be reviewed, approved, and published by NGS. What is your opinion? You should let NGS, and others know your thoughts and concerns about NGS’s rollout plan for remaining NSRS modernization products.

Now for the release of NGS’s Multi-Year CORS Solution 3 (MYCS3).

First, why did NGS perform the NGS Multi-Year CORS Solution 3 (MYCS3)?  To maintain consistency with the International Earth Rotation and Reference System Service (IERS) and the International GNSS Service (IGS) reference frames, NGS has implemented the new International Terrestrial Reference Frame 2020 (ITRF2020) and IGS20 realizations in the U.S. NOAA CORS Network (NCN). What this means to NSRS users is that NGS has updated the North American Datum 1983 (NAD 83), epoch 2010.0 coordinates for stations in the NOAA CORS Network (NCN). This update is called the Multi-Year CORS Solution 3 (MYCS3).

In summary, the MYCS3 news notice states the following:

• The coordinate functions for NOAA CORS Network (NCN) stations are now consistent with ITRF2020,
• NGS datasheets will display the new NAD 83 coordinates transformed from ITRF2020 coordinate functions,
• The new NAD 83 coordinates will be referenced to NAD 83 2011 (epoch 2010.0),
• Position and velocity files will display coordinates/velocities in both NAD 83 and ITRF2020, and
• The NGS Online Positioning Users Service (OPUS) will begin processing data with NCN control that is consistent with ITRF2020 at the time of measurement; and the results will still be transformed to NAD 83 2011, epoch 2010.0.

The first question that everyone asks is, what are the changes to the coordinates in my region? And, of course, why was it necessary to do this update now, but that’s a discussion for another day.  I downloaded the data and prepared a few plots and a table to depict the differences between the new and old coordinates.  First, it should be noted that the old NCN coordinates were published in ITRF 2014, epoch 2010.0, and the new NCN coordinates are published in ITRF 2020, epoch 2020.0. So, there will be differences in coordinates because of updates between ITRF2014 and ITRF2020, and because the CORS ITRF 2020 coordinates are published at epoch 2020.0 instead of 2010.0.

The image below provides the new and old CORS coordinates and velocity information for NOAA CORS Monroe (NCMR). These values can be obtained from NGS CORS website.

The difference between ellipsoid heights is straightforward.  In the example, the difference is 144.357 meters minus 144.345 meters or 0.012 m. The image captioned “Change in Ellipsoid Height in NC based on ITRF 2020” provides the differences between MYCS3 and MYCS2 NAD83 2011, epoch 2010.0 published ellipsoid heights for the CORS in North Carolina.  In other words, this is the change in the NAD 83 2011, epoch 2010.0 ellipsoid height at the CORS after updating to ITRF2020, epoch 2020.  I’ve highlighted the NCMR CORS in the box. As you can see from the plot, there are several CORS in North Carolina that their ellipsoid heights have changed significantly; that is, greater than 20 mm and as large as -89 mm.

I don’t know about you, but I can’t determine the change in coordinates by looking at XYZ or Latitude/Longitude values.  For the horizontal change I computed the differences in latitude and longitude and converted the results to millimeters. As indicated in the image above, the changes in the horizontal component are typically small; that is, less than a few mm.  There are, however, a few larger changes such as the one at CORS TN1B (which is in Tennessee) that changed 30 mm.

I suppose for all “practical purposes” the changes are small and shouldn’t impact most survey projects.  Some of the larger changes are probably a good thing because that may mean that the CORS coordinates needed to be updated to account for movement or something else that affected the coordinates. I created a table that provides the minimum, mean, and maximum values in ellipsoid height and horizontal differences.  See the table titled “Differences Between MYCS 3 and MYCS  2 Solutions of NOAA CORS.”  I highlighted the State of North Carolina values.

So, why is it important to understand these differences?  The NGS Online Positioning Users Service (OPUS) has begun processing data with NCN control that is consistent with ITRF2020 at the time of measurement.  This means that if you compare old projects to new projects, you may find some small differences due to the change in CORS NAD 83 2011, epoch 2010.0 coordinates.  As I previously mentioned, these differences are small and should not affect the results of most survey projects. Although, any difference can lead to someone questioning their results.

As another example of the changes, the two plots below in the image captioned, “Change in CORS coordinates in Colorado based on ITRF 2020” provides the differences between MYCS3 and MYCS2 NAD83 2011, epoch 2010.0 published coordinates for the CORS in Colorado.

Another difference that I computed using the results from the MYCS3 solution is an estimate of the changes between the current NSRS, that is NAD 83 2011 (epoch 2010.0) and new NSRS, for example NATRF2022, epoch 2020.0.   This is only an estimate but provides a value that users can attain the magnitude of the changes in their local region. The image below depicts the approximate changes in horizontal and vertical components between the current NSRS (NAD 83 2011, epoch 2010.0) and the future NSRS (NATRF2022, epoch 2020.0) based on the CORS in the NCN. (Note that the units have changed to cm.)

To demonstrate that these changes vary region by region, I prepared plots depicting the changes in the State of Washington and the U.S. Gulf Coast region. As indicated in the plots, the differences between the current NSRS and the new modernized NSRS will vary from state to state and are significantly different than the current NSRS coordinates. 

This newsletter underscored upcoming OPUS product changes that NGS will implement following adoption of the modernized NSRS, along with updates to CORS station coordinates resulting from the Multi‑Year CORS Solution 3 (MYCS3). It clarified what these changes mean for users of the U.S. NSRS. I also flagged several topics in the NGS News bulletins that warrant further attention, as they are critical for understanding how the modernized NSRS will impact geospatial products and services.  The new NSRS offers a strategic opportunity for users to comprehensively review existing processes and workflows, reassess current products, and proactively plan for future requirements. By auditing geospatial data dependencies now, NSRS users can evaluate how transitioning to the new datum will impact workflows, datasets, and operational decision-making.

Will you be ready to implement the new NSRS after NGS officially adopts it?  Will you have the appropriate tools available to implement the new NSRS? These are questions that everyone that uses the NSRS should be addressing now.